WO2021130529A1

WO2021130529A1 - Four pole outgoing plugging assembly

Info

Publication number: WO2021130529A1
Application number: PCT/IB2019/061395
Authority: WO
Inventors: Peter Alexeev
Original assignee: Elsteel (Private) Limited
Priority date: 2019-12-27
Filing date: 2019-12-27
Publication date: 2021-07-01
Also published as: EP4082081A1; EP4082081C0; EP4082081B1; AU2019480471A1

Abstract

The invention is a plugging assembly comprising a male plug and a matching female plug used to interconnect functional unit and external cables in low-voltage switchgear. Depending on the location of the female plug the invention discloses two variations namely 'side-access' and 'rear-access'. The invention provides facility to connect to external cables with an improved cable protection mechanism. The invention also provides separate connector per phase to wire an indicator on the front cover of the low-voltage switchgear.

Description

TITLE

Four pole outgoing plugging assembly

TECHNICAL FIELD The present invention relates to the field of low-voltage power distribution control centers and motor control centers, particularly with regard to plug-in connections used to connect electrical equipment installed in functional units (withdrawable or removable units) in low- voltage switchgear and controlgear, to external cables. BACKGROUND ART

Low-voltage switchgears are intended to distribute electrical power to consumers. The terms such as low-voltage switchgear or controlgear assemblies are used interchangeably to identify low-voltage switchgears in the industry. Low-voltage switchgears are internally separated into compartments, sub-sections and sections depending on the application requirements. Typical low-voltage switchgear consists of compartments for busbars, functional units and terminals, and external cables.

The separations between each compartment, section or sub-section of a low-voltage switchgear is achieved by introducing partitions and barriers.

A type of internal separation depends on the application requirements. International standard IEC 61439-2 has classified such separations into four main forms of internal separation depending on partitions and barriers between compartments. Form 1 does not offer any separations between busbars, functional units and terminals for external cables. Form 2 offers separations of busbars from functional units. Terminals for external cables can be separated from busbars and functional units or not. Form 3 offers separations of busbars from functional units, functional units from each other and terminals for external cables from functional units. Terminals for external cables can be separated from busbars or not. Form 4 offers separation of busbars from functional units and terminals for external cables, functional units from each other and terminals for external cables of each functional unit from each other. Terminals for external cables can be separated from functional units or not. Thus, an internal separation protects equipment and operating personnel in case of failures inside low-voltage switchgear.

Interconnection between functional units, busbars and terminals for external cables becomes very important. Therefore, low-voltage switchgear builders have devised various technologies to interconnect functional units, busbars and terminals for external cables.

When high form of internal separation (Porm 3 or 4) is achieved low-voltage switchgear builders come across a problem of making interconnection between functional units, busbars and terminals for external cables. A functional unit needs to be connected with distribution busbars to distribute electrical energy to the terminals for external cables. Similarly, the external cables need to be connected to the terminals of the unit while maintaining easy removability of the functional unit from the low-voltage switchgear.

Low-voltage switchgear builders use different kinds of connection methods in order to achieve this removable interconnectivity between controlling devices and the external cables. One such mechanism closest to this invention, is disclosed in PCT/IB2013/001597 and patented under EP2875551. In that invention a different type of plugging technology is disclosed to make interconnections with respect to power, control and data connections. The operational current of that invention was limited due to the size of the plug pins.

TECHNICAL PROBLEM

Due to the partitions and barriers between the compartments, high packing density of equipment inside the compartments and limited space in the compartments, the low-voltage switchgear manufacturers find it difficult to make such interconnections.

On the other hand, the low-voltage switchgear manufacturers cannot compromise the protection offered by the internal separation, since the safety of the personnel working around the low- voltage switchgear is one of the most demanding requirements in the industry.

Power supply interruption time is also one of the most critical parameters for the industry. In case of maintenance or repair work on one of functional units, other units should stay live. The removal of the functional unit should be as easy as possible. The technicians are not expected to dismantle conductors inside the unit before it is taken out as well as external cables. Another phenomenon in the industry is that the end users look for compact components having high operating currents in order to achieve higher packing density.

DISCLOSURE OF THE INVENTION The invention is a plugging assembly comprising a male plug and a matching female plug used to interconnect outgoing power circuits of functional unit with external cables in cable compartment of low-voltage switchgear. Depending on the location of the female plug and cable compartment, the invention discloses two variations namely side-access and rear-access. The invention provides facility to connect external cables with an improved cable protection mechanism. The invention also provides a separate terminal for each pole to wire an indicator.

ADVANTAGEOUS EFFECTS

The invention eliminates the requirement of disconnection and/or dismantling external cables during removal of a functional unit from the low-voltage switchgear. The number of cables per phase has been increased which in turn increases the operating current of functional unit.

The invention enables functional units to be taken out entirely from the low-voltage switchgear and replace while the low-voltage switchgear is live.

The cable connections can be arranged as per the requirements of the application as the invention supports alternative ways of cable connections from rear or side cable compartments with respect to functional unit compartment, where the external cables are accessed from a separate compartment.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is an illustration of the first variation of the invention, i.e. side access plugging assembly comprising male plug and female plug.

Fig. 2A is an illustration of the male plug of the plugging assembly.

Fig. 2B is an illustration of bottom view of the male plug of the plugging assembly.

Fig. 2C is an illustration of the height levels of the ‘U’ shaped spring-loaded clips of the male plug.

Fig. 3 is an illustration of the female plug of the side access plugging assembly and its sides as referenced in the description.

Fig. 4 is an illustration of the main components of the female plug and the internal conductors placed in the housing of the female plug.

Fig. 5 is an illustration of the top view and the side view of internal conductor placed in the housing of the female plug.

Fig. 6 is an illustration of the front surface of the top cover of the female plug.

Fig. 7 is an illustration of the back of the top cover and the housing of the female plug.

Fig. 8 is an illustration of the right side of the housing of the female plug.

