WO2023031643A1

WO2023031643A1 - Withdrawable unit for a functional unit compartment of a low-voltage switchgear or controlgear

Info

Publication number: WO2023031643A1
Application number: PCT/IB2021/057926
Authority: WO
Inventors: Peter Alexeev
Original assignee: Elsteel (Private) Limited
Priority date: 2021-08-31
Filing date: 2021-08-31
Publication date: 2023-03-09
Also published as: AU2021463299A1; EP4396912A1

Abstract

The invention is a withdrawable unit, with improved degree of protection from dust and water, used in low-voltage electrical switchgear and controlgear assembly. The withdrawable unit has two synchronized movable operating handles with guide arms; and push and hold locking devices which lock and unlock the withdrawable unit at the test position in its functional unit compartment. The two movable operating handles with the guide arms are locked by handle stoppers and gravity-loaded handle locks and assist the user in inserting and removing a larger withdrawable unit. The gravity-loaded handle locking mechanisms lock the withdrawable unit externally at the connected position and the isolated lockable position. The withdrawable unit comprises an insertion interlock to prevent accident insertion of the withdrawable unit into a wrong functional unit compartment.

Description

TITLE WITHDRAWABLE UNIT FOR A FUNCTIONAL UNIT COMPARTMENT OF A LOW-VOLTAGE SWITCHGEAR OR CONTROLGEAR

TECHNICAL FIELD

The present invention relates to the field of electrical power distribution centers and motor control centers, particularly with regard to withdrawable units which can be fully removed from low-voltage switchgear and controlgear assembly, without switching off the assembly.

BACKGROUND ART

Low-voltage switchgear and controlgear assemblies are intended to be used for distribution of electric power to consumers. The assemblies are internally separated into sections, subsections and compartments depending on the requirements of the end user. There can be three types of compartments in a low-voltage switchgear and controlgear assembly, as per the international standards IEC 61439, i.e. functional unit compartments, busbar compartments and cable compartments. The terminals for external conductors are accommodated in cable compartments. The functional units of a low-voltage switchgear and controlgear assembly are accommodated in functional unit compartments. A functional unit is a drawer-like part of a low-voltage switchgear and controlgear assembly comprising the electrical and mechanical elements including switching devices, conductors connecting a functional unit to the main or distribution busbars and to the terminals for external conductors are part of the functional unit. The functional units of a low-voltage switchgear and controlgear assembly can be of four different types i.e., fixed, plug-in, removable and withdrawable. Each of these units differs from the other in respect of the convenience and usability of inserting and removing out a unit from the low-voltage switchgear and controlgear assembly, without completely shutting down the low-voltage switchgear and controlgear assembly. A withdrawable unit is a functional unit intended to be moved from a connected position to an isolated position and to a test position, while remaining in the functional unit compartment of the low-voltage switchgear and controlgear assembly. When a withdrawable unit is inserted into its functional unit compartment, the male plugs installed inside the withdrawable unit, connects with corresponding female plugs installed inside the functional unit compartment. The withdrawable units contain electrical and mechanical devices which are used to connect and disconnect main circuits and auxiliary circuits. Most of the withdrawable units have three positions - connected position, test position and isolated position. At the connected position the withdrawable unit is fully connected with the main circuits as well as auxiliary circuits. At the test position the main circuit is open, but not necessarily isolated and the auxiliary circuits are connected to allow carrying out test operations, while the withdrawable unit is still inside the functional unit compartment. At the isolated position both the main circuits and the auxiliary circuits are open, while the withdrawable unit still remains in the functional unit compartment.

The low-voltage switchgear and controlgear assembly manufacturers produce withdrawable units with varying features such as locking mechanisms, position indicators, etc... One important concern in today’s low-voltage switchgear and controlgear assembly industry is manufacturing easy-to-operate, space saving low-voltage switchgear and controlgear assemblies. Therefore, manufacturing of a user-friendly easy-to-operate withdrawable unit, without compromising any of its mandatory basic features and safety requirements in compliance with international standards, has become one of the major goals among the manufacturers. In the attempt of designing easy-to-operate larger sizes of withdrawable units, the manufacturers have devised different technologies in mechanical operations related to inserting and removing of withdrawable units as well as in locking and unlocking mechanisms at connected, test and isolated positions.

The present invention is a withdrawable unit equipped with easy-to-operate movable handles locking mechanisms in compliance with international standards. The withdrawable unit disclosed in the present invention uses a push and hold locking device compatible with larger withdrawable units, which locks the withdrawable unit at the test position and a gravity- loaded handle locking mechanism at the connected position and isolated lockable position. The push and hold locking devices are operated by two push buttons on the front surface of the withdrawable unit whereas the gravity-loaded handle locking mechanism locks the withdrawable unit at the connected position as well as at the isolated lockable position by a mechanical operation and is unlocked manually. The two movable operating handles available at the front surface of the withdrawable unit support insertion and removal of the withdrawable unit by the force exerted on its four guide arms. Apart from that the invention uses a final unit release mechanism to enhance the safety of the operators.

The prior art closest to the invention is disclosed in PCT/IB2021/053978-Plug & Power Withdrawable Unit Design #1 of the same inventor and of the same applicant of the present invention. This closest prior art discloses a push and hold locking mechanism operated by a push button, which is devised in smaller withdrawable units. The push and hold locking mechanism in this prior art locks and unlocks the withdrawable unit at the test position and the connected position by means of a movable plate connected with the push button. It also consists of another two locking mechanisms - isolate lockable mechanism and unit release locking mechanism. Although this prior art uses a push button to operate the locking mechanism, the technology used therein is different from the technology used in the present invention in respect of the push and hold locking mechanism and the movable handle mechanism.

The second prior art closer the invention is disclosed in EP2625757-Locking apparatus for withdrawable units for electrical switchgear cabinets-where a different type of locking mechanism operated by a push button is described. Although this invention uses a push button to operate the locking mechanism, the technology used therein is different from the technology used in the invention. The locking mechanism in this prior art uses a locking apparatus of which the locking element is displaced by pressing the push button at different locking positions.

The third prior art closer to the invention is disclosed in Patent No. KR101178740B1- A module type motor control center having a drawing position indicating button type device for drawing the unit thereof - where its lock control mechanism locks the unit using rails installed to prevent relative movement or to release the lock. This prior art has a position control mechanism to indicate the position of the unit visually.

The fourth prior art closer to the invention is disclosed in Patent No. WO/2002/087037- Low voltage switchgear comprising a locking device for an appliance module - where a different locking mechanism is used to lock the unit at different positions. The locking mechanism comprises a locking bar arranged in a housing of the unit, positioning cranks arranged on lateral edges of the bottom of the unit and a lifting gear. TECHNICAL PROBLEM

When it comes to withdrawable units used in a low-voltage switchgear and controlgear assemblies, the size of the withdrawable unit has become one of the important factors in the industry. The low-voltage switchgear and controlgear assembly manufacturers are engaged in continuous research and development work to design operating mechanisms such as locking mechanisms and handling mechanisms which are capable of handling larger withdrawable units in a user-friendly manner. The end users look for easy-to-operate methods when the withdrawable unit becomes larger as the larger withdrawable units are heavy.

Increasing the size of a withdrawable unit is technically a challenging task in respect of maintaining ingress protection ratings (IP Code) as it has to be achieved in compliance with IEC 61439 standards. On one hand, such larger withdrawable units should not compromise the safety requirements expected to be afforded by the overall low-voltage switchgear and controlgear assembly for its operators. The safety of the personnel working around the low- voltage switchgear and controlgear assemblies are one of the most demanding requirements in the industry.

On the other hand, the mechanical operations of the withdrawable unit such as locking mechanisms needs to be isolated from the main objective of the withdrawable unit, i.e. connection and disconnection of internal circuits with incoming and outgoing circuits without shutting down the whole assembly.

DISCLOSURE OF THE INVENTION

The invention is a comparatively larger withdrawable unit, having a drawer like structure, used in low-voltage electrical switchgear and controlgear assembly. The withdrawable unit has two synchronized movable operating handles with guide arms, and push and hold locking devices which lock the withdrawable unit at the test position in its functional unit compartment and unlocks the withdrawable unit with the press of the push buttons. The two movable operating handles with the guide arms assist the user in inserting and removing a larger withdrawable unit. It is also equipped with a gravity-loaded handle locking mechanism to lock the withdrawable unit at the connected position and the isolated lockable position. The withdrawable unit comprises an insertion interlock to prevent accident insertion of the withdrawable unit into a wrong functional unit compartment. The withdrawable unit has provision for position sensor device in order receive an indication of the position of the withdrawable unit.

ADVANTAGEOUS EFFECTS

In addition to the press and hold locking mechanism, the withdrawable unit consists of movable handle mechanism which is used to assist the user with backward force by its subarms and the guide rollers. The movable handle mechanism provides an easy operation - insertion and removal - for larger withdrawable units. The withdrawable unit can be equipped with a position sensor device to identify at which position the withdrawable unit is, when it is inserted or removed. The withdrawable unit has a special bracket to fix a position sensor device. The insertion interlock protects electrical components installed at the rear side of the withdrawable unit, from accidental insertion of withdrawable unit into a wrong functional unit compartment. The withdrawable unit has been improved in terms of its degree of protection (IP Code) when it is fully connected position.

BRIEF DESCRIPTION OF DRAWINGS

Drawings do not appear in their correct scale. Some components of the invention are illustrated comparatively larger or smaller than their actual appearance. Some components of the invention are not shown in some figures in order to show the components behind.

Fig. 1 is an illustration of the invention, i.e. withdrawable unit and rails.

Fig. 2 is an illustration of the external appearance of the withdrawable unit.

Fig.s 2A and 2B are further illustrations of the external appearance of the withdrawable unit as viewed from the left side of the withdrawable unit, without showing the left movable operating handle.

Fig.s 2C and 2D are illustrations of the gravity -loaded handle lock of the withdrawable unit.

Fig. 3is an illustration of the internal appearance of the withdrawable unit as it is viewed from the left side of the withdrawable unit.

Fig. 3A is an illustration of the push and hold locking device and the operating handle mechanism.

Fig.4 is an illustration of the top part of the push and hold locking device as it is viewed from the left side of the withdrawable unit.

Fig. 4A is the illustration of Fig. 4 as it is viewed from the right side of the withdrawable unit.

Fig. 4B is an illustration of the bottom part of the push and hold locking device as it is viewed from the left side of the withdrawable unit.

Fig. 4C is the illustration of Fig. 4B as it is viewed from the right side of the withdrawable unit.

Fig.s 5 and 5 A are illustrations of the operation of trigger plate and top lifting release plate and bottom lifting release plate.

Fig.s 6 and 6A are illustrations of the release pin of the push and hold locking device.

Fig.s 7, 7A and 7B are illustrations of movable operating handle.

Fig.s8 and 8 A are illustrations of the handle stopper. Fig.s8B, 8C, 8Dand 8E are illustrations of arm synchronizing mechanism.

Fig.s 9, 9A and 9B are illustrations of the upper rails and lower rails.

Fig. 10 and 10A is an illustration of the gravity-loaded handle lock.

Fig. 11 is an illustration of the default state of the withdrawable unit when it is completely removed from the functional unit compartment.

Fig. 12 is an illustration of the withdrawable unit at the test position.

Fig. 13 is an illustration of the withdrawable unit at the connected position.

Fig.s 14 and 14A are illustrations of the withdrawable unit at the isolated lockable (service position).

