FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Switchgear Device"
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: LARSEN & TOUBRO LIMITED,
L&T House, Ballard Estate, P. 0. Box: 278, Mumbai 400 001, India
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Switchgear Device Field of the invention
The present invention relates to a switchgear device, and more particularly, to housing for a single pole switchgear device.
Background of the invention
A modular device is used in distribution and building segments for isolating, protecting and controlling the equipments. The modular devices include a housing which is the main part of all devices. In general all modular devices consist of two parts one is the housing and another is a cover. However there are drawbacks of using two separate parts.
The limitation with different housing and cover are as follows:
a. Two different plastic molds are required to mold the housing and cover, with
this the mold cost increases and hence productivity reduces.
b. With two different cassettes, it is very difficult to commonize internal
components like terminals, source separator and the like resulting in an increase
in number of plastic molds as well as press tool and overall cost.
c. To assemble this type of modular devices, poka-yoke is needed and special
instructions are required otherwise there might be chances of wrong assembly.
Accordingly, there exists a need to provide a single pole switchgear device having a housing that eliminates need of a separate cover and overcomes the drawbacks of the prior art.
Objects of the invention

An object of the present invention is to provide identical housings for a switchgear device that acts as a common structure for a housing as well as a cover.
Another object of the present invention is to construct identical housings enabling the switchgear device to be assembled on any of the housings.
Summary of the invention
Accordingly, the present invention provides a switchgear device. The switchgear device comprises at least two housings. A first housing of the at least two housings comprises a first support member, an operating mechanism, a plurality of inter-phase barriers, a second support member, a plurality of stacking means, a first terminal unit secured inside the first housing, a third terminal unit secured inside the first housing opposite to the first terminal unit, a left source separator and a right source separator positioned inside the housing on a left side and a right side thereof, a second terminal unit secured on a top surface of the left source separator, a bridge unit having a first stopper positioned inside the housing and a bridge placed on a top surface of the first stopper, a pair of din-clips secured to the housing, the pair of din clips adapted to receive the left source separator and the right source separator thereon, and a knob adapted to operate the operating mechanism to any one of ON, OFF and TRIP positions of the switchgear device. A second housing of the at least two housings is capable of being secured to the first housing by a bridge pin thereby forming a single pole switchgear device thereby eliminating need of a separate cover to form the single pole switchgear device.
Brief description of drawings
Figure 1 shows an overall dimension of a switchgear device, in accordance with the present invention;

Figure 2 shows an exploded view of the switchgear device, in accordance with the present invention;
Figure 3shows an exploded view of at least two housings of the switchgear device of figure 1;
Figure 4 shows a side perspective view of a first terminal unit of the switchgear device of figure 1;
Figure 5 shows a side perspective view of a second terminal unit of the switchgear device of figure 1;
Figure 6 shows a side perspective view of a third terminal unit of the switchgear device of figure 1;
Figure 7 shows a side view of a pair of source separators of the switchgear device of figure 1;
Figure 8 shows a side perspective view of a bridge unit of the switchgear device of figure 1;
Figure 9 shows a moving contact assembly of the bridge unit of figure 8;
Figure 10 shows a knob of the switchgear device of figure 1;
Figure 11 shows a din-clip of the switchgear device of figure 1;
Figure 12 shows an assembly view of the switchgear device of figure 1; and
Figure 13 is an exploded view showing assembling of components of the switchgear device of figure 1.

Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
The present invention provides a switchgear device. The switchgear device includes at least two housings that eliminate need of a separate cover. The housings when placed over one another forms a single pole switchgear device thereby eliminating need of a separate cover to form the single pole switchgear device. The housing is made such that, assembly is done on any of the housing.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.
Figure 1 shows overall dimension of a switchgear device (200). Specifically, the switchgear device (200) is a modular changeover switch having dimensions of width=17.5mm (1-Mod), height=100.6mm and depth=75.1mm. Specifically, the switchgear device (200) is a Modular changeover switch in which two box clamps are accommodated in one Mod place for 40A switch. However, it is understood that the other modular devices like miniature circuit breaker (MCB), isolator, modular changeover, earth leakage miniature circuit breaker (EL-MCB) and automatic changeover with current limiter (ACCL) with varying dimensions may be used in other alternative embodiments.
A modular changeover switch is a device that transfers load from one source to other source. In an embodiment, the modular changeover switch includes two incoming supplies that is one source-I (S-I) and another source-II (S-II) and one