Fig. 9 is an illustration of the bottom of the housing of the female plug.

Fig. 10 is an illustration of the mounting bracket and how the female plug is mounted to the mounting bracket.

Fig. 11 is an illustration of the second variation of the invention, i.e. rear access plugging assembly comprising male plug and female plug.

Fig. 12 is an illustration of the female plug of the rear access plugging assembly and its sides as referenced in the description.

Fig. 13 is an illustration of the female plug without its top cover and the internal conductors placed in the housing of the female plug. Fig. 14A is an illustration of an internal conductor placed in the housing of the female plug of the second variation.

Fig. 14B is an illustration of angular location of external cable connector screw holes and their respective external cable connector holes in an internal conductor with respect to bottom of the housing of the female plug of the second variation.

Fig. 15 is an illustration of the right side of the housing of the female plug of the second variation.

Fig. 16 is an illustration of the left side of the housing of the female plug of the second variation.

Fig. 17 is an illustration of front surface of the top cover of the female plug of the second variation.

Fig. 18 is an illustration of the back of the top cover and the housing of the female plug of the second variation.

Fig. 19 is an illustration of the bottom of the housing of the female plug of the second variation.

Fig. 20 is an illustration of the mounting bracket and how the female plug is mounted to the mounting bracket in the second variation.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

The invention is a plugging assembly which allows connecting or disconnecting of functional unit of the low-voltage switchgear from external cables connected with the consumer, by means of a plugging in mechanism. The plugging assembly comprises a male plug and a female plug.

The invention discloses two variations of such plugging assemblies: side-access and rear- access, depending on the location of the female plug and cable compartment.

Fig. 1 shows the first variation of the invention, i.e. the plugging assembly (1) comprising male plug (2) and female plug (3), where external cables are connected from the right side of the female plug (3) and the male plug (2) is plugged in from the top of the female plug (3). This plugging assembly (1) is identified as ‘side-access outgoing plug’ by the inventor.

As shown in Fig. 2A, the male plug (2) of the plugging assembly (1) consists eight TP shaped spring-loaded clips (4) and their corresponding four terminals (5) meant for internal wiring, fixed on a rigid housing (6) made of insulating material, and is fixed in a functional unit in low-voltage switchgear. Since clips (4) are spring-loaded, they are expandable and shrinkable when they are engaged and disengaged solid conductive matter. The spring on the spring- loaded clip (4) improves the reliability of electrical contact. Each ‘U’ shaped spring-loaded clip (4) is accommodated in and supported by a base (7) protruded downwards from the housing (6). The housing (6) of the male plug (2) has a set of fixing holes (6a) to fix the male plug (2) in a functional unit. The male plug (2) is fixed in manner which extends out its ‘U’ shaped spring-loaded clips (4) towards the rear side of the unit allowing the spring-loaded clips (4) to be mechanically inserted into the female plug (3) when the unit is pushed into its compartment in the low-voltage switchgear. The terminals (5) are internally wired with the devices inside the unit. Each of the terminals (5) is covered from three insulated barriers (8) protruded upwards from the housing (6), which limit access to live parts - terminals (5). Furthermore, as shown in Fig. 2B, each terminal (5) is connected to two ‘U’ shaped spring- loaded clips (4). As shown in Fig. 2C, two spring-loaded clips (4) connected to each terminal (5) are designed to be in two different heights, creating two levels of spring-loaded clips (4) for a terminal (5) to avoid connecting or disconnecting all clips (4) at the same time to and from receiving terminals of internal conductors in the female plug (3). As a result, all spring- loaded clips (4) in the male plug (2) are not engaged or disengaged from receiving terminals of internal conductors in the female plug at the same time. Thus, when the unit is pushed into and removed from its compartment, the effort to be deployed against mechanical force due to springs in the clips (4) is reduced. The male plug (2) is dedicated to the three phases and the neutral in the power supply.

The female plug (3) of the plugging assembly (1) is the component which receives the ‘U’ shaped spring-loaded clips (4) of the male plug (2) and contains terminals for connection of the external cables.

For the ease of description, the sides of the female plug (3) is referenced as top side (9), bottom side (10), left side (11) and right side (12), as shown in Fig. 3.

As shown in Fig. 4, the female plug (3) consists of four internal conductors (13) placed inside a cuboid shaped rigid housing (14) and a top cover (15) moulded out of insulating material. The housing (14) with insulated internal ribs (16) with holders (17) and border walls (34) with holders (17) creates deep channels (18) with holders (17) to guide and accommodate the internal conductors (13) in the deep channels (18). The internal ribs (16) separate each of the internal conductors (13). The holders (17) hold the internal conductors (13) vertically and firmly in the deep channels (18). The housing (14) has four screw holes (19) on two of its border walls (34). The top cover (15) is fixed to the housing (14) by four screws driven into the screw holes (19). The four internal conductors (13) are meant for four poles, three phases and one neutral. Each internal conductor (13) is a solid block of copper which runs from the left side (11) to the right side (12) of the female plug (3).