Fig.s 15 and 15A are illustrations of the unit release mechanism of the withdrawable unit.

Fig.s 16 and 16A are illustrations of the operation of the control plug holder and the control plug stopper.

Fig.s 17, 17A, 17B, 17C and 17D are illustrations of the insertion interlock mechanism.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

The invention is a comparatively larger withdrawable unit used in low-voltage switchgear and controlgear assemblies, inside which electrical devices are installed to distribute electrical energy and protect equipment and users from electric shock. The withdrawable unit is accommodated in a functional unit compartment in low-voltage switchgear and controlgear assembly. The plugging devices are installed inside the withdrawable unit and in the functional unit compartment to make necessary withdrawable connections and disconnections. When the withdrawable unit is inserted into its functional unit compartment in the low- voltage switchgear and controlgear assembly, the male plugging devices mechanically connect, at different positions, with their corresponding female plugging devices allowing the power and control connections coming from internal switching devices installed in the withdrawable unit, to be connected with external cables connected with the outgoing circuit. When the withdrawable unit is removed from its compartment in the low-voltage switchgear and controlgear assembly, the incoming connections and the male plugging devices mechanically disconnect with their corresponding female plugging devices and the power connections are disconnected from external cables. The withdrawable unit has locking positions namely test, connected, isolated lockable and unit release, at different locations on its way in and out when it is inserted into and removed from the functional unit compartment. The invention is equipped with two ‘push and hold’ locking mechanisms to lock and unlock the withdrawable unit at the test position, two gravity-loaded handle locking mechanisms to lock the withdrawable unit at the connected position and the isolated lockable position with a further manual locking mechanism to lock the withdrawable unit at the isolated lockable position which is also known as service position. The withdrawable unit is also equipped with two movable operating handles, each of which operates in combination with the respective push and hold locking devices.

Fig. 1 shows an exemplary embodiment of the invention which is a comparatively larger withdrawable unit (1), having a drawer-like structure and a set of rails (80 and 90) made from sheet metal. For the ease of description, the four sides of the withdrawable unit (1) are referenced as front side (2), left side or left sidewall (3), right side or right sidewall (4), rear side or rear sidewall (5), bottom side or bottom sidewall (6) and the top side (7) of the withdrawable unit (1); the direction of movements, i.e. forward and backward referred in the below description, are referenced in relative to the functional unit compartment. Forward movement means moving of the withdrawable unit or a component of it towards the front side of the functional unit compartment. Backward movement means moving of the withdrawable unit or a component of it towards the rear side of the functional unit compartment.

As further shown in Fig. 2, the withdrawable unit (1) is externally comprised with two movable operating handles (10), two handle seal gaskets (11), two push buttons (12), two gravity-loaded handle locks (16) and a front door (13) in its front side (2). The withdrawable unit (1) is comprised with four lock plates (21 and 22) located on the top (7) and the bottom (6) of the withdrawable unit (1). Each of the left side (3) or right side (4) of the withdrawable unit (1) is comprised with a release pin (23), two guide rollers (32) and cutouts (33), an isolate lockable position indicator (71) and bottom wheels (50); and a unit release mechanism (60), position sensor brackets (100) and insertion interlock (110) are on the left side (3) of the withdrawable unit (1). The isolate lockable position indicator (71) can be a sticker or permanent marking on the left or right sidewalls. The position sensor brackets (100) and insertion interlock (110) can be installed to the left sidewall (3) or right sidewall (4) of the withdrawable unit (1) depending on the requirement.

As shown in Fig.s 2A and 2B, a gasket (14) is affixed to the back of the door holding plate

(15) of the withdrawable unit (1). The handle seal gasket (11) shown in Fig. 2 is fixed to the front end of each movable operating handle (10). As shown in Fig.s2C and 2D, there is an adhesive gasket (17) affixed to the front of the door holding plate (15), around the handle slot (18) through which each movable operating handle (10) comes out. The gasket (11) seals the withdrawable unit (1) and the functional unit compartment, when the withdrawable unit (1) is fully inserted into the functional unit compartment and locked by gravity-loaded handle locks

(16). The two gaskets (14 and 17) seal the movable operating handle (10) and the handle slot

(17), when the withdrawable unit (1) is fully inserted into the functional unit compartment and locked by the gravity-loaded handle locks (16). The entrance of water and dust into the withdrawable unit (1) is avoided, when the withdrawable unit (1) is fully inserted into the functional unit compartment and locked. Thus, the degree of protection (IP code) of the withdrawable unit (1) is improved. The two gravity-loaded handle locks (16) used to lock the withdrawable unit (1) at the connected position and at the isolate lockable position, are located on the on the rear side of each movable operating handle (10) of the withdrawable unit (1). As shown in Fig. 3, the locking and unlocking of the withdrawable unit (1) at the test position is achieved by means of two devices (20) fixed internally to the left sidewall (3) and top wall, and the right sidewall (4) and the top wall of the withdrawable unit (1). The unit release mechanism (60) is fixed internally on to the bottom (6) of the withdrawable unit (1). The movable operating handles (10) are movable forward and backward relative to the withdrawable unit (1). The two movable operating handle mechanisms (30) are fixed to the left sidewall (3) and the right sidewall (4) of the withdrawable unit (1). The bottom wheels (50) fixed at the bottom left and the bottom right edges of the withdrawable unit facilitates smooth movement of the withdrawable unit (1) on the rails (90).

As shown in Fig. 3A, each push and hold locking device (20) is comprised with the push button (12), two lock plates (21 and 22), release pin (23) and a movable plate (24) with a trigger plate (25), top lifting release plate (26) and bottom lifting release plate (27).

As further shown in Fig. 3A, the push button (12) is connected to the movable plate (24). The push button (12) is spring-loaded by the spring (12a). As shown in Fig.s 3A and 4, the movable plate (24) is internally fixed to the left sidewall (3) of the withdrawable unit (1) by using press standoffs, plastic washers and screws allowing the movable plate (24) to be moved freely forward and backward through guide slots (24a). The movable plate (24) has a key-hole type slot (24b) closer to its one end. The keyhole-type slot (24b) has two sections, i.e. Section A (24c) which is circular and Section B (24d) which is an ob-round. The front end of the movable plate (24) is bent at right angle and connected to the trigger plate (25) which is used to operate the lock plates (21 and 22) by means of the top lifting release plate (26) and the bottom lifting release plate (27).

As shown in Fig. 4 and 4B, each lock plate (21 or 22) is composed of a head (21a or 22a) of which the top edge is tapered and horizontally straight, vertically straight side edges and a rod (21b or 22b).

As shown in Fig.s 4 and 4A, the rod (21b) of the lock plate (21) on the top of the withdrawable unit (1) is inserted through a spring (21c); a bracket (21d) which is fixed to the inside left sidewall (3) of the withdrawable unit (1) and a guide bush (21e). The guide bush (21e) is riveted to the bracket (21d). The spring (21c) is held between the bracket (21d) and the head (21a). The lock plate (21) is retained in the guide bush (21e) by a nut (21f) in a slightly spring-loaded manner and to freely move up and down inside the guide bush (21e). Thus, the arrangement of the spring (21c), the bracket (2 Id) and the guide bush (21e) allow the lock plate (21) to be pressed or depressed. Since the top edge of the head (21a) of the lock plate (21) is tapered, it gets easily pressed in only one direction, i.e. only when the withdrawable unit (1) is inserted into the functional unit compartment. The rod (21b) of the lock plate (21) goes through the top lifting release plate (26) and held by the nut (211). Thus, by default, the top lifting release plate (26) is pulled up by the spring (21c). The top lifting release plate (26) and the spring-loaded lock plate (21) are coupled together and held by the nut (211) in a manner which the pressing of the spring-loaded lock plate (21) does not make any downward movement of the top lifting release plate (26).

As shown in Fig s 4B and 4C, the rod (22b) of the lock plate (22) on the bottom of the withdrawable unit (1) is inserted through a spring (22c); a bracket (22d) which is fixed to the inside left sidewall (3) of the withdrawable unit (1) and a guide bush (22e). The guide bush (22e) is riveted to the bracket (22d). The spring (22c) is held between the bracket (22d) and the head (22a). The lock plate (22) is fixed slightly spring-loaded using a nut (22f) to freely move up and down inside the guide bush (22e). Thus, the arrangement of the spring (22c), the bracket (22d) and the guide bush (22e) allow the lock plate (22) to be pressed or depressed. Since the top edge of the head (22a) of the lock plate (22) is tapered, it gets easily pressed in only when the withdrawable unit (1) is inserted into the functional unit compartment. The rod (22b) of the lock plate (22) goes through the bottom lifting release plate (27) and held by the nut (22f). The bottom lifting release plate (27) and the spring-loaded lock plate (22) are coupled together and held by the nut (22f) in a manner which the pressing of the spring- loaded lock plate (22) does not make any upward movement of the bottom lifting release plate (26). By default, the bottom lifting release plate (27) is gravity loaded and is pulled down by the spring (22c), and rests on the top edge (25a) of the trigger plate (25).

As shown in Fig. 4A, the top lifting release plate (26) is welded to a bracket (26a) which is fixed to the left sidewall (3) of the withdrawable unit by screws inserted through slots (26b). Thus, the top lifting release plate (26) is movable up and down.

As shown in Fig. 3A and 4B, the bottom lifting release plate (27) is fixed to the left sidewall (3) of the withdrawable unit by screws inserted through slots (27a). Thus, the bottom lifting release plate (27) is movable up and down. As shown in Fig.s 5 and 5A, the top edge (25a) and the bottom edge (25b) of the trigger plate (25) are tapered and horizontally straight. The top lifting release plate (26) and the bottom lifting release plate (27) have squares lots (26c and 27a) respectively. The top lifting release plate (26) and the bottom lifting release plate (27) are coupled together by a press standoff (28a), a washer (28b) and a screw (28c). The press standoff (28a) is inserted through a hole (27b) on the bottom lifting release plate (27) and the screw (28c) is inserted through a slot (26e) on the top lifting release plate (26) in a manner which both lifting release plates (26 and 27) can be moved up and down freely in the slot (26e). By default, the top edge (27c) of the square slot (27a) on the bottom lifting release plate (27) rests on the tapered section of the top edge (25a) of the trigger plate (25). By default, the bottom edge (26d) of the square slot (26c) on the top lifting release plate (26) is contacted with the tapered section of the bottom edge (25b) of the trigger plate (25).

As shown in Fig.s 6 and 6A, the release pin (23) is internally fixed to a bracket (23a) which is fixed to the inside top wall of the withdrawable unit (1). The release pin (23) has a step (23b). The release pin (23) is inserted through a spring (23c); the bracket (23a) and a guide bush (23d). The guide bush (23d) is riveted to the bracket (23a). The spring (23c) is held between the bracket (23a) and the step (23b). The release pin (23) is fixed slightly spring-loaded using a nut (23 e) to be able to freely move inside the guide bush (23d). Thus, the arrangement of the spring (23c), the bracket (23a) and the guide bush (23d) allow the release pin (23) to be pressed or depressed. The head (23f) of the release pin (23) passes through the keyhole-type slot (24b) on the movable plate (24). By default, the front edge of the step (23b) of the release pin (23) hits and stops at the inside edge of the Section B (24d) of the keyhole-type slot (24b). Thus, the release pin (23) is further spring-loaded. The width of the Section B (24d) of the keyhole-type slot (24b) is slightly greater than the diameter of the head (23f) of the release pin (23) enabling it to come out through the Section B (24d) of the keyhole-type slot (24b). The diameter of the step (23b) is slightly greater than the diameter of the head (23f) of the release pin (23) enabling it to rest at the inside edge of the Section B (24d) of the key hole type slot (24). The diameter of the step (23b) of the release pin (23) is slightly lower than the diameter of the Section A (24c) of the keyhole-type slot (24b) enabling the release pin (23) to come out through Section A (24c), allowing the spring (23c) to extend its original state. The pressing or/and depressing of the release pin (23) or/and the push button (12) are operated in association with the forward and backward movement of the movable plate (24) as described in the following paragraph 2 and 3 on page 13.