outgoing terminal (L) which is common terminal for both the sources (S-I and S-II).
Referring to figures 2-11, the switchgear device (200) in accordance with the present invention is shown. The switchgear device (200) includes at least two housings i.e. a first housing (10) and a second housing (20), a first terminal unit (30), a second terminal unit (40), a third terminal unit (50), a left source separator (60), a right source separator (70), a bridge unit (90), a knob (100) and a pair of din-clips (110).
As shown in figure 3, each housing of the at least two housings (10, 20) includes a first support member (A), an operating mechanism (B), a plurality of interphase barriers (C), a second support member (D) and a plurality of stacking means (E). No need of poka-yoke in the housings (10, 20) with these features.
The first terminal unit (30) (figure 4) includes a first terminal (22), a first button (24), a first box clamp (26) and a first termination screw (28). The first terminal unit (30) is used as a source-I incoming terminal.
The second terminal unit (40) (figure 5) includes a second terminal (32), a second button (34), a second box clamp (36) and a second termination screw (38). The second terminal unit (40) is used as a source-II incoming terminal.
The third terminal unit (50) (figure 6) includes a third terminal (42a), a fourth terminal (42b), a first set of pair of buttons (44), a third box clamp (46) and a third termination screw (48). The third terminal unit (50) is used as a common outgoing terminal (L) for source-I (S-I) and source-II (S-Il).
Figure 7 shows the left source separator (60) and the right source separator (70).
The source separators (60, 70) separate two sources (source-I and source-II) and include a left and right indication (not shown) for easy reference.

As shown in figure 8 and 9, the bridge unit (90) includes a bridge (72), a pair of moving contact assemblies (78), a first stopper (80) and a contact spring (82). In an embodiment, the pair of moving contact assemblies (78) is used for source-I and source-II that provides contact pressure at contact joints. The pair of moving contact assemblies (78) includes a pair of moving contacts (74) and a second set of pair of buttons (76). The contact spring (82) is used to maintain contact pressure at joints. The bridge unit (90) also includes a second stopper (not shown) and a mechanism spring (not shown) adapted to operate in ON-I, OFF and TRIP positions of the switchgear device (200).
The knob (100) is adapted to operate the operating mechanism and also to indicate ON, OFF and TRIP positions of the switchgear device (200). The pair of din-clips (110) is secured to the housings (10, 20) and adapted to receive the left source separator (60) and the right source separator (70) thereon.
Referring now to figures 12 and 13, an exploded view of the switchgear device (200) consisting of all units and at least two housings (10, 20) is shown. Specifically, construction of the switchgear device (200) is explained in conjunction with figure 1. In a first step for constructing the switchgear device (200), the first terminal unit (30) is placed in the first housing (10). Any housing of the pair of housings (10,20) may be used as a left housing or a right housing. In an embodiment, the housing (10) is used for an exemplary construction of the single pole switchgear device.
In next step, the third terminal unit (50) is placed in the first housing (10). Further, the left source separator (60) and the right source separator (70) is placed in a left side and a right side of the first housing (10). Furthermore, the second terminal unit (40) is placed on a top surface (not numbered) of the left source separator (60). Thereafter, the first stopper (80) is placed in the first housing (10), and, the bridge (72) is placed on a top surface (not numbered) of the first stopper (80) followed by the mechanism spring and the second stopper.

The knob (100) is then placed in such a way that the knob (100) covers the bridge (72) followed by a bridge pin (not numbered). The switchgear device (200) is characterized in that, once all the components/units described above are placed in the first housing (10), a second housing (20) is placed and fitted over the first housing (10) thereby forming the switchgear device (200) in accordance with the present invention. The housings (10, 20) when placed over one another forms a single pole switchgear device thereby eliminating need of a separate cover to form the single pole switchgear device.
Advantages of the invention
1. Single plastic mold is required, by making housing and cover construction common. With this the overall cost of tooling reduces and productivity increases and hence the final product cost reduces.
2. By making housing and cover common, commonizing the some of the components like terminal, source separator and like becomes easy.
3. To assemble this type of modular devices, no need of poka-yoke enabling easy assembling of all components.
4. Unique construction of housing. Same housing when assembled face to face forms a modular pole thereby reducing number of components and hence tooling investment.
5. Design poka yoke to avoid wrong assembly when a pole is constructed using two housings (10,20).
6. Simplified construction of housings (10,20) to minimize use of side core in the tool.
7. The construction of housing is such that, the housing is used as a same cassette for housing and cover in modular devices.
8. The housing is made such that, assembly is done on any of the housing.
9. The construction of housing is such that, fixed terminal is commonized.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not

intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.

We Claim:
1. A switchgear device comprising at least two housings, a first
housing of the at least two housings comprising:
a first support member, an operating mechanism, a plurality of interphase barriers, a second support member, a plurality of stacking means, a first terminal unit secured inside the first housing, a third terminal unit secured inside the first housing opposite to the first terminal unit, a left source separator and a right source separator positioned inside the housing on a left side and a right side thereof, a second terminal unit secured on a top surface of the left source separator, a bridge unit having a first stopper positioned inside the housing and a bridge placed on a top surface of the first stopper, a pair of din-clips secured to the housing, the pair of din clips adapted to receive the left source separator and the right source separator thereon, and a knob adapted to operate the operating mechanism to any one of ON, OFF and TRIP positions of the switchgear device, characterized in that,
a second housing of the at least two housings is capable of being secured to the first housing thereby forming a single pole switchgear device thereby eliminating need of a separate cover to form the single pole switchgear device.
2. The switchgear device as claimed in claim 1, wherein the second
housing is secured to the first housing by a bridge pin.