As shown in Fig. 5, the internal conductor (13) has a rectangular shaped longitudinal profile on one end, and two external cable connector holes (20) and an indicator wire connector hole (21) on the other end which is identified as cable connector end. The rectangular shaped longitudinal profile acts as the receiving terminal (22) which is caught by the spring-loaded clip (4) of the male plug (2), whereas the external cable connector holes (20) and the indicator wire connector hole (21) act as the terminals meant for external cables. In order to accommodate two external cables in one terminal, the cable connector end of the internal conductor (13) in the female plug (3) is designed to have two external cable connector holes (20) having different depths and external cable connector screw holes (23) having different depths. The two separate external cable connector holes (20) are located on one top of the other at the cable connector end of the internal conductor (13). The external cable connector holes (20) are deep enough to properly hold the external cables. The depth of the lower external cable connector hole (20) is greater than the depth of the upper external cable connector hole (20). The two external cable connector screw holes (23) and an indicator wire connector screw hole (24) are located on the top of the cable connector end of the internal conductor (13). The two cable connector screw holes (23), having different depths, are kept in line next to each other, but are sunk into their respective cable connector holes (20) in the same internal conductor (13) in the housing (14) of the female plug (3). The set of cable connector screw holes (23) which sinks into the deeper external cable connector holes (20), has counterbores (25) in their top sections so that the external cable connector screws (26) are not driven from the top of the holes (23) and the screws (26) have same thread height. They (26) are riveted with clamps (27) at the thread end; therefore, they are kept inserted all the time in their screw holes (23) and can only be driven up or down. They (26) are used to fix external cables in the two external cable connector holes (20). The diameter of the external cable connector screws (26) are selected in manner which the required contact pressure on the cables can be applied to properly contact with the relevant surfaces and to firmly tighten the external cables. The clamp (27) riveted at the end of the external cable connector screw (26) increases the contact area with the external cable while holding the same and prevents possible damages to the external cable due to the screw (26) being over tighten into the external cable. The external cables are connected to the female plug (3) by inserting the external cables into the external cable connector holes (20) and tightening the screws (26).

Each terminal (5) in the male plug (2) has two ‘U’ shaped spring-loaded clips (4). Each internal conductor (13) in the female plug (3) can receive two spring-loaded clips (4) in the male plug (2), and accommodates two external cables connected to the load, whereby the total cross-sectional area of the internal and external cables connected to the load is increased. The internal conductor (13) has a certain thickness with a corresponding cross-sectional area. Thus, the plugging assembly is used to connect the power to the load connected to the external cables whereby each internal conductor (13) in the female plug (3) passes current to external cables. The indicator wire connector hole (21) is located closer to top left corner of the surface where the two external cable connector holes (20) are located, as shown in Fig. 5. A smaller screw is used to fasten the wire inserted into the indicator wire connector hole (21) in the female plug (3). The indicator screw is inserted into the hole (24). The wire connected to the indicator wire connector hole (21) in the internal conductor (13) which represents the neutral pole and other three internal conductors (13) which represent the three phases are intended to indicate power supply. As shown in Fig. 6, the top cover (15) is configured to have a set of openings (28) for ‘U’ shaped spring-loaded clips (4); set of openings (29) is intended for external cable connector screws (26); set of openings (30) is intended for indicator wire connector screws; set of openings (31) is intended for top cover fixing screws and set of screw holes (32) is intended for transparent Form 4B cover fixing screws. The openings (28) intended for spring-loaded clips (4) are shaped into thin rectangular with rounded corners, which resembles the shape of the base (7) of ‘U’ shaped spring-loaded clip (4). The size of the opening (28) is slightly greater than the size of the base (7) of the spring-loaded clip (4); thus, allowing the spring- loaded clips (4) and its base (7) to enter into the opening (28) and the spring-loaded clips (4) to reach and catch the internal conductor (13) in the housing (14) of the female plug (3). The shape of the base (7) is designed to have an inwardly tapered top (47) as shown in Fig. 2A. Similarly, the opening (28) for spring-loaded clip (4) is designed to have the same shape with a tapered bottom to facilitate the tapered top of the base (7) of the clip (4) reaches the tapered bottom of the opening (28) while the clip (4) fully engages with the internal conductor (13). A gap is maintained between the housing (6) of the male plug (2) and the front surface of the top cover (15) of the female plug (3) to protect the female plug (3) being hit by the male plug (2).

As shown in Fig. 7, the back of the top cover (15) has a configuration of channels (33) designed to be sunk into the internal ribs (16) and the three border walls (34) in the housing

(14) of the female plug (3) when the top cover (15) is placed on the top of the housing (14). At the top edges of the three border walls (34) of the housing (14), the border walls (34) have a step (36) on the outside of the border walls (34). When the top cover (15) is placed on top of the housing (14), the top edges of the internal ribs (16) and that of border walls (34) sink into the channels (33) at the back of the top cover, until the bottom of edges (35) of the top cover

(15) hit the step (36) on the border walls (34) of the housing (14). The top cover (15) is fixed to the housing (14) with screws driven into top cover fixing screw holes (19).

As shown in Fig. 8, the right side of the housing (14) has openings (37) for the external cables.

As shown in Fig. 9, at the bottom (10) of the housing (14) there is a spring clip (38) with a notch (39) and two mounting channels (40) on the two long edges which are used to mount the female plug (3). The spring clip (38) is positioned in the bottom of the housing (14) along the center line of the width of the housing (14). One end of the spring clip (38) is kept as a free end (46). As shown in Fig. 10, a rectangular steel mounting bracket (41) having a locking hole (42), a slide stopper (43) and mounting screw holes (44), is mounted horizontally on to a frame of the low-voltage switchgear in the functional unit compartment. Its long edges are formed as flanged edges (45) to allow sliding-in mounting channels (40) on the bottom (10) of the housing (14) of female plug (3). The female plug (3) is inserted through the two mounting channels (40) on its back along the flanged edges (45) of the bracket (41) and slided-in until the notch (39) reaches the locking hole (42) on the bracket and locks making a “click” sound, while one end of the spring clip (38) on the bottom hits the slide stopper (43) in the bracket (41). The female plug (3) is un-mounted from the bracket (41) by pressing the free end (46) of the clip (38) while sliding-out the female plug (3) from the bracket (41).

Once the female plug is (3) is mounted to the rectangular steel mounting bracket (41), the external cables which supply power to the load in the outgoing circuit, are inserted into the external cable connector holes (20) and fixed with screws (26). The indicator wires are inserted into indicator wire connector holes (21) and fixed them with wire connector screws driven into holes (24). Once all external cables and indicator wires have been connected, an ‘L’ shaped transparent Form 4B cover with cut-outs for external cables and indicator wires, is fixed using a set of screws driven into transparent Form 4B cover fixing screw holes (32). With reference to Fig. 6, one side of the transparent Form 4B cover covers until the openings (29) for external cable screws and openings (30) for indicator wire connector screws on the top cover (15) of the female plug (3), while the other side of the transparent Form 4B cover covers the openings (37) for external cables on the right side (12) of the female plug (3), with reference to Fig. 8. Thus, the transparent Form 4B cover avoids the accidental access or contact with live parts, i.e. external cable connector holes (20), external cable connector screws (26), indicator wire connector screws, etc.