[Paragraph 2 of page 13]

When the movable plate (24) moves backward in relative to the release pin (24), the Section A (24c) of the keyhole-type slot (24b) moves to the location of the release pin (23). As a result, the step (23b) of the release pin (23) comes out through the Section A (24c) of the keyhole-type slot (24b) as it (24) is spring-loaded by the spring (23c). Thereafter, the movable plate (24) is held by the step (23b) of the release pin (23) without allowing any further movement of the movable plate (24). As a result, the push button (12) is kept pressed and the spring (12a) is kept loaded. Thus, the release pin (23) is depressed when the movable plate (24) moves backward in relative to the release pin (23). Simultaneously, the movable plate (24) moves backward in relative to the release pin (23), the trigger plate (25) connected with the movable plate (24) is also moved backward. As a result, the top lifting release plate (26) is pulled downward by the bottom edge (25b) of the moving trigger plate (25) where the spring (21c) is further loaded and the lock plate (21) is pressed; the bottom lifting release plate (27) is lifted upwards by the top edge (25a) of the moving trigger plate (25) where the spring (22c) is further loaded and the lock plate (22) is pressed.

[Paragraph 3 of page 13]

When the release pin (23) is pressed inwards by any means, the step (23b) is moved inward and allows the movable plate (24) to be moved forward by the loaded spring (12a) and brings the push button (12) from its pressed state to depressed state. The forward movement of the movable plate (24) brings the Section B (24d) of the keyhole-type slot (24b) to the location of the release pin (23). As result, the step (23b) hits and rests at the inside edge of the Section B (24d) of the keyhole-type slot (24b). Thus, the release pin (23) becomes pressed. Simultaneously, the forward movement of the movable plate (24) also moves the trigger plate (25) forward. As result, the top lifting release plate (26) is lifted upward by the loaded spring (21c) where the spring (21c) is partly unloaded by the loaded spring (21c) where the spring (21c) is partly unloaded, i.e. the top lifting release plate (26) moves upwards; and the bottom lifting release plate(27) is pulled downward by the loaded spring (22c) where the spring (22c) is partly unloaded, i.e. the bottom lifting release plate (27) moves downwards; whereby the top and bottom lock plates (21 and 22) are depressed outside the withdrawable unit (1) and touch the longitudinal surfaces (80a) of the rails (80 and 90).

By default, the release pin (23) is in the pressed state; the lock plates (21 and 22) and the push button are in the depressed state. When the push button (12) is pressed the movable plate (24) moves backward and the operation described in Paragraph 2 of page 13 occurs. As a result, the release pin (23) becomes depressed and the lock plates (21 and 22) become pressed. When the release pin (24) is pressed inwards by any means the operation described in Paragraph 3 of page 13 occurs. As a result, the push button (12) becomes depressed and the lock plates (21 and 22) also become depressed.

As shown in Fig. 7 and 7A, the movable operating handle (10) is made up as a combination of two sections of steel plates, i.e. first section and second section (10a and 10b), connected together by rivets (10c). The movable operating handle (10) is fixed to the left sidewall (3) of the withdrawable unit (1) by through-hole press standoffs, steel spacers, machined pins inserted through the three guide slots (lOd) in the second section (10b) of the movable operating handle (10); and two machined pins inserted through the two guide slots (lOd) in the first section (10a) of the movable operating handle (10). Thus, the movable operating handle (10) is fixed to the withdrawable unit (1) in a movable manner towards backward and forward in relative to the withdrawable unit (1) between the two ends of the guide slots (lOd).

As shown in Fig. 7, 7A and 7B, a guide arm (40) is a combination of two sub-arms, i.e. first sub-arm and second sub-arm (40a and 40b). One end of the first sub-arm (40a) is fixed to the top corner of the second section (10b) of the movable operating handle (10) by a machined rivet pin, washer and circlip in a rotatable manner about the fixing point (40f). The other end of the first sub-arm (40a) and one end of the second sub-arm (40b) are connected to each other as a freely rotatable riveted joint about the fixing point (40c), by a spacer, washer and a machined rivet pin (40d). The other end of the second sub-arm (40b) is formed as a rectangular-shaped control plug stopper (41) with a tab (42) and the guide roller (32). The guide roller (32) is riveted on to the control plug stopper (41) at the end of the second subarm (40b) in a manner which the guide rollers (32) come out from cutouts (33), with reference to Fig. 2, on the left sidewall (3) of the withdrawable unit (1). The second sub-arm (40b) is fixed to the left sidewall (3) of the withdrawable unit (1) by machined pin, washer and a circlip as a freely rotatable manner about the fixing point (40e). Similarly, another guide arm (40) is fixed to the bottom corner of the second section (10b) of the same movable operating handle (10). Thus, both operating handles (10) are fixed with two such guide arms (40).

When the movable operating handle (10) is moved backward, i.e. pushed in, the guide arms (40) are contracted to their maximum allowed length by folding the sub-arms (40a and 40b); thereby, the top and the bottom control plug stoppers (41), together with the tab (42) and the guide roller (32), move outwards on a circular path, i.e. the tab (42) and the guide roller (32) on each of the two control plug stoppers (41) of the top and the bottom sub-arms (40b) of the same movable operating handle (10), rotate away from each other. When the movable operating handle (10) is moved forward, i.e. drawn out, the guide arms (40) are extended to their maximum allowed length by unfolding the sub-arms (40a and 40b); thereby, the top and the bottom control plug stoppers (41), together with the tab (42) and the guide roller (32), move inward on a circular path, i.e. the tab (42) and the guide roller (32) on each of the two control plug stoppers (41) of the top and the bottom sub-arms (40b) of the same movable operating handle (10), rotate towards each other.

As shown in Fig. 8 and 8A, two handle stoppers (34 and 35) are used to lock the two movable operating handles (10) when they (10) are fully drawn out, i.e. moved forward. Each handle stopper (34 or 35) consists of a locking slot (34a or 35a) with a lock hole (34bor 35b) located on the second section (10b) of the movable operating handle (10) and lock pins (34c and 35c) located on the bottom lifting release plate (27).

As shown in Fig. 8A, the locking pin (34c or 35c) is a round pin with a flat side (34d or 35d) welded to the bottom lifting release plate (27), where the flat side (34d or 35d) faces parallel to the front side (2) of the withdrawable (1). As shown in Fig. 8, the lock hole (34b or 35b) on the second section (10b) of the movable operating handle (10), is an ob-round located vertically to the locking slot (34a or 35a), where the vertical length of the ob-round is shorter than the horizontal length of the locking slot (34a or 35a).

[Paragraph 4 of page 15]

When the movable operating handle (10) is moved forward, the locking slots (34a and 35a) slide in relative to the lock pins (34c and 35c). When the lock pins (34c and 35c) reach the lock holes (34b and 35b), lock pins (34c and 35c) fall in to the lock holes (34b and 35b) and get locked as the bottom lifting release plate (27) is pulled down by the spring (21c) and the gravity load of the bottom lifting release plate (27). Thus, the movable operating handle (10) gets locked. The shape of the lock pin (34c or 35c) and the lock hole (34b or 35b) prevent the slipping of the movable operating handle (10) when the movable operating handle (10) is pushed backward. When the push button (12) is pressed, the lock pins (34c and 35c) move upwards from the lock holes (34b and 35b), as the bottom lifting release plate (27) is pulled up by the trigger plate (25) as described above. Thus, the movable operating handle (10) is unlocked and thereafter it can be moved backward until the movable operating handle (10) is locked by the gravity-loaded handle lock (16).

As described in Paragraph 4 of page 15 and Paragraph 3 of page 18, the movable operating handles (10) are two-way lockable by the gravity-loaded handle locks (16) when the movable operating handles (10) are fully pushed into the withdrawable unit (1); and by the handle stoppers (34 and 35) when the movable operating handles (10) are fully drawn out from the withdrawable unit (1).

As shown in Fig. 8B and 8C, the two movable operating handles (10) are mechanically joined to each other in order to synchronize the other handle when one handle is pushed-in or drawn-out. The synchronization is achieved by two synchronizing arms (51 and 52) and a synchronizing rod (53). As shown in Fig. 8D, each synchronizing arm (51 or 52) is a combination of two sub-arms (51a and 51b or 52a and 52b). One end of each sub-arms (51a and 52a) is fixed to the first section (10a) of the two movable operating handles (10) in a rotatable manner about the fixing point (51c and 52c) using a pin inserted through holes (54) on the first section (10a), washer and a circlip. The other end of the sub-arm (51a or 52a) is joined to one end of the sub-arm (51b or 52b) in a rotatable manner about the fixing point (5 Id or 52d) using a rivet pin and a washer. The other end of the sub-arm (51b or 52b) is welded to the synchronizing rod (53). As shown in Fig. 8E, each end of the synchronizing rod (53) is also fixed to an adjustable profile (55) in a rotatable manner about a fixing point (53a) by screw. When either of the synchronizing arms (51 or 52) is folding the synchronizing rod (53) rotates about the fixing point (53a). When either of the synchronizing arms (51 or 52) is unfolding the synchronizing rod (53) rotates about the fixing point (53a) to the opposite direction. Thus, if the operator pushes-in only one movable operating handle (10), the synchronizing arm (51 or 52) unfolds rotating the synchronizing rod (53). As a result, the other synchronizing arm (52 or 51) fixed to the other end of the synchronizing rod (53) also unfolds simultaneously, pushing-in the other movable operating handle (10) fixed to the synchronizing arm (52 or 51). If the operator draws-out only one movable operating handle (10), the synchronizing arm (51 or 52) folds simultaneously, rotating the synchronizing rod (53). As a result, the other synchronizing arm (52 or 51) fixed to the other end of the synchronizing rod (53) also folds, drawing-out the other movable operating handle (10) fixed to the synchronizing arm (52 or 51). Thus, although only one movable operating handle (10) is operated, the other movable operating handle (10) is moved mechanically without the user’s intervention. This synchronization of the two movable operating handles (10) prevents the withdrawable unit (1) being damaged when the user pushes-in or draws-out the withdrawable unit (1) only from one movable operating handle (10).

As further shown in Fig. 8E, the adjustable profile (55) is fixed to the door holding plate (15) using screws (55a) inserted through holes (15a) located on the rear side of the door holding plate (15). The holes (15a) are a series of holes located vertically along the rear side of the door holding plate (15) in equal distance. The holes (54) are a series of holes located vertically on the first section (10a) of each movable operating handle (10), in an equal distance equivalent to the distance between two holes (15a). The holes (54) are used to fix one end of the sub-arms (51a or 52a) to the first section (10a) of the two movable operating handles (10). The two series of holes (15a and 54) on the rear side of the door holding plate (15) and on the first section (10a) of each movable operating handle (10), are used to adjust the position of the two synchronizing arms (51 and 52) and the synchronizing rod (53) whenever the synchronizing rod (53) obstruct installation other equipment inside the withdrawable unit (1).

