FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
COMPLETE SPECIFICATION [See section 10; Rule 13]


A DEVICE FOR INTERLOCKING MULTIPLE SWITCHING DEVICES;


LARSEN & TOUBRO LIMITED A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS L&T HOUSE, BALLARD ESTATE, MUMBAI - 400 001, MAHARASHTRA, INDIA.

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THIS INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFOMED.

TITLE
A DEVICE FOR INTERLOCKING MULTIPLE SWITCHING DEVICES.
TECHNICAL FIELD
The present invention relates to an interlocking system for switching devices for opening and closing of intended number of switching devices simultaneously.
BACKGROUND ART
Generally, industrial electrical systems in which high-value currents and high power levels are involved use specific devices, commonly known in the art as circuit breakers / switching devices in order to ensure the correct operation of the electrical system in which they are installed and of the loads connected thereto. In certain practical applications, more than one circuit breakers are used and it is known in the art to interlock two or more circuit breakers so as to avoid potential undesired effect due to inadvertently closing of switching devices from a back-up power system when the switching devices of power source is closed for electric service utility.
Several interlocking systems are known in the art for such switching devices. EP 0890181 discloses a cable interlock system for preventing two circuit breakers from being closed at the same time, comprising a first circuit breaker having a first operating handle, wherein the first operating handle is adapted to close or open the first circuit breaker, a second circuit breaker having a second operating handle, wherein the second operating handle is adapted to close or open the second circuit breaker, a first mounting bracket that is attached or secured to or otherwise associated
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with the first circuit breaker, a first lever arm movably attached or secured to or otherwise associated with the first mounting bracket, a second mounting bracket that is attached or secured to or otherwise associated with the second circuit breaker, a second lever arm movably attached or secured to or otherwise associated with the second mounting bracket, a cable assembly having one end adapted to be connected to the first lever arm of the first mounting bracket and having another end adapted to be connected to the second lever arm of the second mounting bracket, wherein said cable assembly and the first lever arm and the second lever arm operate together so as to prevent the first operating handle and the second operating handle from both being in the closed position.
However, it can interlock maximum three circuit breakers only. Further, the circuit breakers may also be required to be mounted at a predetermined distance. In some interlock applications; the circuit breakers are required to be disassembled partially to install such a system. The available interlocking systems are not readily suitable when multiple circuit breakers are to be interlocked.
SUMMARY OF INVENTION
It is the object of the present invention to provide a mechanical interlock device suitable to interlock more than two circuit breakers that can be scalable to any required arrangement.
Another object of the present invention is to provide an interlocking device with simple construction of links having substantially less number of components.
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The present invention provides a device for interlocking multiple switching devices having a housing; lock members each being connected to a switching device, placed in said housing; a plate adapted to accommodate intended number of lock members for interlocking intended number of switching devices and switching "ON" intended number of switching devices. The plate according to the present invention is substantially "V" shaped to accommodate intended number of lock members. The lock members being connected to switching devices may be a roller. The switching devices are connected to the respective lock members by a cable. The cable passes through a slot provided on the plate. An adjustment plate is provided on the housing to adapt the cable and the lock member to the housing. The adjustment plate allows fine adjustments of the cable for individual switching devices. A compression spring is adapted between the lock member and the adjustment plate such a way that the lock member remains in an extreme state, corresponding to "OFF" position and the spring enables the lock member being pulled towards the plate for switching "ON" the switching device.
The main advantage of the present invention is multiple switching devices are interlocked by single interlocking device of the present invention.
The device for interlocking multiple switching devices according to the present invention enables closing intended number of circuit breakers according to the requirement of the user. Further, the device according to the present invention provides a freedom of arrangement of switching devices due to the flexibility of the cable length and the arrangement of the interlocking components thereby providing optimum usage of panel space.
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The device for interlocking multiple switching devices according to the present invention is safe, simple and is scalable to any required arrangement.
BRIEF DESCIRPTION OF DRAWINGS
Fig. 1 shows the perspective view of a device for interlocking multiple switching devices according to the present invention.
Fig. 2A shows the interlocking of the three switching devices in OFF position using the interlocking device according to the present invention.
Fig 2B shows the interlocking of the three switching devices allowing one switching device to be switched ON using the interlocking system according to the present invention.
Fig. 3 shows the interlocking device shows interlocking for five switching devices.
DETAILED DESCRIPTION OF THE INVENTION
The invention will be more clearly understood from the following description considered along with the schematic drawings.
The device (100) for interlocking multiple switching devices as shown in Fig 1 comprises a housing (10) enclosing lock members (30) and a plate (20). The housing has a base wall (12), two sidewalls (14) and front wall (11) and a back wall (13). The housing (10) is provided with a groove (not shown in figure) on the base wall (12) and a clamp (16) on the sidewalls (14) to adapt the plate (20) to the housing (10). The housing (10) is provided with holes (11) to mount said housing in a suitable place such as for example a wall. The size of the housing can be varied according to the
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number of lock members (30) and the size of the plate (20) to be
enclosed. '•■ £
The plate (20) is substantially "V" shaped and is adapted to the housing in a manner as described above. The plate (20) is adapted to accommodate intended number of lock members (30) within the "V" shape of the plate (20). According to an embodiment of the present invention, the plate (20) accommodates one to multiple lock members as shown in Fig 1 - 3, which are connected to corresponding number of switching devices. The plate (20) shall be made according to the number of lock members (30) to be adapted. Further, the shape of the plate (20) is not limited to "V" shape; any shape 'U', "W, "M' may be arrived at with respect to the size and shape of the lock members (30).