When the functional unit is fully inserted into its compartment, the male plug (2) fixed in the unit engages its ‘U’ shaped spring-loaded clips (4) with the internal conductors (13) in the female plug (3) where the ‘U’ shaped spring-loaded clips (4) travel through the openings (28) for the ‘U’ shaped spring-loaded clips on the top cover (15) of the female plug (3), engaging rectangular shaped longitudinal ends of the internal conductors (13) from their top, and make power connections with female plug (3) mounted on the frame of the low-voltage switchgear. When the functional unit is removed from its compartment, the male plug (2) disengages its spring-loaded clips (4) from the internal conductors (13) and withdraws from the female plug (3) disconnecting the power connections. The above described variation of the invention - side access outgoing plug - makes the interconnection between the internal circuit and the outgoing circuit in the low-voltage switchgear, i.e. it connects the devices mounted in functional units with the external cables which supply power to the load in the downstream, where the external cables are connected to the female plug (3) from the compartment which is adjacent to the unit on the right or left. The female plug (3) is mounted horizontally on a vertical frame member in the low-voltage switchgear, facing its top side (9) towards the front of the low-voltage switchgear, keeping its openings (28) for ‘U’ shaped spring-loaded clips (4) in the functional unit compartment and the openings (37) for external cables extending out to the cable compartment located on the left or right of the functional unit compartment. As a result, the external cable connector holes (20) and the external cable connector screws (26) are accessed from the adjacent cable compartment located on the left or right of the functional unit compartment when connecting external cables to the female plug (3). Similarly, the indicator wire connector holes (21) and wire connector screws are also accessed.

The Fig. 11 shows another variation of the invention which is identified as ‘rear-access outgoing plug’. This plugging assembly (50) has the exactly same functionality as the first variation of the invention which was described above as the ‘side-access outgoing plug’. What mainly differ from the first variation are the openings and holes in the top cover; openings, holes and internal ribs in the housing and configuration of the internal conductor of the female plug (51). The same male plug (2) is used in the second variation (50).

For easy description, the female plug (51) of the second variation (rear-access outgoing plug) is referenced as top side (52), bottom side (53), left side (54) and right side (55) as shown in Fig. 12. The female plug (51) also consists of a cuboid shaped rigid housing (56) made out of a non-conductive material and a top cover (57).

As shown in Fig. 13, the female plug (51) also consists of four internal conductors (58) placed inside the housing (56) which is molded with insulating internal ribs (59) with holders (61) and border walls (85) with holders (61) creating deep channels (60) with holders (61) to guide and accommodate the internal conductors (58) in the deep channels (60). The deep channels (60) with holders (61) hold the internal conductors (58) vertically and firmly in the housing (56) of the female plug (51). The internal ribs (59) separate each of the internal conductors (58). The housing (56) has four top cover fixing screw holes (62) on the border walls (85). The top cover (57) is fixed to the housing (56) by tightening four screws into the top cover fixing screw holes (62).

Same as in the first variation (1) of the invention, the four internal conductors (58) meant for four poles, i.e. three phases and the neutral, provide the same functionality and has a rectangular shaped longitudinal profile of receiving terminal (63) on one end and two external cable connector holes (64), indicator wire connector hole (65) and their screw holes (66 and 68) on the other end, which is identified as cable connector end, as shown in Fig. 14. The internal conductor (58) runs from the left side (54) to the right side (55) of the female plug (51). The shape of the internal conductor (58) is slightly different from that of the first variation in order for them to have firmly fixed to the deep channels (60) and holders (61) in the housing (56). The ‘U’ shaped spring-loaded clip receiving terminal (63) is same as the first variation. But, it is caught by the spring-loaded clips (4) from a different direction, i.e. from the left side of the internal conductor (58). The two external cable connector holes (64), having different depths, are located next to each other on the internal conductor (58), facing the top cover (57). The external cable connector screw holes (66) have different depths and are kept in line next to each other. The external cable connector screw holes (66) are sunk into their respective cable connector holes (64) in the same internal conductor (58). The set of cable connector screw holes (66) which sinks into the deeper external cable connector holes (64) has counterbores in their top sections so that the external cable connector screws (67) are not driven from the top of the holes (66) and the screws (67) have same thread height. They (67) are riveted with clamps (86) at the thread end as shown in Fig. 14A. The external cable connector screw holes (66) and their screws (67) and indicator wire connector screw hole (68) and their screws are located on the right side of the internal conductor (58), facing the right side (55) of the housing (56) of the female plug (51). As shown in Fig. 14B, the external cable connector screw holes (66) and their respective external cable connector holes (64) are located in an angular manner with respect to bottom (53) of the housing (56), maintaining right angle between the two center axes of the external cable connector screw holes (66) and external cable connector holes (64).

As shown in Fig. 15, the right side (55) of the housing (56) is configured to have openings (69) for external cable connector screws (67); openings (70) for wire connector screws and screw holes (71) for fixing a transparent Form 4B cover. As shown in Fig. 16, the openings (72) for ‘U’ shaped spring-loaded clips (4) in the male plug (2) are located on the left side of the housing (56) of the female plug (51). The functions and the design of the openings (72) are same as for the first variation, i.e. the openings (72) for ‘U’ shaped spring-loaded clips (4) on the left side of the housing (56) are shaped into thin rectangular with rounded corners with a tapered bottom resembling the shape of the base (7) of ‘U’ shaped spring-loaded clip (4) and are sized slightly greater than the size of the base (7) of the ‘U’ shaped spring-loaded clip (4).