As shown in Fig. 9, the rails, i.e. two upper rails (80) and two lower rails (90) are used to guide and accommodate the withdrawable unit (1) in its functional unit compartment of a controlgear and switchgear assembly. The front side of each rail (80 and 90) is identified by a debossed arrow (81 and 91).

[Paragraph 3 of page 17]

As shown in Fig. 9A, the two upper rails (80) are metal plates having two surfaces (80a and 80b) bended at right angle. There is a rectangular-shaped lock hole (88) on the longitudinal surface (80a) of the upper rails (80). The longitudinal edge of the surface (80b) is further bended at right angle to make the longitudinal edge (80c) with a tapered end (82). At the front end of the upper rail (80), the edge of the longitudinal surface (80b) is bent at the right angle to make a safety stopper (80d). Two guide blocks (83 and 84) are fixed by screws to the surface (80b). The height of the guide block (83) is smaller than the height of the guide block (84). The width of the guide block (83) is greater than the width of the guide block (84). A stopper plate (89) is welded to the longitudinal surface (80b) of the upper rails (80), towards the front side of the longitudinal surface (80b), keeping the same distance existing between the two guide blocks (83 and 84) and the guide block (83) and the stopper plate (89). Two spring steel plates (86) are welded to the longitudinal surface (80b) of the upper rails (80).

As further shown in Fig. 9A, a release plate (85) is a metal plate welded on the longitudinal surface (80b) of the upper rails (80). The release plate (85) is formed with a tapered tab (85a), a tapered dip (85b) and a tapered tab (85c). The longitudinal surface (80b) of the upper rails (80) has two spring steel plates (86) welded to the longitudinal surface (80b). The upper rails (80) are fixed to frame members in the functional unit compartment using screws inserted through embossed fixing holes (87) on the longitudinal surface (80b).

As shown in Fig. 9B, the two lower rails (90) are metal plates having two surfaces (90a and 90b) bended at right angle. There is a rectangular-shaped lock hole (88) on the longitudinal surface (90a) of the lower rails (90). The longitudinal edge of the surface (90b) is further bended at right angle to make the longitudinal edge (90c) with a tapered end (93). The lower rails also consist of the guide blocks (83 and 84), the stopper plate (89) and the spring steel plates (86) fixed to the longitudinal surface (90b) in a corresponding manner as described in Paragraph 3 of page 17 for the upper rails (80). A blocking tab (92) is welded to the longitudinal surface (90b). The lower rails (90) are fixed to frame members in the functional unit compartment using screws inserted through embossed fixing holes (94).

[Paragraph 3 of page 18]

As shown in Fig. 10 and 10A, the gravity-loaded handle lock (16) on the rear side of each movable operating handle (10) consists of two handle lock pins (16a) and lock plate (16b) with two bended flaps (16d) and a lifting plate (16c) welded to the lock plate towards the top section from the center. The two handle lock pins (16a) are fixed to the front side of the door holding plate (15) of the withdrawable unit (1). The lock plate (16b) with two bended flaps (16d) is fixed to the movable operating handle (10) in a vertically slidable manner. When the movable operating handle (10) is fully inserted into the withdrawable unit (1), the movable operating handle (10) comes as closest as possible to the door holding plate (15). At this instance the two flaps (16d) of the gravity-loaded handle lock (16) are lifted up by the tapered heads (16e) of the lock pins (16a); and at the highest end of the tapered heads (16e), the two flaps (16d) are dropped down due to the gravity and engaged with the lock pins (16a). Thus, the movable operating handles (10) are locked by the gravity-loaded handle lock (16).

[Paragraph 1 of page 19]

As shown in Fig.11, when the withdrawable unit (1) is completely removed from its functional unit compartment, the push buttons (12) are in the depressed state; the lock plates (21 and 22) are in the depressed state; the release pins (23) are in the pressed state; the movable operating handles (10) are drawn out and in the locked position; and the control plug stoppers (41) together with guide rollers (32) have moved inward towards each other. Thus, the withdrawable unit (1) is in its default state.

As described in Paragraph 1 of page 19 and as shown in Fig. 11 (and with reference to Fig. 9 and 9A), the two movable operating handles (10) are drawn out and get locked, when the withdrawable unit (1) is removed from the functional unit compartment. As shown in Fig. 12, when the withdrawable unit (1) is inserted into the functional unit compartment, the guide rollers (32) hit the guide blocks (84) on the upper and lower rails (80 and 90) and stop the withdrawable unit (1) moving further into the functional unit compartment. At this position, which is the test position, the lock plates (21 and 22) are depressed into the rectangularshaped lock holes (88) on the longitudinal surface (80a) in the upper rails (80) as they are spring-loaded. The release pin (23) reaches the tapered dip (85b) on the release plate (85) while it (23) is still in the pressed state. Thus, at the test position, the withdrawal unit (1) is locked as it (1) cannot be moved backward due to the four guide rollers (32) being blocked by the four guide blocks (84) on the upper rails (80) and lower rails (90); and it (1) cannot be moved forward due to the four lock plates (21 and 22) being depressed into the four lock holes (88) on the upper rails (80) and lower rails (90).

[Paragraph 3 of page 19]

In order to unlock the withdrawal unit (1) at the test position, the two push buttons (12) are pressed. When a push button (12) is pressed, the trigger plate (25) of the movable plate (24) moves backward, moving the top lifting release plates (26) downward; and moving the bottom lifting release plate (27) up; whereby the top and the bottom lock plates (21 and 22) are pressed inside the withdrawable unit (1) so that the lock plates (21 and 22) are no longer blocked in the lock holes (88). As a result of the upward movement of the bottom lifting release plate (26), the lock pins (34c and 35c) are lifted up, unlocking the movable operating handles (10), whereby the movable operating handle (10) becomes movable backwards. Simultaneously, the backward movement of the movable plate (24) carries the keyhole-type slot (23g) backward relative to the release pin (23). As a result, the Section A (24c) of the keyhole-type slot (24b) is brought to the location of the release pin (23). When the Section A (24c) reaches the release pin (23), the release pin (23) gets depressed through the Section A (24c) of the keyhole-type slot (24b) on the movable plate (24), since the release pin (23) is spring loaded. The movable plate (24) is held by the step (23b) of the release pin (23). As a result, the push button (12) becomes spring-loaded and is held in the pressed state. The guide slots (24a) support the movable plate (24) to move forward and backward relative to the withdrawable unit (1). Thus, by pressing the push buttons (12) at the test position, the lock plates (21 and 22) are pressed; the release pins (23) are depressed simultaneously; and the two movable operating handles (10) are unlocked and movable backward. Therefore, the withdrawable unit (1) is unlocked. When the operating handles are moved backward the guide rollers (32) are moved outwards from each other further into the gap between the guide blocks (83 and 84) on the upper and the lower rails (80 and 90) while the withdrawable unit (1) is also moving towards the connected position.

Once the withdrawable unit (1) is unlocked at the test position, the withdrawable unit (1) can be pushed towards the connected position or drawn out until unit release mechanism stops the withdrawable unit (1).

After having pressed the push button (12) and unlocked the withdrawable unit (1) at the test position, when withdrawable unit (1) is pushed in towards the connected position by the movable operating handles (10), the release pin (23) hits and get pressed by the tapered tab (85c). At this position, the lock plates (21 and 22) have passed the lock holes (88). Once the release pins (23) are pressed inward, the operation described in the Paragraph 3 of page 13 occurs and as a result of the downward movement of the bottom lifting release plate (26), the lock pins (34c and 35c) fall on the locking slots (34a and 35a). Thus, the lock plates (21 and 22) become depressed; the release pins (23) become pressed; and the push buttons (12) become depressed as soon the withdrawable unit (1) is pushed in towards the connected position from the test position.

Simultaneously, after having pressed the push button (12) at the test position, when the withdrawable unit (1) is pushed in by the movable operating handle (10), from the test position towards connected position, the unlocked movable operating handle (10) moves backward whereby the lock pins (34c and 35c) slid away from the locking holes (34b and 35b) through locking slots (34a and 35a); and the outwardly moving guide rollers (32) allow the withdrawable unit (1) to move to the connected position by means of the allowance created by folding the sub-arms (40a and 40b) while the guide rollers (32) stay in between the two guide blocks (83 and 84).

With reference to Fig. 13, when the withdrawable unit (1) is at the connected position, the operating handles (10) are fully slid into the withdrawable unit (1) through guide slots (lOd) and the sub-arms (40a and 40b) are folded to the maximum where the guide rollers (32) rest between the stoppers (83 and 84), and the withdrawable unit (1) is fully inserted into its functional unit compartment where the movable operating handles (10) reach the door holding plate (15) and are locked by the gravity-loaded handle locks (16) as described in Paragraph 3 of page 18. At this position, the handle seal gasket (11) and the adhesive gasket (17) on the door holding plate (15) are properly sealed by the gravity-loaded handle lock (16). Thus, the withdrawable unit (1) is protected from the ingress of dust and water from the movable operating handles (10). When the withdrawable unit (1) is at the connected position, the lock plates (21 and 22) in the depressed state; the release pins (23) are in the pressed state; and the operating handles are locked by the gravity-loaded handle locks (16).

In order to unlock the withdrawal unit (1) at the connected position, the two bended flaps (16d) on the lock plate (16b) at the two ends of the gravity-loaded handle lock (16), are disengaged from the lock pins (16a) by manually sliding up the lock plate (16b) from the lifting plate (16c). When the withdrawable unit (1) is drawn out from the movable operating handles (10) from the connected position, the movable operating handles (10) slid forward; the two release pins (23) are in the pressed state; the two push buttons are in the depressed state; the sub-arms (40a and 40b) are unfolded while the guide rollers (32) are hitting and exerting force on the guide blocks (84) on the upper and the lower rails (80 and 90); and the movable operating handles (10) finally get locked by the handle stoppers (34 and 35).When the guide rollers (32) hit and exert force on the guide blocks (84), the reverse force generated on the withdrawable unit (1) pushes the withdrawable unit (1) to be moved forward against the plugging load at the connected position. Thus, the withdrawable unit is unlocked from the connected position and drawn out from the movable operating handles (10) until it (1) gets locked at the test position by the lock plates (21 and 22) depressing into rectangular- shaped lock holes (88).

In order to unlock the withdrawable unit (1) at the test position and further drawn out from the test position by the movable operating handles (10), the two push buttons (12) are pressed and the operation described in Paragraph 3 of page 19 occurs. As a result, the lock plates (21 and 22) become pressed; the release pins (23) become depressed simultaneously; and the operating handles (10) become unlocked. As soon as the withdrawable unit (1) is drawn out from the test position, the depressed release pins (23) hit and pressed by the tapered tab (85a). At this position, the lock plates (21 and 22) have passed the lock holes (88). Once the release pins (23) are pressed inward, the operation described in the Paragraph 3 of page 13 occurs. Then, the lock plates (21 and 22) become depressed; the release pins (23) become pressed; the push buttons become depressed. The withdrawable unit is drawn out from the movable operating handles (10) and it (1) gets stopped finally by the unit release mechanism (60). The movable operating handles (10) get locked by the handle stoppers (34 and 35) when the withdrawable unit (1) is drawn out by the movable operating handles (10). At this position, the withdrawable unit (1) can be pushed in until it gets locked at the test position.

