EP2875551B1

EP2875551B1 - Assembly comprising a plugging-in unit, a receiving base unit and a steel rectangular mounting bracket

Info

Publication number: EP2875551B1
Application number: EP13753206.5A
Authority: EP
Inventors: Erik Logstrup
Original assignee: Elsteel Danmark AS
Current assignee: Elsteel Danmark AS
Priority date: 2012-07-23
Filing date: 2013-07-23
Publication date: 2017-08-30
Anticipated expiration: 2033-07-23
Also published as: WO2014016662A1; AU2013294729A1; AU2013294729B2; DK2875551T3; PL2875551T3; IN2015DN00508A; EP2875551A1

Description

TECHNICAL FIELD

The present invention relates to the field of electrical power distribution and control centers or motor control centers, particularly with regard to plug-in connections used therein to connect control devices in withdrawable units to output cables. In particular, the present invention relates to a plugging assembly that is adapted to bridge the connections extending out from a withdrawable unit inserted in one compartment, directly with the cables laid-out in another adjoining compartment of an electrical power distribution and control system or such similar system. It also relates to a corresponding method for bridging and integrating power, control and data connections for a withdrawable unit using the plugging assembly.

BACKGROUND ART

Generally, the electrical power distribution and control systems, switchgear assemblies or motor control centers are compartmentalized into compartments depending on the devices and components which they are equipped with and the purpose for which they are used. For instance, the compartment in which busbars are fixed is commonly known as busbar compartment whereas the compartment where cables are laid out is commonly known as cable compartment. The device compartment houses the control devices and components such as circuit-breakers, switches, relays, etc ... which are either fixed in to the device compartment itself or fixed on to drawers-like withdrawable units inserted into device compartment. The devices and components in the withdrawable units are internally wired to a set of terminals/contact pins extending out from the rear wall of the withdrawable unit. When a withdrawable unit is inserted into its device compartment, the said contact pins plug-in to a plug-base or receptacle base suitably positioned in the housing structure and thereby make the connection between the devices in the withdrawable unit and the plug-base. In conventional electrical power distribution and control systems or any other such systems the plug-base is connected with the out-going cables in the cable compartment using another set of busbars or similar kind of conductors. These conductors follow a long path often from busbar compartment to cable compartment to establish the connections with out-going cables. There can be more than one such connection types such as power, control/auxiliary, data/signal, etc .... where each connection type requires at least one dedicated inter-mediate conductor.
Though the prior art discloses plug-in technologies that can be adapted for withdrawable units, none of them has not been able to integrate all connection types in a single plugging assembly and to avoid use of the intermediate set of conductors.

DISCLOSURE OF THE INVENTION

As a whole, the invention is a "L" shaped assembly as defined in appended claim 1 comprising two mating components namely plugging-in unit and receiving base unit which bridges the connections between the control devices installed in a withdrawable unit housed in a device compartment and the out-going cables in the cable compartment of an electrical power distribution and control center or motor control center. The invention employs a plug-in mechanism to make power, control and data connections whereby the plugging-in unit fixed in the withdrawable unit plugs-in to the receiving base unit mounted on a frame member in the same device compartment of such an electrical power distribution and control center. The main purpose of this invention is to provide a compact assembly which offers multiple types of connections such as power, control and data connections integrated in to a single assemble and diverted to the cable compartment directly to reach out-going cables immediately. The 'L' shape of the assembly enables to divert the connections from device compartment to the adjoining cable compartment directly, without using a set of intermediate conductors between the receiving base unit and the corresponding out-going cables.
Thus, the invention provides a practical solution to reduce the use of intermediary conductors between the plug-base in one compartment and the out-going cables in another compartment and the use of separate conductors for each connection type. The invention also relates to a method for bridging and integrating power, control and data connections as defined in the appended method claim 16.
As far as the advantages over the existing technology is considered, since the invention integrates all connection in one assembly and eliminates the use of intermediary conductors, it offers mainly two fold advantages; it saves significant amount of space in device, busbar and cable compartments and reduces material cost on intermediary conductors which in turn brings down the manufacturing cost of electrical power distribution and control systems. Due to the step-wise design molded in to the plugging-in unit and the receiving base unit, fixing cables can be done conveniently and in an orderly manner where in-coming cables and their corresponding out-going cables are easily indentified. Thus, it increases the user friendliness in in-coming and out-going cabling in the electrical power distribution and control systems manufacturing DE-10 2010 022 987 A1 is considered as the closest prior art and discloses a plugging assembly for bridging connections of power and data having a plugging-in unit and a receiving base unit for power and control transmission through cables.