As shown in Fig. 17, the top cover (57) is configured to have a set of openings (73) for external cables and openings (74) for top cover fixing screws.

As shown in Fig. 18, the back of the top cover (57) has a configuration of channels (75) and the housing (56) of the female plug (51) has a matching configuration of insulating internal ribs (59). When the top cover (57) is placed on the top of the housing (56), the channels (75) on the back of the top cover (57) sink into the top edges of internal ribs (59) while the bottom edges (76) of the top cover (57) stop on the housing (56). Apart from the configuration of channels (75), the top cover (57) is provided with a set of slots (77) which accommodate the top edges of the internal conductors (58) when the top cover (57) is placed on the housing (56). The top cover (57) is fixed to the housing (56) with screws driven into top cover fixing screw holes (62) on the border walls (85) of the housing (56) through openings (74) meant for top cover fixing screws on the top cover (57).

As shown in Fig. 19, and as described for the first variation, the bottom (53) of the housing (56) of the second variation has a spring clip (78) with a notch (79) and two mounting channels (80) on the two long edges. The spring clip (78) is positioned in the bottom of the housing (56) along the center line of the width of the housing (56).

As shown in Fig. 20, a similar rectangular steel mounting bracket (81) having a locking hole (82), a slide stopper (83) and mounting screw holes (84), is used to mount the female plug (51) of the second variation, horizontally on to a vertical frame member of the low-voltage switchgear, facing the left side (54) of the female plug (51) towards the front side of the low- voltage switchgear in the functional unit compartment, in the same way as described for the first variation of the invention. Thus, the female plug (51) is mounted in a manner where the left side (54) of the female plug (51) stays in the functional unit compartment, keeping its (51) openings (72) for spring-loaded clips (4) in the functional unit compartment, while the openings (73) for external cables extend out inwardly to the cable compartment at the right back of the functional unit compartment of the low-voltage switchgear. As a result, the external cable connector holes (64) and the external cable connector screws (67) are accessed from the adjacent cable compartment, right back of the functional unit compartment, when connecting external cables to the female plug (51). Similarly, the indicator wire connector holes (65) and indicator wire connector screws are also accessed. Since external cable connector screw holes (66) and their respective external cable connector holes (64) are located in an angular manner at right angle inside the internal conductor (58), it allows the external cables to be easily inserted into external cable connector holes (64) and provides sufficient space to accommodate external cables in the cable compartment itself.

Once the female plug is (51) is mounted on a vertical frame member, the external cables which supply power to the load in the outgoing circuit, are inserted into the external cable connector holes (64) and fixed with screws (67). The indicator wires are inserted into indicator wire connector holes (65) and fixed them with indicator wire connector screws driven into holes (68) in all four internal conductors (58).

Once all external cables and indicator wires have been connected, an ‘L’ shaped transparent Form 4B cover with cut-outs for external cables and indicator wires, is fixed using a set of screws driven into cover fixing screw holes (71) shown in Fig. 15. One side of the transparent Form 4B cover covers the openings (69) for external cable screws and openings (70) for wire connector screws on the right side (55) of the female plug (51), while the other side of the transparent Form 4B cover covers the openings (73) for external cables, on the top cover (57) of the female plug (51) until the end of the openings (73) for external cables. Thus, the transparent Form 4B cover avoids the accidental access or contact with live parts, i.e. external cable connector holes (64), external cable connector screws (67), indicator wire connector screws, etc... Thus, the plugging assembly is intended to distribute the power to the consumer connected by the external cables whereby each internal conductor (58) in the female plug (51) passes current to external cables.

When the functional unit is inserted into its compartment, the male plug (2) fixed in the unit engages its ‘U’ shaped spring-loaded clips (4) in the male plug (2) with the internal conductors (58) in the female plug (51) where the ‘U’ shaped spring-loaded clips (4) travel through the openings (72) for the ‘U’ shaped spring-loaded clips (4) on the left side of the housing (56) of the female plug (51), engaging with the rectangular shaped longitudinal ends of the internal conductors (58) from their left side, and make power connections with female plug (51) mounted on the frame of the low-voltage switchgear. As in the first variation, a gap is maintained between the housing (6) of the male plug (2) and the left side (54) of the housing (56) of the female plug (51) where the openings (72) for ‘U’ shaped spring-loaded clips (4) are located to protect the female plug (51) being hit by the male plug (2). When the functional unit is removed from its compartment, the male plug (2) disengages its ‘U’ shaped spring-loaded clips (4) from the internal conductors (58) and withdraws from the female plug (51) disconnecting the power connections.

Thus, the above described second variation of the invention - rear access outgoing plug - makes the interconnection between the functional unit and the external cables in the low- voltage switchgear, i.e. it distributes power to the consumer by external are connected to the female plug (51). As a result, the external cable connector holes (64) and external cable connector screws (67) are accessed from the compartment behind the functional unit compartment when connecting external cables to the female plug (51). Similarly, the indicator wire connector holes (65) and their screws are also accessed.