As shown in Fig.s 9A, 9B, 14 and 14A, there is an isolated lockable mechanism (70) which is used to lock the withdrawable unit (1) for maintenance requirements. The withdrawable unit is drawn out from the test position or inserting into the functional unit compartment, until the isolate lockable position indicator (71) on the left and the right sidewalls (3 and 4) of the withdrawable unit (1) reach the functional unit compartment level. This position is called the isolated lockable position. At this position, the two push buttons (12) are pressed to unlock the movable operating handles (10) from handle stoppers (34 and 35) and the movable operating handles (10) are fully pushed in until they (10) reach to the door holding plate (15) and gets locked by the gravity-loaded handle locks (16). As a result, the sub-arms (40a and 40b) are folded and the guide rollers (32) are moved into a gap (72) between the stopper plate (89) and the guide block (83) on the upper and lower rails. In order to assure further safety, the movable operating handles (10) of the withdrawable unit (1) is locked using a padlock inserted through two padlock holes (73) on the left or right sidewall (3) of the withdrawable unit (1). As the padlock hits a pin (74) fixed on the first Section (10a) of the movable operating handle (10) and blocks the movement of the movable operating handle (10). In order to unlock the withdrawable unit (1) at the isolated lockable position, the padlock inserted through the two padlock holes (73), is unlocked and removed; the movable operating handles (10) are unlocked from the gravity-loaded handle locks (16) and the movable operating handles (10) are drawn out until they are locked again by the handle stoppers (34 and 35). Thereafter, the withdrawable unit is pushed in towards the test position or drawn out until stopped by the unit release mechanism (60).

The gravity-loaded handle lock (16) is used to lock the withdrawable unit at two positions, i.e. the connected position and isolated lockable position. When the movable operating handles (10) are locked by the gravity-loaded handle lock (16), the sub-arms (40a and 40b) are folded to their maximum; the guide rollers (32) rest in the gap between the guide blocks (83 and 84) on the upper and the lower rails (80 and 90) at the connected position; the guide rollers (32) rest in the gap between the stopper plate (89) and the guide block (83) on the upper and lower rails (80 and 90) at the isolated lockable position.

When the withdrawable unit (1) is being removed from its functional unit compartment, it finally gets locked by the unit release mechanism (60). As shown in Fig.s 15 and 15A, the unit release mechanism (60) is operated by a locking arm (61) with a locking tab (61a) and an operating point (61b), all of which are cut and bent from a single sheet of metal. The locking arm (61) is spring loaded with a spring (62) and is fixed to the bottom (6) of the withdrawable unit (1) by a pin (63) enabling the locking arm (61) to be freely rotated around the pin (63). There is a slot (64) on the locking arm (61) which is used to limit the movement of the locking arm (61) with the help of pin (65). The two pins (63 and 65) are fixed using circlips. The rear edge of the locking tab (61a) is tapered while the front edge is straight. The left sidewall (3) has a cutout (66) for the locking tab (61a) and a cutout (67) for the operating point (61b) on the bottom of the left sidewall (3) of the withdrawable unit (1). The locking arm (61) is fixed to the withdrawable unit (1) and spring loaded in a manner where the locking tab (61a) and operating point (61b) come out through the cutouts (66 and 67) respectively. When the withdrawable unit (1) is drawn out from the functional unit compartment, locking tab (61a) of the locking arm (61) hits and stops at the blocking tab (92) on the lower rail (90) with reference to Fig. 9B. In order to unlock and fully remove the withdrawable unit (1), the operating point (61b) is pressed inwards by a finger and the withdrawable unit (1) is drawn out. It provides additional safety when fully removing the withdrawable unit (1) from the functional unit compartment. In the absence of such locking mechanism, there is a high risk of falling the withdrawable unit down and injure the operator. When the withdrawable unit (1) is inserted to the functional unit compartment, the tapered edge of the locking tab (61a) hits and is pressed inside by the blocking tab (92) without any additional operation.

As shown in Fig.s 9A and 15B, when the withdrawable unit (1) is completely removed from the functional unit compartment and inserted again, the withdrawable unit (1) gets locked at the test position provided that the push buttons (12) are in default state, i.e. depressed state. When the push buttons (12) are pressed, the lock plates (21 and 22) are in the pressed state; the release pins (23) are in the depressed state; and the movable operating handles (10) are unlocked from the handle stoppers (34 and 35). In case the withdrawable unit (1) is inserted into the functional unit compartment while the push buttons (12) are pressed, the release pins (23) hit the safety stopper (80d) on the upper rails (80) and prevent the withdrawable unit (1) being further inserted into the functional unit compartment. This safety mechanism prevents the withdrawable unit being inserted into the functional unit compartment with a wrong operation. Thus, the safety mechanism protects the withdrawable unit (1) from possible damages when the withdrawable unit (1) is inserted into the functional unit compartment with an unintended wrong push button (12) operation. In such case, the withdrawable unit (1) is drawn out of the functional unit compartment; the movable operating handles are fully drawn out; and the release pins (23) are pressed by a finger to bring the lock plates (21 and 22) and the push buttons (12) to depressed state, i.e. the withdrawable unit is brought to the default state.

As shown in Fig s 16 and 16A, there is a male component of a control plug fixed to a spring- loaded control plug holder (43) with a tab (44), fixed at the rear side (5) of the withdrawable unit (1). In withdrawable units, male and female parts of control plug need to be properly connected at the test position and such connection should be maintained while the withdrawable unit is being moved between the test position and the connected position. The plugging load which exerts forward at the time of making the connection, needs to be stopped to establish a proper connection at the test position. Hence, at the test position the male component of the control plug connects with its corresponding female component of the control plug while the tab (44) on the control plug holder (43) is hitting the tab (42) on the control plug stopper (41) and blocks the forward movement of the spring-loaded control plug holder (43). This arrangement allows the control plug to properly establish the connectivity between it male and female components. After having pressed the push button (12) at the test position, when the withdrawable unit (1) is pushed in by the movable operating handles (10), towards connected position, the unlocked movable operating handles (10) move backward whereby the corresponding control plug stopper (41) rotates outward unblocking the tab (44) on the control plug holder (43), which enables the control plug holder (43) to move further forward in relative to the withdrawable unit (1) to maintain the proper connection. When the withdrawable unit (1) is in the connected position, the spring-loaded control plug holder (43) reaches its maximum towards the front. When the withdrawable unit (1) is unlocked and moved from the connected position to the test position, the spring-loaded control plug holder (43) moves backward and reaches the maximum towards the back, in relative to the withdrawable unit (1); the corresponding control plug stopper (41) with the tab (42) rotates inward as the movable operating handles (10) are moved forward; each tab (44) passes the tab (42) of the control plug stopper (41) allowing the tab (42) to move to the blocking position again at the test position. The above movement of the control plug holder (41) is described in relative to the forward and backward movement of the withdrawable unit (1) from the test position to connected position and vice versa.

As shown in Fig.17, 17A and 17B, the withdrawable unit (1) has an insertion interlock (110) implemented using different arrangements of slotted round pins (111) and square pins (112). The slotted round pins (111) are fixed to a bracket (115) with threaded holes to make a certain arrangement of slotted round pins (111). The slots on the slotted round pins (111) are used to fix the pins (111). The bracket (115) is fixed outside the left sidewall (3) or right sidewall (4) of the withdrawable unit (1) by two screws (117). The sidewall (3 or 4) to which the bracket (115) is fixed, is determined as per the design requirement. As shown in Fig.s 17B and 17C, the square pins (112) are first fixed to a plate (113) having three round holes (119) in a row, by lock nuts (118). A bracket (116) having a square hole and two round holes in each row is used to fix the plate (113) with the square pin (112). Each square pin (112) with the plate (113) is inserted into a square hole on the bracket (116) to make the matching arrangement of square pins (112) and fixed to the bracket (116) by a screw inserted into either of the remaining two round holes (119) on the plate. The square pins (112) need to be fixed closer to each other to increase the number of combinations.

When two square pins (112) with the plates (113) are arranged in line next to each other, screws used to fix the plate (113) to the bracket (116) cannot be fixed in line next to each other due to lack of space. Therefore, the screws are fixed in a zig-zag manner using either of the two holes (119). The bracket (116) is fixed to a frame member of the functional unit compartment by two screws inserted through holes (114) on the bracket (116).

As shown in Fig. 17D, the arrangement of slotted round pins (111) fixed on a withdrawable unit and the arrangement of square pins (112) fixed on the bracket (116) are arranged in a manner which allows one arrangement of slotted round pins (111) to pass through the relevant arrangement of square pins (112), if the correct withdrawable unit (1) is inserted in the correct functional unit compartment. Thus, the insertion interlock (110) prevents inserting of the withdrawable unit into a wrong functional unit compartment before it gets locked at the test position as the insertion interlock (110) is located closer to the rear side of the withdrawable unit (1).

As shown in Fig. 17, position sensor brackets (100) are fixed to the left (3) sidewall of the withdrawable unit (1). The position sensor brackets (100) are used to fix a position sensor to receive signals depending on which position the withdrawable unit stays in the functional unit compartment.