The lock members (30) according to the present invention are being connected to corresponding switching devices as shown in Fig 2A & 2B. According to an embodiment of the present invention, a lock member (30) is a roller. The lock member can be any block, geometrical of free form, a sphere and made of plastic, metal or the like. The lock member (30) hereinafter will be referred to as a roller. Each roller (30) is connected to a switching device (40) by a cable (32). One end of the cable (32) is connected to the operating handle of the switching device (operating handle 41A of switching device (40A) as shown in Fig 2A). Alternatively, the cable may be connected to the knob or shaft of the switching device (40) as required. The cable (32) according to the present invention is connected to the handle (41) of the switching device (40). According to an embodiment of the present invention, the cable for connecting the switching device is a clutch cable (32) as shown in Fig 1 -3. The other end
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of the cable (32) gets connected to the rollers (30), which are housed in the housing (10).
The switching devices (40) may be placed at a distance from the interlocking device (100). The length of the cable (32) may be adjusted for connecting the switching devices (40) to the lock members (30). The number of switching devices (40) defines the number of lock members (30) required to interlock said switching devices (40). Preferably, the switching devices (40) may be positioned at a distance from each other.
The plate (20) is provided with a slot (22) for passing the cable to connect the roller (30) to the switching device (40). Alternatively, the cable (32) may not be passed through the plate (20) to connect the switching device (40) and the roller (30). However, for effective functioning of the device (100), the inventors believe that the cable is passed through the slot (22). Further, separate cables are used to connect lock members (30A, 30B, 30C) to corresponding switching devices (40A, 40B, 40C) (shown in Fig 2A and 2B).
The present invention provides an adjustment plate (36) mounted on the housing (10). The adjustment plate (36) is provided with holes (not shown) to receive the cable (32) from the switching device through said adjustment plate (36) and pass the cable (32) through the plate (20) to connect the roller (30A, 30B, 30C) to corresponding switching devices (40A, 40B, 40C) (as shown in Fig 2). A compression spring (34) for each roller (shown in Fig 1) is provided between the adjustment plate (36) and the roller (30) such that the compression spring (34) hold the roller (30) in an extreme state, corresponding to "OFF" position as shown in Figurel
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and 2A. The cable (32) senses the switching motion of the switching device (40A) and pulls the roller (30A) to move inside the "V" shaped region of the plate (20). The plate (20) as shown in Fig 2A has a profile to get accommodated only one roller (30A) in the "V" shaped region of the plate (20) allowing switching ON of switching device (40A) as shown in Fig 2B. The switching "ON" of the switching devices is dependent on the physical movement of the rollers. This arrangement of the plate (20) provides no room for additional rollers (30B, 30C) and thereby preventing the corresponding switching devices (40B, 40C) from being switched "ON" as shown in Figure 2B.
Further, the adjustment plate (36) also allows fine adjustments for individual switching devices and cable since the switching devices are at difference places with the rollers (30) to enable the rollers (30) sense the switching motion of the switching device (40) and moves from one extreme position to other on switching ON or OFF the switching devices (40).
The interlocking devices as shown in Fig. 3 are as designed for interlocking five switching devices that allows closing of two to four switching devices simultaneously. Thus, changing the profile of the plate (20) or the size of the rollers can modify the device according to the present invention.
The device (100) for interlocking multiple switching devices according to the present invention is made of nylon - molded. However, any suitable polymer / fabricated part such as metal, plastic may be used for construction of said device.
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The device for interlocking multiple switching devices according to the present invention enables closing or opening intended number, of circuit breakers and interlock any number of switching devices according to the requirement of the user. Further, the device according to the present invention provides a freedom of arrangement of circuit breakers within the enclosure due to the flexibility of the cable length and the arrangement of the interlocking components thereby providing optimum usage of panel space.
The device for interlocking multiple switching devices according to the present invention is safe and is scalable to any required arrangement.
The device (100) according to the present invention is compact and is easy to handle. The installation of the device (100) is substantially simpler compared to the prior art devices. Further, using a single interlocking device, multiple circuit breakers can be interlocked according to the requirement. The device (100) according to the present invention can be constructed and custom built according to the requirement.
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WE CLAIM
1. A device for interlocking multiple switching devices comprising :
a housing;
lock members each being connected to a switching device, and placed in said housing;
a plate adapted to accommodate intended number of lock members for interlocking intended number of switching devices and switching "ON" intended number of switching devices.
2. The device for interlocking multiple switching devices as claimed in claim 1 wherein the plate is substantially "V" shaped to accommodate intended number of lock members.
3. The device for interlocking multiple switching devices as claimed in claim 1 wherein the lock members being connected to switching devices is a roller.
4. The device for interlocking multiple switching devices as claimed in claim 1 wherein a cable connects the switching devices to the corresponding lock members.
5. The device for interlocking multiple switching devices as claimed in claim 2 wherein the plate has a slot for passing the cable to connect the lock member.
6. The device as claimed in claim 1 to 5 wherein an adjustment plate adapts the cable and the lock member to the housing and allows fine adjustments of the cable for individual switching devices.
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7. The device as claimed in claims 1 to 6 wherein a compression spring
is adapted between the lock member and the adjustment plate such that
the lock member remains in an extreme state, corresponding to "OFF"
position.
8. The device as claimed in claims 1 to 7 wherein said device can be
scaled for accommodating multiple number of switching devices by
changing the profile of the plate and/or size of the rollers.
Dated this 18th day of March, 2005.
FOR LARSEN & TOUBRO LIMITED By their Agent

(UMA BASKARAN) KRISHNA & SAURASTRI)