Claims

1. A plugging assembly adapted for making electrical interconnections between the devices installed in a functional unit in a functional unit compartment, and external cables available in another compartment of a low-voltage switchgear, comprising: a. a male plug (2) to which internal wires coming from devices installed in a functional unit are connected, comprising: i. a rigid insulating housing (6) having insulating barriers (8) protruded upwards from the housing (6), a set of fixing holes (6a) and bases (7) protruded downwards from the housing (6), ii. a plurality of ‘U’ shaped spring-loaded clips (4) and iii. a plurality of terminals (5) for internal wiring; b. a female plug (3) of which ‘U’ shaped spring-loaded clips of the male plug (2) are received from the top (9), external cables and indicator wires are inserted from the right side (12) and external cables and indicator wires are connected by fastening external cable connector screws (26) and indicator wire connector screws from the top (9), comprising: i. a cuboid shaped rigid insulating housing (14) having a plurality of insulating border walls (34) with holders (17), a plurality of insulating internal ribs (16) with holders (17), a plurality of deep channels (18) with holders (17), a plurality of top cover fixing screw holes (19) and a plurality of openings (37) for external cables, ii. a plurality of internal conductors (13) having a rectangular shaped longitudinal profile at one end and at least two external cable connector holes (20) to connect two external cables, an indicator wire connector hole (21) to connect an indicator wire, at least two external cable connector screw holes (23) with external cable connector screws (26) and an indicator wire connector screw hole (24) with an indicator wire connector screw at the other end, iii. a top cover (15) having a plurality of openings (28) for ‘U’ shaped spring-loaded clips (4), a plurality of openings (29) for external cable connector screws (26), a plurality of openings (30) for indicator wire connector screws, a plurality of openings (31) for top cover fixing screws, a plurality of screw holes (32) for transparent cover fixing screws and a configuration of channels (33) at the back of the top cover (15), iv. a spring clip (38) with a notch (39) and two mounting channels (40) on the two long edges and v. an ‘L’ shaped transparent cover with cut-outs for external cables and indicator wires, of which one side covers the openings (29) for external cable screws and openings (30) for indicator wire connector screws on the top cover (15) until the end of openings (29) for external cable screws, while the other side covers the openings (37) for external cables on the right side (12) of the female plug (3); and c. a rectangular steel mounting bracket (41) having a locking hole (42), a slide stopper (43) and mounting screw holes (44).

2. A plugging assembly adapted for making electrical interconnections between the devices installed in a functional unit in a functional unit compartment, and external cables available in another compartment of a low-voltage switchgear, comprising: a. a male plug (2) to which internal wires coming from devices installed in a functional unit are connected, comprising: i. a rigid insulating housing (6) having insulating barriers (8) protruded upwards from the housing (6), a set of fixing holes (6a) and bases (7) protruded downwards from the housing (6), ii. a plurality of ‘U’ shaped spring-loaded clips (4) and iii. a plurality of terminals (5) for internal wiring; b. a female plug (51) of which ‘U’ shaped spring-loaded clips (4) of the male plug (2) are received from the left side (54), external cables and indicator wires are inserted from the top side (52) and external cables and indicator wires are connected by fastening external cable connector screws (67) and indicator wire connector screws from the right side (55), comprising: i. a cuboid shaped rigid insulating housing (56) having a plurality of insulating border walls (85) with holders (61), a plurality of insulating internal ribs (59) with holders (61), a plurality of deep channels (60) with holders (61), a plurality of top cover fixing screw holes (62), a plurality of openings (69) for external cable connector screws, a plurality of openings (70) for indicator wire connector screws, a plurality of screw holes (71) for transparent cover fixing screws and a plurality of openings (72) for ‘U’ shaped spring-loaded clips (4), ii. a plurality of internal conductors (58) having a rectangular shaped longitudinal profile at one end and at least two external cable connector holes (64) to connect two external cables, an indicator wire connector hole (65) to connect an indicator wire, at least two external cable connector screw holes (66) with external cable connector screws (67) and an indicator wire connector screw hole (68) with an indicator wire connector screw at the other end, iii. a top cover (57) having a plurality of openings (73) for external cables and a plurality of openings (74) for top cover fixing screws and a configuration of channels (75) at the back of the top cover (57), iv. a spring clip (78) with a notch (79) and two mounting channels (80) on the two long edges and v. an ‘L’ shaped transparent cover with cut-outs for external cables and indicator wires, of which one side covers the openings (69) for external cable screws and openings (70) of indicator wire connector screws on the right side (55) of the female plug (51), while the other side covers the openings in the openings (73) for external cables until the end of the openings (73) for external cables on the top cover (57) of the female plug (3); and c. a rectangular steel mounting bracket (81) having a locking hole (82), a slide stopper (83) and mounting screw holes (84),

3. The plugging assembly of Claim 1 or 2, wherein the ‘U’ shaped clips (4) in the male plug (2) are spring-loaded to expand and shrink when the clips (4) are engaged with and disengaged from a solid conductive matter.

4. The plugging assembly of Claim 1 or 2, wherein each terminal (5) is connected with at least two ‘U’ shaped spring-loaded clips (4), each having different height creating two levels of spring-loaded clips (4) for a terminal (5).

5. The plugging assembly of Claim 1 or 2, wherein the terminal (5) in the male plug (2) is connected with wires extending out from electrical devices installed in functional unit.

6. The plugging assembly of Claim 1 or 2, wherein each terminal (5) and ‘U’ shaped spring-loaded clips (4) connected to each terminal in the male plug (2) is dedicated to the three phases and the neutral in the power supply.

7. The plugging assembly of Claim 1 or 2, wherein the housing (6) of the male plug (2) is moulded to have insulating barriers (8) protruded upwards from the housing, covering the terminals (5) from three sides and to have the bases (7) of the ‘U’ shaped spring- loaded clips protruded downwards from the housing with inwardly tapered tops (47).

8. The plugging assembly of Claim 1 or 2, wherein the insulating border walls (34 or 85) with holders (17 or 61) and insulating internal ribs (16 or 59) with holders (17 or 61) create deep channels (18 or 60) and separate internal conductors (13 or 58) in the housing of the female plug.

9. The plugging assembly of Claim 1 or 2 and 8, wherein the deep channels (18 or 60) with holders (17 or 61) in the housing (14 or 56) of the female plug, guide and accommodate the internal conductors (13 or 58) and hold the internal conductors (13 or 58) vertically and firmly with the holders (17 or 61) in the deep channels (18 or 60).

10. The plugging assembly of Claim 1, wherein three of the insulating border walls (34) have a step (36) on the outside of and at the top edges of the three boarder walls (34).