Claims

27

1. A withdrawable unit adapted in a functional unit compartment of a low-voltage switchgear or controlgear assembly, having a synchronized movable operating handle mechanism with gravity-loaded handle locks and handle stoppers, a push button operated unlocking mechanism, an isolated lockable mechanism and a unit release mechanism, comprising: a. two push and hold locking devices (20) each fixed internally to the left sidewall (3) and top wall and the right sidewall (4) and top wall of the withdrawable unit (1), each of the push and hold locking device (20) comprising: i. a push button (12) loaded with spring (12a), ii. two lock plates (21 and 22) each having a head (21a or 22a) and a rod (21b or 22b), iii. a release pin (23) with a step (23b), inserted through a spring (23c), and a bracket (23a) with a guide bush (23d) and retained by a nut (23e) enabling the release pin (23) slightly spring-loaded and freely moveable inside the guide bush (23d), iv. a movable plate (24) having guide slots (24a) and key-hole type slot (24b), and of which the front end is bent at right angle and connected to a trigger plate (25) having top and bottom edges (25a and 25b) are tapered and horizontally straight, and v. top lifting release plate (26) with a square slot (26c) welded to a bracket(26a) fixed to the left or right sidewall of the withdrawable unit enabling to move up and down, and bottom lifting release plate (27) with a square slot (27a) and lock pins (34c and 35c), fixed to the left or right sidewall of the withdrawable unit, enabling to move up and down; b. two movable operating handles (10) each of which made up of first section (10a) and second section (10b) connected together by rivets (10c) and internally fixed to the left sidewall (3) and the right sidewall (4) of the withdrawable unit by fixing means inserted through guide slots (lOd) in the first and the second section (10a and 10b) and each of which comprising: i. handle seal gaskets (11), ii. a gravity-loaded handle lock (16) located on the rear side of each movable operating handle (10) having a lock plate (16b) with two bended flaps (16d) and a lifting plate (16c), and two handle lock pins (16a) and two handle lock pins (16a), iii. two guide arms (40) each fixed to the top and the bottom corner of the second section (10b) of the movable operating handle (10) in a rotatable manner about fixing point (40f) and each guide arm (40) is made up of two sub-arms (40a and 40b) of which the last end of the second sub-arm (40b) is formed as a rectangular-shaped control plug stopper (41) with a tab (42) and a guide roller (32), iv. two handle stoppers (34 and 35) each of which having a locking slot (34a or 35a) with a lock hole (34bor 35b) located on the second section (10b), and v. a pin (74) and a series of holes (54) located vertically on the first section (10a) in equal distance; c. two synchronizing arms (51 and 52), a synchronizing rod (53) and an adjustable profile (55), all used for synchronizing the two movable operating handles (10), where each synchronizing arm (51 or 52) comprising two subarms (51a and 51b or 52a and 52b) of which one end of the sub-arms (51a or 52a) is fixed to the first section (10a) of the two movable operating handles (10) in a rotatable manner about the fixing point (51c or 52c) using the holes (54) on the first section (10a)and the other end of the sub-arm (51a or 52a) is joined to one end of the sub-arm (51b or 52b) in a rotatable manner about the fixing point (5 Id or 52d) and the other end of the sub-arm (51b or 52b) is welded to the synchronizing rod (53); and each end of the synchronizing rod (53) is also fixed to the adjustable profile (55) in a rotatable manner about a fixing point (53a); d. a unit release mechanism (60) comprising: i. a locking arm (61) with a locking tab (61a) having a tapered rear edge and a straight front edge, an operating point (61b), and a slot (64), whereby the locking arm (61) is spring loaded with a spring (62), freely rotatable around a pin (63) and rotation is limited by a pin (65) inserted through the slot (64), and ii. a cutout (66) for the locking tab (61a) and a cutout (67) for the operating point (61b) on the left sidewall of the withdrawable unit; e. insertion interlock (110) implemented using different arrangements of slotted round pins (111) and square pins (112) comprising: i. a bracket (115) with threaded holes to which slotted round pins (111) are fixed, and the bracket (115) is fixed outside the left or right sidewall of the withdrawable unit by screws (117), ii. a plate (113) with three round holes (119) in a row, to which the square pins (112) are fixed by lock nuts (118), and iii. a bracket (116) with a square hole and two round holes in each row, to which the plate (113) with the square pin (112) is fixed, and the bracket (116) is fixed to a frame member of the functional unit compartment by screws inserted through holes (114); f. a front door (13), a door holding plate (15) and a gasket (14) affixed to the back of the door holding plate (15), a handle seal gasket (11) fixed to the front end of each movable operating handle (10) and an adhesive gasket (17) affixed to the front of the door holding plate (15) around each handle slot (18) on the front side of the withdrawable unit; an isolate lockable position indicator (71), padlock holes (73) and cutouts (33) on the left and right sidewalls of the withdrawable unit; position sensor brackets (100) on the left or right sidewall; and a set of bottom wheels (50) at the left and the right bottom edges; and a spring-loaded control plug holder (43) with a tab (44) fixed at the rear side of the withdrawable unit; g. two upper rails (80) having two surfaces (80a and 80b) bended at right angle where longitudinal edge of the surface (80b) further bended at right angle making a longitudinal edge (80c) with a tapered end (82) and embossed fixing holes (87) on longitudinal surface (80b) of the upper rails (80), each comprising: i. a rectangular-shaped lock hole (88) on the longitudinal surface (80a), ii. a release plate (85) welded on the longitudinal surface (80b) having a tapered tab (85a), a tapered dip (85b) and a tapered tab(85c), iii. two guide blocks (83 and 84) fixed by screws to the surface (80b), iv. a stopper plate (89) welded to the longitudinal surface (80b), located towards the front side of the longitudinal surface (80b), v. a safety stopper (80d) located at the front end of the upper rail (80), and vi. spring steel plates (86) welded to the longitudinal surface (80b); h. two lower rails (90) having two surfaces (90a and 90b) bended at right angle where longitudinal edge of the surface (90b) further bended at right angle making a longitudinal edge (90c) with a tapered end (93) and embossed fixing holes (94) on longitudinal surface (90b), comprising: i. a rectangular-shaped lock hole (88) on the longitudinal surface (90a), ii. two guide blocks (83 and 84) fixed by screws to the surface (90b), iii. a blocking tab (92) welded to the longitudinal surface (90b), iv. a stopper plate (89) welded to the longitudinal surface (90b), located towards the front side of the longitudinal surface (90b), and v. spring steel plates (86) welded to the longitudinal surface (90b).

2. The withdrawable unit of Claim 1, wherein the gasket (14) affixed to the back of the door holding plate (15), the handle seal gaskets (11) fixed to the front end of each movable operating handle (10) and the adhesive gaskets (17) affixed to the front of the door holding plate (15) around the handle slot (18) seal the withdrawable unit (1) and the movable operating handles in a manner which improves the degree of protection (IP code) of the withdrawable unit against the dust and the water, when the withdrawable unit is fully inserted into the functional unit compartment and locked by the two gravity-loaded handle locks (16).

3. The withdrawable unit of Claim 1, wherein the two push and hold locking devices (20) lock and unlock the withdrawable unit (1) at the test position.

4. The withdrawable unit of Claim 1, wherein the bottom wheels (50) allow the withdrawable unit to move on the rails (90).

5. The withdrawable unit of Claim 1, wherein the push button (12) is connected to the movable plate (24) which is fixed to the left or right sidewall of the withdrawable unit in a freely movable manner forward or backward through guide slots (24a). 31 The withdrawable unit of Claims 1 and 5, wherein the keyhole-type slot (24b) on the movable plate (24), is made up of Section A (24c) and Section B (24d) where the Section A (24c) of the keyhole-type slot (24b) is circular and the Section B (24d) of the keyhole-type slot (24b) is an ob-round. The withdrawable unit of Claim 1, wherein the trigger plate (25) connected to the movable plate (24) is used to operate the lock plates (21 and 22) by means of the top lifting release plate (26) and the bottom lifting release plate (27). The withdrawable unit of Claim 1, wherein the head (21a or 22a) of the lock plate (21 or 22) has a tapered and horizontally straight top edge and vertically straight side edges whereby the lock plate (21 or 22) is easily pressed in one direction. The withdrawable unit of Claim 1, wherein the rod (21b or 22b) of the lock plate (21 or 22)is inserted through a spring (21c or 22c), a bracket (2 Id or 22d) fixed to the inside left sidewall (3) of the withdrawable unit (1), a guide bush (21e and 22e) riveted to the bracket (2 Id or 22d) and the top or bottom lifting release plate (26 or 27), and is retained by a nut (21f or 221) whereby the spring (21c or 22c) is held between the bracket (2 Id or 22d) and the head (21a or 22a)in a slightly spring-loaded manner and to freely move up and down inside the guide bush (21e or 22e). The withdrawable unit of Claims 1 and 9, wherein the top lifting release plate (26) is by default pulled up by the spring (21c) and is coupled with the spring-loaded lock plate (21) in a manner which the pressing of the spring-loaded lock plate (21) does not make any downward movement of the top lifting release plate (26). The withdrawable unit of Claims 1 and 9, wherein the bottom lifting release plate (27) is by default gravity-loaded; pulled down by the spring (22c); rests on the top edge (25a) of the trigger plate (25); and is coupled with the spring-loaded lock plate (22) in a manner which the pressing of the spring-loaded lock plate (22) does not make any upward movement of the bottom lifting release plate (27). 32

12. The withdrawable unit of Claim 1, wherein the top lifting release plate (26) and the bottom lifting release plate (27) are coupled together in a manner which allows the lifting release plates (26 and 27) to be moved up and down freely in slot (26e).

13. The withdrawable unit of Claims 1 and 12, wherein, by default, the top edge (27c) of the square slot (27a) on the bottom lifting release plate (27) rests on the tapered section of the top edge (25a) of the trigger plate (25); and the bottom edge (26d) of the square slot (26c) on the top lifting release plate (26) is contacted with the tapered section of the bottom edge (25b) of the trigger plate (25).

14. The withdrawable unit of Claim 1, wherein the release pin (23) is internally fixed to the bracket (23a) which is fixed to top wall of the withdrawable unit.

15. The withdrawable unit of Claims 1, 6 and 14, wherein the head (23f) of the release pin (23) passes through the keyhole-type slot (24b) on the movable plate (24) whereby, by default, the front edge of the step (23b) of the release pin (23) hits and stops at the inside edge of the Section B (24d) of the keyhole-type slot (24b), thereby the release pin (23) is further spring-loaded.

16. The withdrawable unit of Claims 1, 6 and 15, wherein the width of the Section B (24d) of the keyhole-type slot (24b) is slightly greater than the diameter of the head (23f) of the release pin (23).

17. The withdrawable unit of Claims land 15, wherein the diameter of the step (23b) of the release pin (23) is slightly greater than the diameter of the head (23 f) of the release pin (23).

18. The withdrawable unit of Claims land 6, wherein the diameter of the step (23b) of the release pin (23) is slightly lower than the diameter of the Section A (24c) of the keyhole-type slot (24b) enabling the release pin (23) to come out through Section A (24c).

19. The withdrawable unit of Claims 1, 6, 14 and 15, wherein the release pin (23) becomes depressed when the movable plate (24) moves backward in relative to the 33 release pin, (24) whereby Section A (24c) of the keyhole-type slot (24b) moves to the location of the release pin (23) enabling the step (23b) of the release pin (23) to come out through the Section A (24c) of the keyhole-type slot (24b)and hold the forward movement of the movable plate (24); thereby, the push button (12) is kept pressed and spring-loaded by the spring (12a).

20. The withdrawable unit of Claims 1 and 19, wherein once the movable plate (24) moves backward in relative to the release pin, the trigger plate (25) connected with the movable plate (24) is also moved backward; whereby, the top lifting release plate (26) is pulled downward by the bottom edge (25b) of the moving trigger plate (25), and the bottom lifting release plate (27) is lifted upward by the top edge (25a) of the moving trigger plate (25);thereby, the springs (21c and 22c) are further loaded and the lock plates (21 and 22) are pressed respectively.

21. The withdrawable unit of Claims 1, 6, 14 and 15, wherein once the release pin (23) is pressed inwards by the tapered tab (85a) or the tapered tab (85c) or by any other means, the step (23b) of the release pin (23) is moved inwards allowing the movable plate (24) to move forward by the loaded spring (26a); whereby, the Section B (24d) of the keyhole-type slot (24b) is brought to the location of the release pin (23) and the step(23b) rests at the inside edge of the Section B (24d) of the keyhole-type slot (24b); thereby, the push button (12) is depressed and the release pin (23) becomes pressed.

22. The withdrawable unit of Claims 1, 5, 9, and 21, wherein once the release pin (23) is pressed inwards by the tapered tab (85a) or the tapered tab (85c) or by any other means, the movable plate (24) moves forward with the trigger plate (25); whereby, the top lifting release plate (26) moves upwards; and the bottom lifting release plate (27) moves downwards; thereby, the top and bottom lock plates (21 and 22) are depressed outside the withdrawable unit (1).

23. The withdrawable unit of Claims 1, 5, 6, 9, 12 and 15, wherein, by default, the two release pins (23) are depressed; the four lock plates (21 and 22) and the two push buttons (12) are depressed state. 34

24. The withdrawable unit of Claims 1, 19 and 21, wherein once the push button (12) is pressed, the movable plate (24) moves backward; thereby, the release pin (23) becomes depressed; and the lock plates (21 and 22) become pressed.

25. The withdrawable unit of Claim 1, wherein, each movable operating handle (10) is fixed to the left sidewall and the right sidewall of the withdrawable unit in a movable manner towards backward and forward in relative to the withdrawable unit between the two ends of the guide slots (lOd).

26. The withdrawable unit of Claim 1 and 25, wherein one end of the first sub-arm (40a) is fixed to the top or bottom comer of the second section (10b) of the movable operating handle (10) in a rotatable manner about the fixing point (40f) while the other end of the first sub-arm (40a) and one end of the second sub-arm (40b) are connected together as a freely rotatable riveted joint about the fixing point (40c).