BRIEF DESCRIPTION OF DRAWINGS

An exemplary embodiment of the invention is shown in the following figures (Fig. 1 - 12).

Fig. 1 is an isometric exploded view of the complete invention (Power & Control Plug).
Fig. 2 is a side view of the plugging-in unit of the invention showing the conceptual break-down of the plugging-in unit.
Fig. 3 is an isometric view of the plugging-in unit of the invention.
Fig. 4 is a front view of the plugging-in unit of the invention.
Fig. 5 is a top view of the plugging-in unit of the invention.
Fig. 6 is an isometric exploded view of the plugging-in unit with the D-Subminiature type male connector of the invention.
Fig. 7 is a rear view of the plugging-in unit of the invention (without the D-Subminiature type male connector).
Fig. 8 is an isometric view showing the conceptual break-down and step-wise design in the receiving base unit of the invention.
Fig. 9 is a top view of the receiving base unit of the invention.
Fig. 10 is a right side view of the receiving base unit of the invention.
Fig. 11 is an illustration of mounting mechanism of the receiving base unit of the invention.
Fig. 12 is an isometric view of the receiving base unit with its polycarbonate cover and the mounting bracket.

DETAILED DESCRIPTION OF THE INVENTION

The invention is a compact out-going plug that integrates multiple connections, namely power, control and data connections in a single assembly having an innovative 'L' shape, when its main components, i.e. plugging-in unit (10) and receiving base unit (60), are plugged in together. This innovative 'L' shape makes available the connections in withdrawable unit directly from device compartment to cable compartment through the assembly itself in the shortest possible path to reach out-going cables. In other words, the invention avoids the usage of a set of conductors like busbars or cables that is conventionally used in electrical power distribution and control centers, to connect out-going plug terminals in the device compartment with their corresponding out-going cables in the cable compartment.
As shown in Fig.1, the invention consists of three main components, namely plugging-in unit (10) which is the male component, the receiving base unit (60) which is the female component of the assembly and the mounting bracket (93) of the receiving base unit (60).
Basically, the plugging-in unit (10) comprises a non-conductive rigid housing (11) that accommodates in-coming cable insertion holes (21 & 25), in-coming cable terminals (22 & 26), in-coming cable terminal screw holes (23 & 27), in-coming cable terminal screws (24 & 28), connector pins (41 & 42), two guide pins (43) and a D-subminiature type male connector (30).
Reference to Fig. 2, the plugging-in unit (10) of the invention is conceptually broken-down into three sections as front side (20), middle section (12) and rear side (40) for describing purposes; the middle section (12) of the plugging-in unit (10) is a rectangular base (13); the left and the right sides of the rectangular base (13) are referred to as the front side (20) and the rear side (40) of the plugging-in unit (10), respectively.
As shown in Fig. 2, the front side (20) of the plugging-in unit (10) is developed to have a step-wise design to accommodate and fix more in-coming cable connections and to increase the user friendliness in terms of distinguishing connection types and fixing in-coming cables in an orderly manner. Each step is a series of in-coming cable insertion holes of (21 or 25) and a series of in-coming cable terminal screw holes of (23 or 27), each located right perpendicular to the other.
As shown in Figs. 3, 4 & 5, the solid connector pins (41 & 42) run internally through the rectangular base (13) from rear side (40) and reach in-coming cable insertion holes (21 & 25) in the front side (20) providing in-coming cable terminals (22 & 26) which are surrounded by and located inside the in-coming cable insertion holes (21 & 25). Thus, one end of each connector pin (41) or (42) is formed as an in-coming cable terminal (22 or 26) comprising a terminal hole for receiving an in-coming cable and a threaded screw hole placed closer to edge and on the body of the connector pin (41 or 42) to receive a terminal screw of (24 or 28). The terminal screws (24 or 28) meant for tightening the incoming cables, are inserted through terminal screw holes (23 or 27) and partly tighten to fix the connector pins (41 or 42) in to the plugging-in unit (10), whereby the terminal screws (23 & 27) have a dual functionality.
The front side (20) of the plugging-in unit (10) receives in-coming power and control cables from devices installed in the withdrawable unit and are connected to the plugging-in unit (10) by inserting them into in-coming power and control cable insertion holes (21 & 25) to reach in-coming power and control cable terminals (22 & 26) and are tightened with their respective terminal screws (24 & 28).