11. The plugging assembly of Claim 1 or 2, wherein the spring clip (38 or 78) is positioned in the bottom of the housing (14 or 56) along the center line of the width of the housing of the female plug.

12. The plugging assembly of Claim 1 or 2, wherein the internal conductor (13 or 58) accommodated in the housing (14 or 56) of the female plug is a single solid block of conductive material which runs from the left side (11 or 54) to the right side (12 or 55) of the female plug.

13. The plugging assembly of Claim 1 or 2, wherein the two external cable connector holes (20 or 64) are located on top of each other, or next to each other, in the internal conductor (13 or 58) in the housing (14 or 56) of the female plug and have different depths, where the depth of one external cable connector hole is greater than the depth of the other external cable connector hole.

14. The plugging assembly of Claim 1 or 2, wherein the two external cable connector holes (20 or 64) and the indicator wire connector hole (21 or 65) are located on the same surface of the cable connector end of the internal conductor (13 or 58) in the housing (14 or 56) of the female plug (3 or 51).

15. The plugging assembly of Claim 1 or 2, wherein the two external cable connector screw holes (23 or 66) and the indicator wire connector screw hole (24 or 68) are located on the same surface of the cable connector end of the internal conductor (13 or 58) in the housing (14 or 56) of the female plug (3 or 51).

16. The plugging assembly of Claim 1 or 2, wherein the two external cable connector screw holes (23 or 66) are located in line next to each other, have different depths and are sunk into their respective external cable connector holes (20 or 64) in the internal conductor (13 or 58) in the housing of the female plug.

17. The plugging assembly of Claim 1 or 2 and 16, wherein the external cable connector screw hole (23 or 66) which sinks into the deeper external cable connector hole (20 or 64), has a counterbore in the top or first section of the external cable connector screw hole, so that the external cable connector screw (26 or 67) is not driven from the top of the hole in the internal conductor (13 or 58).

18. The plugging assembly of Claim 1 or 2, wherein the two external cable connector screws (26 or 67) in the two external cable connector screw holes (23 or 66) in the internal conductor have the same thread height and are riveted with a clamp (27 or 86) at the thread end.

19. The plugging assembly of Claim 2, wherein the two external cable connector screw holes (66) and their respective external cable connector holes (64) are located inside the internal conductor (58) in an angular manner with respect to bottom (53) of the housing (56), maintaining a right angle between the two center axes of the external cable connector screw holes (66) and external cable connector holes (64).

20. The plugging assembly of Claim 1 or 2, wherein each internal conductor (13 or 58) in the female plug is dedicated to the three phases and the neutral in the power supply.

21. The plugging assembly of Claim 1, wherein the openings (28) for ‘U’ shaped spring- loaded clips (4) on the top cover (15) are shaped into thin rectangular with rounded corners with a tapered bottom resembling the shape of the base (7) of ‘U’ shaped spring- loaded clip (4) and are sized slightly greater than the size of the base (7) of the ‘U’ shaped spring-loaded clip (4).

22. The plugging assembly of Claim 2, wherein the openings (72) for ‘U’ shaped spring- loaded clips (4) on the left side of the housing (56) are shaped into thin rectangular with rounded corners with a tapered bottom resembling the shape of the base (7) of ‘U’ shaped spring-loaded clip (4) and are sized slightly greater than the size of the base (7) of the ‘U’ shaped spring-loaded clip (4).

23. The plugging assembly of Claim 1, wherein the openings (37) for external cables are located on the right side of the housing (14) of the female plug (3).

24. The plugging assembly of Claim 2, wherein the openings (73) for external cables and openings (74) for top cover fixing screws are located on the top cover (57) of the female plug (51).

25. The plugging assembly of Claim 1, wherein the configuration of channels (33) at the back of the top cover (15) are designed to be sunk into the top edges of the internal ribs (16) and that of the three border walls (34) in the housing (14) of the female plug (3), until the bottom of edges (35) of the top cover (15) hit the step (36) on the border wall (34) of the housing (14), when the top cover (15) is placed on the top of the housing (14).

26. The plugging assembly of Claim 2, wherein the configuration of channels (75) at the back of the top cover (57) is designed to be sunk into the top edges of the internal ribs (59) and the bottom edges (76) of the top cover (57) stops on the housing (56) of the female plug (51) when the top cover (57) is placed on the top of the housing (56).

27. The plugging assembly of Claim 2, wherein the back of the top cover (57) has a set of slots (77) which accommodate the top edges of the internal conductors (58) when the top cover (57) is placed on the housing (56).

28. The plugging assembly of Claim 1 or 2, wherein the top cover (15 and 57) is fixed to the housing (14 and 56) with screws driven through openings (31 or 74) into top cover fixing screw holes (19 and 62) on the border walls (34 or 85) of the housing (14 or 56) of the female plug.

29. The plugging assembly of Claim 1 or 2, wherein the long edges of the rectangular steel mounting bracket (41 or 81) are formed as flanged edges to allow sliding -in mounting channels (40 or 80) on the bottom of the housing (14 or 56) of female plug.

30. The plugging assembly of Claim 1 or 2, wherein the female plug (3 or 51) is mounted to the bracket (41 or 81) by inserting and sliding -in the mounting channels (40 or 80) on the bottom of the housing (14 or 56) of the female plug along the flanged edges of the bracket (41 or 81) until the notch (39 or 79) reaches the locking hole (42 or 82) on the bracket and locks making a “click” sound.

31. The plugging assembly of Claim 1 or 2, wherein the female plug (3 or 51) is un mounted from the bracket (41 or 81) by pressing the free end (46) of the spring clip (38 or 78) while sliding-out the female plug from the bracket (41 or 81).

32. The plugging assembly of Claim 1 or 2, wherein the ‘L’ shaped transparent cover with cut-outs for external cables and indicator wires, is fixed using a set of screws driven into transparent cover fixing screw holes (32 or 71) on the female plug, of which one side covers the openings (29 or 69) for external cable screws and openings (30 or 70) indicator wire connector screws in the female plug, while the other side covers rest of the openings in the openings (37 or 73) for external cables.