27. The withdrawable unit of Claim 1 and 26, wherein the second sub-arm (40b) is fixed to the left sidewall or right sidewall of the withdrawable unit as a freely rotatable joint about the fixing point (40e).

28. The withdrawable unit of Claim 1 and 26, wherein the guide roller (32) is fixed on to the control plug stopper (41) at the end of the second sub-arm (40b) of each guide arm (40), whereby each guide roller (32) comes out from the cutouts (33) on the left and the right sidewalls of the withdrawable unit.

29. The withdrawable unit of Claim 1, 26 and 28, wherein when the movable operating handles (10) are moved backward, the guide arms (40) are contracted to their minimum allowed length by folding the sub-arms (40a and 40b); thereby, the top and the bottom control plug stoppers (41) with the tab (42) and the guide roller (32) move upward and downward respectively on a circular path.

30. The withdrawable unit of Claim 1, 26 and 28, wherein when the movable operating handles (10) are moved forward, the guide arms (40) are extended to their maximum allowed length by unfolding the sub-arms (40a and 40b); thereby, the top and the 35 bottom control plug stoppers (41) with the tab (42) and the guide roller (32) move downward and upward respectively on a circular path.

31. The withdrawable unit of Claim 1, wherein the locking pin (34c or 35c) of the handle stopper (34 or 35), on the bottom lifting release plate (27), is a round pin with a flat side (34d or 35d) fixed to the bottom lifting release plate (27), facing the flat side parallel to the front side (2) of the withdrawable (1).

32. The withdrawable unit of Claim 1, wherein the lock hole (34b or 35b) of the handle stopper (34 or 35), on the second section (10b) of the movable operating handle (10), is an obround located vertically to the locking slot (34a or 35a), where the vertical length of the obround is shorter than the horizontal length of the locking slot (34a or 35a).

33. The withdrawable unit of Claims 1, 31 and 32 wherein the forward movement of the movable operating handles (10) slid the locking slots (34a and 35a)in relative to the lock pins (34c and 35c)whereby the lock pins (34c and 35c) reach the lock holes (34b and 35b) and fall into the lock holes (34b and 35b) and get locked as the bottom lifting release plate (27) is pulled down by the spring (21c) and the gravity load of the bottom lifting release plate (27); thereby, the movable operating handles (10) get locked.

34. The withdrawable unit of Claims 1, 31, 32 and 33 wherein the shape of the lock pin (34c or 35c) and the lock hole (34b or 35b) prevent the slipping of the movable handle (10) when the movable operating handle (10) is pushed backward.

35. The withdrawable unit of Claims 1, 31, 32 and 33 wherein the pressing of the push buttons (12) pulls up the bottom lifting release plate (27) by the trigger plate (25) whereby the lock pins (34c and 35c) move upward from the lock holes (34b and 35b); thereby, the movable operating handle (10) are unlocked and can be moved backward until the movable operating handles (10) are locked by the gravity -loaded handle locks (16). 36

36. The withdrawable unit of Claim 1, wherein the two movable operating handles (10) are mechanically joined to each other in order to synchronize the other handle when one handle is pushed-in or drawn-out.

37. The withdrawable unit of Claims 1 and 36, wherein the folding of either of the synchronizing arms (51 or 52) rotates the synchronizing rod (53) about the fixing point (53a) and unfolding either of the synchronizing arms (51 or 52) rotates the synchronizing rod (53) about the fixing point (53a) to the opposite direction.

38. The withdrawable unit of Claims 1, 36 and 37, wherein the forward or backward movement of one movable operating handle (10), the synchronizing arm (51 or 52)fixed to that movable operating handle (10) unfolds or folds respectively, rotating the synchronizing rod (53); whereby, the other synchronizing arm (52 or 51) fixed to the other end of the synchronizing rod (53) also respectively unfolds or folds simultaneously, moving the other movable operating handle (10) fixed to the synchronizing arm (52 or 51).

39. The withdrawable unit of Claims 1, 36, 37 and 38, wherein the synchronization of the two movable operating handles (10) prevents the withdrawable unit being damaged when the user pushes-in or draws-out the withdrawable unit only from one movable operating handle (10).

40. The withdrawable unit of Claim 1, wherein a series of holes (15a) are located vertically along the rear side of the door holding plate (15) in equal distance, whereby the adjustable profile (55) is fixed to the door holding plate (15) using screws (55a) inserted through holes (15a).

41. The withdrawable unit of Claims 1 and 40, wherein the distance between two holes (15a) in the series of holes (15a) located vertically along the rear side of the door holding plate (15), is equivalent to the distance between two holes (54) in the series of holes (54) located vertically on the first section (10a) of each movable operating handle (10). 37

42. The withdrawable unit of Claims 1 and 41, wherein the two series of holes (15a and 54) are used to adjust the position of the two synchronizing arms (51 and 52) and the synchronizing rod (53) whenever the synchronizing rod (53) obstructs the installation of other equipment inside the withdrawable unit.

43. The withdrawable unit of Claims 1, wherein the distance existing between the two guide blocks (83 and 84) and the distance between the guide block (83) and the stopper plate (89), are equivalent.

44. The withdrawable unit of Claims 1, wherein the upper rails (80) and the lower rails (90) are fixed to frame members in the functional unit compartment using screws inserted through embossed fixing holes (87 and 94) on the longitudinal surfaces (80b and 90b) respectively.

45. The withdrawable unit of Claim 1, wherein the upper and the lower rails (80 and 90), each of which the front side is identified by a debossed arrow (81 and 91) and are used to guide and accommodate the withdrawable unit in its functional unit compartment of a controlgear and switchgear assembly.

46. The withdrawable unit of Claim 1, wherein the height of the guide block (83) is smaller than the height of the guide block (84) and the width of the guide block (83) is greater than the width of the guide block (84).

47. The withdrawable unit of Claim 1, wherein gravity-loaded handle lock (16) of which the lifting plate (16c) is welded to the lock plate (16b) towards the top section from the center of the lock plate (16b); the two handle lock pins (16a) are fixed to the front side of the door holding plate (15); and the lock plate (16b) with two bended flaps (16d) is fixed to the movable operating handle (10) in a vertically slidable manner.

48. The withdrawable unit of Claims 1 and 47, wherein the fully insertion of the movable operating handles (10) into the withdrawable unit brings the movable operating handles (10) as closest as possible to the door holding plate (15) while the flaps(16d) of the gravity -loaded handle locks (16) are lifted up by the tapered heads(16e) of the lock pins (16a)and at the highest end of the tapered heads (16e)the flaps (16d) are 38 dropped down and engaged with the lock pins (16a); thereby, the movable operating handles (10) are locked by the gravity-loaded handle lock (16). The withdrawable unit of Claims 1, 48 and 33, wherein the movable operating handles (10) are two-way lockable by the gravity-loaded handle locks (16) when the movable operating handles (10) are fully pushed into the withdrawable unit (1); and by the handle stoppers (34 and 35) when the movable operating handles (10) are fully drawn out from the withdrawable unit (1). The withdrawable unit of Claim 1, wherein the withdrawable unit is in the default state when completely removed from functional unit compartment, whereby the push buttons (12) are depressed; the lock plates (21 and 22) are depressed; the release pins (23) are pressed; the movable operating handles (10) are drawn out and locked by the handle stoppers (34 and 35); the control plug stoppers (41) together with guide rollers (32) have moved inward towards each other. The withdrawable unit of Claims 1 and 50, wherein the inwardly moved guide rollers (32) hit the guide blocks (84) on the upper and lower rails (80 and 90) and stop the withdrawable unit at the test position when the withdrawable unit is inserted into functional unit compartment, whereby the lock plates (21 and 22) are depressed into the rectangular-shaped lock holes (88) on the longitudinal surfaces (80a and 90a) in the upper and the lower rails (80 and 90); the release pins (23) are in pressed state at the tapered dips (85b) on the release plates (85); thereby, the withdrawal unit is locked at the test position. The withdrawable unit of Claim 1, wherein the two push buttons (12) are pressed to unlock the withdrawal unit at the test position, there by the movable operating handles (10) are unlocked and movable backward; the release pins (23) get depressed; the push button (12) becomes spring-loaded and is held in the pressed state; and the lock plates (21 and 22) are pressed inside the withdrawable unit. The withdrawable unit of Claim 1 and 52, wherein, at the test position, when the two movable operating handles (10) are unlocked by pressing the push buttons (12) and are moved backward, the guide rollers (32) are moved outwards from each other 39 further into the gaps between the guide blocks (83 and 84) on the upper and the lower rails (80 and 90) and the withdrawable unit (1) is moved towards the connected position.

54. The withdrawable unit of Claim 1, 52 and 53, wherein once the withdrawable unit (1) is unlocked at the test position, the withdrawable unit can be pushed in towards the connected position or drawn out until unit release mechanism stops the withdrawable unit (1).

55. The withdrawable unit of Claim 1, 52 and 53, wherein once the withdrawable unit is unlocked at the test position and as soon as is pushed in by the movable operating handles (lO)towards the connected position from the test position, the release pin (23) hits and get pressed by the tapered tab (85c), whereby the lock pins (34c and 35c) fall on the locking slots (34a and 35a); the lock plates (21 and 22) become depressed; the release pins (23) become pressed; and the push buttons (12) become depressed.

56. The withdrawable unit of Claims 1, 52, 53 and 55, wherein once the withdrawable unit is unlocked at the test position and as soon as is pushed in by the movable operating handles (10) towards the connected position from the test position, the unlocked movable operating handle (10) moves backward whereby the lock pins (34c and 35c) slid away from the locking holes (34b and 35b) through locking slots (34a and 35a); and the outwardly moving guide rollers (32) allow the withdrawable unit (1) to move to the connected position by means of the allowance created by folding the sub-arms (40a and 40b) while the guide rollers (32) stay in between the two guide blocks (83 and 84).

57. The withdrawable unit of Claims 1, and 56, wherein at the connected position the operating handles (10) are fully slid into the withdrawable unit through guide slots (lOd) and the guide arms (40) are folded to the maximum where the guide rollers (32) rest between the stoppers (83 and 84), and the withdrawable unit (1) is fully inserted into its functional unit compartment; thereby, the movable operating handles (10) reach the door holding plate (15) and are locked by the gravity-loaded handle locks (16). 40

58. The withdrawable unit of Claims 1, and 57, wherein at the connected position the handle seal gasket (11) and the adhesive gasket (17) on the door holding plate (15) are properly sealed by the gravity -loaded handle lock (16), thereby the withdrawable unit (1) is protected from the ingress of dust and water from the movable operating handles (10).

59. The withdrawable unit of Claims 1, and 56, wherein at the connected position the lock plates (21 and 22) are depressed; the release pins (23) are pressed; and the operating handles are locked by the gravity-loaded handle locks (16).

60. The withdrawable unit of Claims 1, and 59, wherein at the connected position, to unlock the withdrawable unit, the bended flaps (16d) on the lock plates (16b) at the two ends of each gravity-loaded handle lock (16), are dis-engaged from the lock pins (16a) by manually sliding up the lock plates (16b) from the lifting plates (16c) and the withdrawable unit is drawn out from the movable operating handles (10); whereby, the movable operating handles (10)are drawn out and get locked by the handle stoppers (34 and 35) while the two release pins (23) are pressed; the two push buttons are depressed; and the lock plates (21 and 22) are depressed.