Furthermore, reference to Figs. 6 & 7, the front side (20) of the plugging-in unit (10) provides with a rectangular channel (29) for a D-subminiature type male connector (30) which connects the data connections receiving from devices in the withdrawable unit. This D-subminiature type male connector (30) is structurally modified to facilitate its fixing, plugging-in and plugging-out mechanisms; the male connector of a generic D-subminiature type connector is placed inside a housing (31) having a rectangular longitudinal profile which enables the generic connector to have a body long enough to be slide in its rectangular channel (29) during plugging-in and plugging-out operations. Unlike the in-coming power and control cable connections, one end of the data connection cable is pre-wired to the D-subminiature type male connector (30); the other end meant to be connected to the devices in the withdrawable unit is passed through the rear aperture (44) of the rectangular channel (29) on the rear side (40) of the plugging-in unit (10) and is taken out from that of the front aperture (32) to extend towards the devices. Two springs are inserted into the side channels (45) in the left and right side walls of the rectangular channel (29); the D-subminiature type male connector (30) is then force-inserted through rear aperture (44) and is held in its rectangular channel (29) by the holding screw (46) inserted through the sliding slot (33) on the outer wall (34) of the rectangular channel (29), and is fixed to threaded screw hole (35) on the D-subminiature type male connector (30) itself. Thus, the male connector (30) becomes spring-loaded and moveable backward and forward inside the rectangular channel (29) during the plugging-in and plugging-out operations. The sliding slot (33) limits the forward and backward movement of the D-subminiature type male connector (30) so that the D-subminiature type male connector (30) is retained in its channel (29).
As shown in Fig. 3, the rear side (40) of the plugging-in unit (10) is configured with a series of connector pins (41 & 42) in parallel rows, two guide pins (43) and the head (47) of the D-Subminiature type connector (30), each having different lengths from the rectangular base (13), to engage and disengage the connections at different points of time during the plugging-in and plugging-out operations. The two guide pins (43), located closer to one longer edge of the rectangular base (13), are the longest pins in the pin configuration of the rear side (40) of the plugging-in unit (10). The next longest set of connector pins are control connector pins (42) that deals with the control connections. The control connector pins (42) are in two rows having a slight length difference between the two rows. The power connector pins (41) which pass the power connections are the shortest set of pins in the rear side (40) of the plugging-in unit (10).
During the plugging-in and plugging-out operations, the configuration of pins on the rear side (40) of the plugging-in unit (10) enables guide pins (43) to be inserted in to corresponding guide pin holes (75 in Fig. 8) prior to all the other connector pins (41 & 42) and to be released from relevant plug holes (75 in Fig. 8) at last; thereby, the two guide pins (43) guarantee the secure insertion and release of all power and control connector pins (41 & 42) to and from their corresponding plug-holes (71 & 73 of Fig. 8). Furthermore, during the plugging-in and plugging-out operations the connector pin configuration allows the power connector pins (41) to be engaged at last and to be disengaged first while the control connector pins (42) and D-Subminiature type male data connector (30) are still connected in both operations. As result of this status, the testing of control connections can be performed without any hazardous risks from power connections. The control connector pins (42) and the spring loaded D-subminiature type male connector (30) are engaged first and disengaged last when inserting and removing the withdrawable unit.
The plugging-in unit (10) is fixed inside a withdrawable unit by using the self-threading mounting holes (14) on the rectangular base (13), exposing the front side (20) into the withdrawable unit and extending its rear side (40) outward from the rear wall of the withdrawable unit.
Reference to Fig. 8, the receiving base unit (60) is conceptually broken-down into two sections as front side (70) and right side (80) for describing purposes.
The receiving base unit (60) of the invention is a non-conductive rigid housing that accommodates mainly plug holes (71 & 73), plug hole terminals (72 & 74), two guide pin holes (75), out-going cable insertion holes (81 & 85), out-going cable terminal holes (82 & 86), terminal screws holes (83 & 87), terminal screws (84 & 88) and a D-Subminiature type female connector (76).