33. The plugging assembly of Claim 1 or 2 is adapted for supplying power to the load connected to the external cables whereby each internal conductor (13 or 58) in the female plug (3 or 51) passes current to at least one external cables.

34. The plugging assembly of Claim 1 or 2, wherein an external cable is connected to the female plug (3 or 51) by inserting the external cable into external cable connector hole (20 or 64) and fastening the external cable connector screw (26 or 67) in the external cable connector screw hole (23 or 66) in the internal conductor (13 or 58).

35. The plugging assembly of Claim 1 or 2, wherein an indicator wire is connected to the female plug (3 or 51) by inserting an indicator wire into indicator wire connector hole (21 or 65) and fastening the indicator wire connector screw in the indictor wire connector screw hole (24 or 68) in the internal conductor (13 or 58).

36. The plugging assembly of Claim 1 or 2, wherein an indicator of each phase on front panel of low-voltage switchgear is wired by connecting two wires with the internal conductor (13 or 58) representing the neutral and the internal conductor (13 or 58) representing a phase in the female plug (3 or 51).

37. The plugging assembly of Claim 1 or 2, wherein the female plug (3 or 51) is mounted horizontally on to a frame member of a low-voltage switchgear, keeping the openings (28 or 72) for the ‘U’ shaped spring-loaded clips (4) in the functional compartment and facing towards the front side of the low-voltage switchgear while the openings (37 or 73) for external cables in an adjacent cable compartment on the left, right or back of the functional compartment of a low-voltage switchgear.

38. The plugging assembly of Claim 1 or 2 and 37, wherein the female plug (3 or 51) is mounted horizontally on to a frame member of a low-voltage switchgear, keeping the openings (28 or 72) for the ‘U’ shaped spring-loaded clips (4) in the functional compartment and the openings (37 or 73) for external cables in the adjacent cable compartment on the left, right or back of the functional compartment such that the external cable connector holes (20 or 64), indicator wire connector holes (21 or 65), external cable connector screws (26 or 67) and indicator wire connector screws are accessed from the said cable compartment when connecting external cables to the female plug (3 or 51).

39. The plugging assembly of Claim 1, wherein the male plug (2) is connected with the female plug (3) by inserting the ‘U’ shaped spring-loaded clips (4) in the male plug (2) through the openings (28) for the ‘U’ shaped spring-loaded clips on the top cover (15) of the female plug (3) and engaging with the rectangular shaped longitudinal ends of the internal conductors (13) from their top, while maintaining a gap between the housing (6) of the male plug (2) and the front surface of the top cover (15) of the female plug (3) to protect the female plug (3) being hit by the male plug (2).

40. The plugging assembly of Claim 2, wherein the male plug (2) is connected with the female plug (51) by inserting the ‘U’ shaped spring-loaded clips (4) in the male plug (2) through the openings (72) for the ‘U’ shaped spring-loaded clips (4), on the left side of the housing (56) of the female plug (51) and engaging with the rectangular shaped longitudinal ends of the internal conductors (58) from their left side, while maintaining a gap between the housing (6) of the male plug (2) and the left side (54) of the housing (56) of the female plug (51) where the openings (72) for ‘U’ shaped spring-loaded clips (4) are located, to protect the female plug (51) being hit by the male plug (2).

41. A method for making and removing electrical interconnections between the devices installed in a functional unit in a functional unit compartment, and external cables available in another compartment of a low-voltage switchgear, as claimed in Claims 1 or 2, such method comprising steps of: a. Fixing male plug (2) in a functional unit of a low-voltage switchgear, using fixing holes (6a), in a manner which extends out the ‘U’ shaped spring-loaded clips (4) towards rear side of the functional unit allowing the spring-loaded clips (4) to be mechanically inserted into the female plug (3 or 51) when the unit is fully pushed into its compartment in the low-voltage switchgear; b. Wiring the terminals (5) of the male plug (2) internally with the devices installed inside the functional unit; c. Fixing the rectangular steel mounting bracket (41 or 81), having locking hole (42 or 82) and slide stopper (43 or 83), using mounting screw holes (44 or 84), horizontally on to a frame member of the low-voltage switchgear in the functional unit compartment enabling the female plug (3 or 51) to be mounted in a manner facing its openings (28 or 72) for ‘U’ shaped spring-loaded clips (4) towards the front side of the low-voltage switchgear and openings (37 or73) for external cables extending out to a compartment located on the left, right or back of the said functional unit compartment; d. Mounting the female plug (3 or 51) by inserting and sliding-in its mounting channels (40 or 80) on the bottom of the housing (14 or 56) of female plug (3 or 51) along the flanged edges of the bracket (41 or 81) until the notch (39 or 79) reaches the locking hole (42 or 82) on the bracket and locks making a “click” sound, while one end of the spring clip (38 or 78) on the bottom hits the slide stopper (43 or 83) in the bracket (41 or 81); e. Fixing external cables to female plug (3 or 51) by inserting external cables into external cable connector holes (20 or 64) and fastening the external cable connector screws (26 or 67) in external cable connector screw holes (23 or 66); f. Fixing indicator wires to female plug (3 or 51) by inserting indicator wires into indicator wire connector holes (21 or 65) and fastening the indicator wire connector screws in indicator wire connector screw holes (24 or 68); g. Fixing transparent cover with cut-outs for external cables and indicator wires using a set of screws driven into transparent cover fixing screw holes (32 or 71). h. Fully inserting the functional unit into its compartment enabling the ‘U’ shaped spring-loaded clips (4) to be engaged with the internal conductors (13 or 58) in the female plug to make the electrical interconnections; and i. Removing the functional unit from its compartment enabling the ‘U’ shaped spring-loaded clips (4) to be disengaged with the internal conductors (13 or 58) in the female plug (3 or 51) to remove the electrical interconnections.