61. The withdrawable unit of Claims 1, and 60, wherein, the drawing out the withdrawable unit from the movable operating handles (10) from the connected position, unfolds the guide arms (40) while the guide rollers (32) hit and exert force on the guide blocks (84) on the upper and the lower rails (80 and 90); thereby, the reverse force generated on the withdrawable unit pushes the withdrawable unit to be moved forward against the plugging load at the connected position.

62. The withdrawable unit of Claims 1, 59, 60 and 61, wherein, unlocking and drawing out the withdrawable unit from the movable operating handles (10) from the connected position, locks the withdrawable unit at the test position by means of the lock plates (21 and 22) depressing into rectangular-shaped lock holes (88).

63. The withdrawable unit of Claims 1, 52 and 62, wherein, once the withdrawable unit is unlocked at the test position and as soon as drawn out from the test position by the movable operating handles (10) towards the connected position from the test position, 41 the release pins (23) hit and get pressed by the tapered tab (85a), thereby the lock plates (21 and 22) are depressed; the release pins (23) are pressed; the push buttons are depressed.

64. The withdrawable unit of Claims 1, wherein the withdrawable unit is brought to the isolated lockable position by drawing out from the test position or inserting into the functional unit compartment, until the isolate lockable position indicator (71) on the left and the right sidewalls of the withdrawable unit (1) come to the functional unit compartment level.

65. The withdrawable unit of Claims 1 and 64, wherein at the isolate lockable position the push buttons (12) are pressed to unlock the movable operating handles (10) from the handle stoppers (34 and 35) and the movable operating handles (10) are fully pushed in and locked by the gravity-loaded handle locks (16), thereby the sub-arms (40a and 40b)are folded and the guide rollers (32) are moved into a gap (72) between the stopper plate (89) and the guide block (83) on the upper and lower rails (80 and 90).

66. The withdrawable unit of Claims 1 and 65, wherein the movable operating handles (10) of the withdrawable unit is further locked at the isolate lockable position using a padlock inserted through the two padlock holes (73) on the left or right sidewall (3) of the withdrawable unit (1), whereby the inserted padlock hits the pin (74) on the first Section (10a) of the movable operating handle (10) and blocks the movement of the movable operating handle (10).

67. The withdrawable unit of Claims 1 and 66, wherein the withdrawable unit is unlocked at the isolated lockable position by unlocking and removing the padlock inserted through the padlock holes (73); unlocking the movable operating handles (10) from the gravity-loaded handle locks (16); and drawing out the movable operating handles (10); whereby the withdrawable unit is pushed in towards the test position or drawn out of the functional unit compartment.

68. The withdrawable unit of Claim 1, wherein the gravity-loaded handle locks (16) are used to lock the withdrawable unit at the connected position and the isolated lockable position whereby the movable operating handles (10) are locked by the gravity -loaded 42 handle locks (16) while the sub-arms (40a and 40b) are folded to their maximum; thereby, the guide rollers (32) rest in the gap between the guide blocks (83 and 84) on the upper and the lower rails (80 and 90) at the connected position and the guide rollers (32) rest in the gap between the stopper plate (89) and the guide block (83) on the upper and lower rails (80 and 90) at the isolated lockable position.

69. The withdrawable unit of Claim 1, wherein the locking arm (61) of the unit release mechanism (60) is spring loaded in a manner whereby the locking tab (61a) and operating point (61b) come out through the cutouts (66 and 67) respectively; thereby, when the withdrawable unit is drawn out, the locking tab (61a) of the locking arm (61) hits and stops at the blocking tab (92) on the lower rail (90), at which point the operating point (61b) is pressed inward by a finger to draw out the withdrawable unit; and the tapered edge of the locking tab (61a) hits and is pressed inside by the blocking tab (92) when the withdrawable unit is inserted to the functional unit compartment.

70. The withdrawable unit of Claim 1, wherein when the withdrawable unit is inserted into the functional unit compartment while the push buttons (12) are pressed, the release pins (23) hit the safety stopper (80d) on the upper rails (80) and prevent the withdrawable unit being further inserted into the functional unit compartment, thereby the withdrawable unit is protected from possible damages resulting in due to unintended wrong push button (12) operation.

71. The withdrawable unit of Claims 1 and 70, wherein when the withdrawable unit is inserted into the functional unit compartment while the push buttons (12) are pressed, the withdrawable unit is drawn out of the functional unit compartment and the movable operating handles are fully drawn out and the release pins (23) are pressed by finger to bring the lock plates (21 and 22) and the push buttons (12) to depressed state.

72. The withdrawable unit of Claims 1, 28 and 29, wherein at the test position the tab (44) on the control plug holder (43) hits the tab (42) on the control plug stopper (41) and blocks the forward movement of the spring-loaded control plug holder (43). 43

73. The withdrawable unit of Claims 1, 28 and 29, wherein when the withdrawable unit is pushed in from the test position to connected position by the unlocked movable operating handle (10), the corresponding control plug stopper (41) rotates outward unblocking the tab (44) on the control plug holder (43) enabling the control plug holder (43) to move forward in relative to the withdrawable unit, thereby at the connected position the spring-loaded control plug holder (43) reaches it is maximum towards the front.

74. The withdrawable unit of Claims 1, 28, 29 and 73, wherein when the withdrawable unit is moved from the connected position to the test position, the spring-loaded control plug holder (43) moves backward and reaches the maximum towards the back in relative to the withdrawable unit while the corresponding control plug stopper (41) with the tab (42) rotates inwards as the movable operating handles (10) are moved forward, thereby the tab (44) passes the tab (42) of the control plug stopper (41) allowing the tab (42) to move to the blocking position again at the test position.

75. The withdrawable unit of Claim 1, wherein the insertion interlock (110) of which each square pin (112) with the plate (113) is inserted into a square hole on the bracket (116) to make the matching arrangement of square pins (112) and fixed to the bracket (116) by a screw inserted into either of the remaining two round holes (119) on the plate (113) in a zig-zag manner, thereby the square pins (112) are fixed closer to each other to increase the number of combinations.

76. The withdrawable unit of Claims 1 and 75, wherein the insertion interlock (110) of which the arrangement of slotted round pins (111) fixed on the withdrawable unit and the arrangement of square pins (112) fixed on the bracket (116) are arranged in a manner which allows one arrangement of slotted round pins (111) to pass through the relevant arrangement of square pins (112).

77. The withdrawable unit of Claims 1 and 76, wherein the insertion interlock (110) prevents inserting of a withdrawable unit into a wrong functional unit compartment before it gets locked at the test position. 44

78. The withdrawable unit of Claim 1, wherein the position sensor bracket (100) is used to fix a position sensor to receive a signal depending on which position the withdrawable unit stays in the functional unit compartment

79. A method adapted for inserting and removing a withdrawable unit adapted in a functional unit compartment of a low-voltage switchgear or controlgear assembly, having a synchronized movable operating handle mechanism with gravity-loaded handle locks and handle stoppers, a push button operated unlocking mechanism, an isolated lockable mechanism and a unit release mechanism, as claimed in Claim 1, such method comprising steps of: a. Fixing upper rails (80) and lower rails (90) in functional unit compartment of low-voltage switchgear or controlgear assembly, using embossed fixing holes (87 and 94), keeping the debossed arrows towards the front side of the functional unit compartment; b. Fixing the bracket (115) with pre-fixed slotted round pins (111) of the insertion interlock (110) in a specific arrangement, to the right or left sidewall of the withdrawable unit as per the design requirement; c. Fixing the bracket (116) with pre-fixed plates (113) and square pins (112) of the insertion interlock (110) in a specific arrangement which allows to pass only through the specific arrangement of slotted round pins (111) in above Step b., whereby the bracket is fixed to a suitable frame member in the functional unit compartment; d. Inserting the correct withdrawable unit into the functional unit compartment while the push buttons (12), the lock plates (21 and 22), movable operation handles (10) and the release pins (23) are in their default states, i.e. the push buttons (12) are in the depressed state; the lock plates (21 and 22) are in the depressed state; the movable operating handles (10) are fully drawn out and locked by the handle stoppers (34 and 35) and the release pins (23) are in the pressed state; 45 e. Inserting the withdrawable unit into the functional unit compartment while the push buttons (12) are pressed, whereby the withdrawable unit can only be inserted until the release pins (23) hit the safety stoppers (80d) which prevent the withdrawable unit being further inserted into the functional unit compartment, thereby the withdrawable unit is drawn out and the release pins (23) are pressed by a finger to bring the withdrawable unit to default state, f. Inserting the withdrawable unit until the test position, whereby the withdrawable unit is locked at the test position by means of the lock plates (21 and 22) being pressed into rectangular-shaped lock holes (88) on the longitudinal surfaces (80a and 90a) on the upper and lower rails (80 and 90); g. Unlocking the withdrawable unit by pressing the push buttons (12) at the test position whereby the movable operating handles (10) are unlocked from the handle stoppers (34 and 35) and the movable operating handles (10) are pushed in to move the withdrawable unit towards the connected position, or he movable operating handles (10) are drawn out from the test position to remove the withdrawable unit from the functional unit compartment until the withdrawable unit is stopped by the unit release mechanism; h. Having pressed the push buttons (12), when the withdrawable unit is pushed in towards the connected position or drawn out from the test position from the movable operating handles (10), the release pins (23) are pressed in respectively by the tapered tabs (85c) or the tapered tabs (85a) on the upper rails (80), whereby the forward movement of the movable plates (24) bring the lock plates (21 and 22) and the push buttons (12) to depressed state; i. Inserting the withdrawable unit into the functional unit compartment until the connected position by the movable operating handles (10), whereby the movable operating handles (10) are fully pushed in and locked at the connected position by means of the gravity-loaded handle locks (16) and thereby the withdrawable unit is locked at the connected position; 46 j. Unlocking the withdrawable unit at the connected position by sliding up the lock plate (16b) from the lifting plate (16c) of the gravity-loaded handle lock (16) and drawing out the withdrawable unit towards the test position from the movable operating handles (10) until the withdrawable unit is locked at the test position, thereby the movable operating handles are drawn out and locked by the handle stoppers (34 and 35); k. Unlocking the withdrawable unit at the test position by pressing the push buttons (12) and drawing out the withdrawable unit from the movable operating handles (10), thereby the movable operating handles get locked by the handle stoppers (34 and 35) and the withdrawable unit gets stopped by the unit release mechanism (60); l. Pressing the operating point (61b) of the unit release mechanism (60) inwards by a finger and drawing out the withdrawable unit from the functional unit compartment when it gets stopped by the unit release mechanism (60). m. In the event of carrying out any maintenance work, below Steps from n. to p. are followed. n. Unlocking at the test position and drawing out or inserting the withdrawable until the isolate lockable position indicator (71) on the left or right sidewall reaches the functional unit compartment level, i.e. isolated lockable position, and pressing the push buttons (12) to unlock the movable operating handles (10) from the handle stoppers (34 and 35) and pushing in the movable operating handles (10) until they (10) reach the door holding plate (15) and locking them (10) by the gravity-loaded handle locks (16); o. Inserting a padlock through padlock holes (73) on the left or right sidewall (3) of the withdrawable unit to further lock the movable operating handles (10) at the isolated lockable position. p. Unlocking the withdrawable unit at the isolated lockable position by unlocking and removing the padlock from the padlock hole (73) and unlocking the 47 gravity-loaded handle locks (16) and drawing out the movable operating handles (10) until they (10) get locked by the handle stoppers (34 and 35) whereby the withdrawable unit is pushed in towards the test position or drawn out until stopped by the unit release mechanism (60).