As shown in Fig. 8, the front side of the receiving base unit (60) is configured to have series of plug holes (71 & 73) in parallel rows and two guide pin holes (75). They are precisely positioned to receive the in-coming connector pins (41 & 42) and the two in-coming guide pins (43). The power connector pins (41), the control connector pins (42) and the two guide pins (43) in the plugging-in unit are received by the power connector plug holes (71), control connector plug holes (72) and the guide pin holes (75) in the receiving base unit (60), respectively.
Reference to Fig. 8, 9 & 10, the power and control connector plug holes (71 & 73) accommodate power and control connector terminals (72 & 74) which contact with the in-coming connector pins (41 & 42) of the plugging-in unit (10). The receiving base unit (60) houses a set of 'L' shaped solid conductors which run internally from the power and control connector plug holes (71 & 73) on the front side (70) through the solid housing (61) up to out-going power and control cable insertion holes (81 & 85) in the right side (80) of the receiving base unit (60). The 'L' shaped conductor end that terminates in the connector plug hole (71 or 73) is formed as a connector terminal of (72 or 74) to receive the in-coming connector pins (41 or 42) whereas its other end that terminates in the out-going cable insertion hole (81 or 85) is formed as an out-going cable terminal of (82 or 86) which comprises a terminal hole to receive out-going power or control cable and a threaded screw hole placed closer to edge and on the body of the conductor to receive out-going cable terminal screw (84 or 88) meant for tightening the out-going cables. The out-going power and control cables are inserted through out-going cable insertion holes (81) & (85) and are fastened to their out-going cable terminals (82 & 86) by out-going cable terminal screws (84) & (88) inserted through out-going cable terminal screw holes (83 & 87).
As shown in Fig. 8, the right side (80) of the receiving base unit (60) is also developed to have a step-wise design to accommodate and fix more out-going cable connections and to increase the user friendliness in terms of distinguishing connection types and fixing out-going cables in an orderly manner. Each step is a series of out-going cable insertion holes (81 or 85) and a series of out-going cable terminal screw holes (83 or 87) each located right perpendicular to the other.
Furthermore, reference to Figs. 8 & 9, the D-Subminiature type female connector (76) is accommodated in an 'L' shaped slot provided in the solid housing (61) and is fixed with two screws (77) facing the front side (70) to receive the in-coming D-Subminiature type male connector (30) in the rear side (40) of the plugging-in unit (10). Before fixing the D-Subminiature type female connector (76), one end of the data cable is pre-wired with the female connector (76) and the other end meant to be connected to operating devices is passed through the front aperture (78) and is taken out from the right side aperture (79) of the 'L' shaped slot.
As shown in Fig. 11, the rear surface (90) of the housing (61) of the receiving base unit (60) is molded to have two longitudinal mounting channels (92) along the longer edges of the rear surface (90) and a spring clip (91) with a notch (99). The spring clip (91) is positioned along the center line of the width, and its clipping edge (102) is aligned to the right edge (98) of the rear surface (90).
Further to Fig. 11, the rectangular steel mounting bracket (93) comprises a lock hole (96), a slide stopper (97) and mounting screw holes (95). Its longitudinal edges are formed as flanged edges (94) to allow sliding-in mounting channels (92) on the rear surface (90) of the housing (61). The mounting bracket (93) is fixed to a frame member in the device compartment of the electrical power distribution and control system. The receiving base unit (60) is fixed to the mounting bracket (93) by inserting its two mounting channels (92) in to the two flanged edges (94) of the mounting bracket (93) and sliding-in the receiving base unit (60) until the notch (99) on the spring clip (91) automatically snaps in to the lock hole (96) making a "click" sound; at the same time, the fixed edge (101) of the spring clip (91) reach to the slide stopper (97) and stops further sliding-in. The receiving base unit (60) can be un-mounted from the bracket (93) by pressing the clipping edge (102) of the spring clip (91) while sliding-out the unit (60).
As shown in Fig. 12, a polycarbonate cover (89) is fixed on to the right side (80) of the receiving base unit (60) using two screws inserted through the cover screw holes (103) on the polycarbonate cover (89) and fastening into the two self-threaded screw holes (104). The out-going cables are taken out through the cut-outs (100) on the polycarbonate cover (89).

Claims

A 'L' shape plugging assembly, that is adapted to bridge the connections extending out from a withdrawable unit inserted in one compartment, directly with the cables laid-out in another adjoining compartment of an electrical power distribution and control system or such similar system, without using any external intermediary conductors, comprising:
a. a plugging-in unit (10) having a non-conductive rigid housing (11) with a rectangular base (13) in the middle, that accommodates a plurality of in-coming power cable insertion holes (21), in-coming power cable terminals (22), in-coming power cable terminal screw holes (23), in-coming power cable terminal screws (24), in-coming control cable insertion holes (25), in-coming control cable terminal (26), in-coming control cable terminal screw holes (27) and in-coming control cable terminal screws (28) to receive in-coming connections; a D-subminiature type male connector (30), a plurality of power connector pins (41), and control connector pins (42) to engage in and to pass such incoming connections to a receiving base unit (60) and at least two guide pins (43) on its rear side (40) and self-threading mounting holes (14) on the said rectangular base (13);

b. the receiving base unit (60) having non-conductive rigid housing (61) that accommodates a plurality of power connector plug holes (71), power connector terminals (72), control connector plug holes (73), control connector terminals (74) and a D-Subminiature type female connector (76) to receive such connections; at least two guide pin holes (75) on its front side (70); a plurality of out-going power cable insertion holes (81), out-going power cable terminals (82), out-going power cable terminal screw holes (83), out-going power cable terminal screws (84), out-going control cable insertion holes (85), out-going control cable terminals (86), out-going control cable terminal screw holes (87), out-going control cable terminal screws (88) to pass such connections to out-going cables and a polycarbonate cover (89) in its right side (80); a spring clip (91) and two mounting channels (92) on its rear side (90) and

c. a steel rectangular mounting bracket (93), with flanged longitudinal edges (94), having screw holes (95), a lock hole (96) and a slide stopper (97) on its front rectangular surface.
In accordance with claim 1, the 'L' shape plugging assembly characterized in with the plugging-in unit (10) of which the front side (20) is molded to have a step-wise configuration where each step is a series of in-coming cable insertion holes (21 or 25) and a series of terminal screw holes (23 or 27), each series of holes located right perpendicular to the other.
In accordance with claim 1, the 'L' shape plugging assembly characterized in that the plugging-in unit (10) houses solid connector pins (41 & 42), running internally through its rectangular base (13) from rear side (40) to front side (20), of which the ends terminating in in-coming cable insertion holes (21 or 25) are formed as incoming cable terminals (22 or 26) having a hole to engage with an in-coming cable and a threaded screw hole which receives the in-coming cable terminal screw (24 or 28) through in-coming terminal screw hole (23 or 27) to fix the said connector pins (41 or 42) to the plugging-in unit (10).
In accordance with claims 1 & 3, the 'L' shape plugging assembly characterized in that the in-coming cable terminal screw (24 or 28) in the plugging-in unit (10), inserted through in-coming cable terminal screw hole (23 or 27) has a dual function of holding the connector pin (41 or 42) to the housing (11) of the plugging-in unit (10) and connecting in-coming cable into the in-coming cable terminal (22 or 26).
In accordance with claim 1, the 'L' shape plugging assembly is characterized in that the plugging-in unit (10) that provides with a rectangular channel (29) having two side channels (45), each having a spring inserted, in the left and right side walls and a sliding slot (33) on the outer wall of the said rectangular channel (29).
A 'L' shape plugging assembly in accordance with claims 1 & 5, the D-subminiature type male connector (30), having a housing (31) with a rectangular longitudinal profile, is spring loaded to slide forward and backward inside the rectangular channel (29) during the plug-in and plug-out operations and is retained in the rectangular channel (29) by the holding screw (46) fixed on to the said housing (31) through the sliding slot (33).
In accordance with claims 1 & 3, the 'L' shape plugging assembly characterized in that the plugging-in unit (10) having a configuration of connector pins (41 & 42) and guide pins (43) with varying lengths such that the guide pins (43), control connector pins (42) and power connector pins (41) are in the decreasing order of the lengths which define the engaging and disengaging timing of the said pins (43, 42 & 41) with their corresponding connector plug holes (75, 73 & 71) in the receiving base unit (60).
In accordance with claim 1, the 'L' shape plugging assembly is characterized in that the receiving base unit (60) having power and control connector plug holes (71 & 73) accommodating power and control connector terminals (72 & 74) formed to be engaged with the in-coming connector pins (41 & 42) of the plugging-in unit (10) and at least two guide pin holes (75) to receive guide pins (43) in the plugging-in unit.
In accordance with claim 1, the 'L' shape plugging assembly characterized in that the receiving base unit (60) houses a set of 'L' shaped solid conductors running internally from the power and control connector plug holes (71 & 73) on the front side (70) through the solid housing (61) up to out-going power and control cable insertion holes (81 & 85) in the right side (80) of the receiving base unit (60).
In accordance with claims 1 & 9, the 'L' shape plugging assembly characterized in that the 'L' shaped conductor ends terminating in the connector plug holes (71 or 73) are formed as connector terminals of (72 or 74) to engage with the in-coming connector pins (41 or 42) and that of other ends terminating in the out-going cable insertion holes (81 or 85) are formed as an out-going cable terminals of (82 or 86) cach comprising a terminal hole to receive out-going power or control cables and a threaded screw hole placed closer to edge and on the body of the conductor to receive out-going cable terminal screw (84 or 88), meant for connecting out-going cables to the said terminals (82 or 86), inserted through out-going cable terminal screw holes (83 or 87).
In accordance with claim 1, the 'L' shape plugging assembly characterized in that the receiving base unit (60) of which the right side (80) is molded to have a step-wise configuration where each step is a series of out-going cable insertion holes (81 or 85) and a series of terminal screw holes (83 or 87), each located right perpendicular to the other.
In accordance with claim 1, the 'L' shape plugging assembly characterized in that the receiving base unit (60) accommodates a D-Subminiature type female connector (76) in an 'L' shaped slot by fixing it with two screws (77) facing the front side (70) to receive the in-coming D-Subminiature type male connector (30) in the rear side (40) of the plugging-in unit (10).
In accordance with claim 1, the 'L' shape plugging assembly characterized in that the rear surface of the receiving base unit (60) is molded to have two longitudinal mounting channels (92) along the longer edges of the rear surface (90) and a spring clip (91) with a notch (99) such that the spring clip (91) is positioned along the center line of the width, having its clipping edge (102) aligned to the right edge (98) of the rear surface (90).
A 'L' shape plugging assembly in accordance with claim 1, the rectangular steel mounting bracket (93), being adapted to be fixed to a frame member in the device compartment of an electrical distribution and control system, and comprising a lock hole (96), a slide stopper (97), mounting screw holes (95) and flanged longitudinal edges (94).
In accordance with claims 1, the 'L' shape plugging assembly characterized in that the right side (80) of the receiving base unit (60) is covered by a polycarbonate cover having cut-outs (100) and the said polycarbonate cover is fixed on to the receiving base unit (60) with two screws inserted through the cover screw holes (103) and fastened into the two self-threaded screw holes (104).
A method for bridging and integrating power, control and data connections coming out from the devices or components installed in a withdrawable unit, with their destined out-going cables laid-out in the adjoining cable compartment directly, without using any other external conductors, such method comprising the steps of
a. Fixing the plugging-in unit (10) inside the withdrawable unit using the self-threading mounting holes (14) on the rectangular base (13), exposing its front side (20) into the withdrawable unit and extending its rear side (40) outward from the rear wall of the withdrawable unit;

b. Connecting in-coming power and control cables to in-coming cable terminals (22 & 26) in the plugging-in unit (10) using in-coming cable terminal screws (24 & 28) and the pre-wired D-Subminiature type male connector (30) cable end to the devices or components in the withdrawable unit;

c. Fixing the rectangular steel mounting bracket (93) to a frame member in the device compartment of the electrical power distribution and control system;

d. Sliding-in the receiving base unit (60) into the mounting bracket (93);

e. Connecting out-going power and control cables to out-going cables terminals (82 & 86) in the receiving base unit (60) using out-going cable terminal screws (84 & 88) and the pre-wired D-Subminiature type female connector (76) cable end to an out-going data connector and

f. Mounting the polycarbonate cover (89) on to the right side (80) of the receiving base unit (60) using two screws inserted through the cover screw holes (103) on the polycarbonate cover (89) and fastening into the two self-threaded screw holes (104).
The method of claim 16 wherein the sliding-in the receiving base unit further includes that the mounting channels (92) on the rear surface (90) of the receiving base unit (60) are slide-in through the flanged edges (94) of the mounting bracket (93) until the notch (99) on the spring clip (91) automatically snaps in to the lock hole (96) making a "click" sound while the fixed edge (101) of the spring clip (91) reach to the slide stopper (97) and stops further sliding-in.