A) TECHNICAL FIELD

[0001] The present invention generally relates to interlock mechanism for switching devices and particularly to flexible cable type interlock mechanism for switching devices. The present invention more particularly relates to providing interlock assembly to prevent simultaneous closure of one or more circuit breakers.

B) BACKGROUND OF THE INVENTION

[0002] Switching devices are widely used in domestic, commercial and light industrial installations. Circuit breakers such as Miniature circuit breakers (MCB) are used where the supply voltage exceeds 200 V AC and are used to protect circuits rated up to 100 A from overload and ort circuit faults. It is common to restrict the circuit breaker movement, particularly, to prevent unintended operation of one or more of individual circuit breakers. The limiting of breakers from OFF to ON, is desirable in situations where multiple power sources are used to supply a limited number of energy consuming devices.

[0003] Currently various types of mechanical interlock are available for switching devices. A walking beam type interlock mechanism is applicable for only two breakers, wherein only one circuit breaker is ON at any time. The interlock includes a pivoting rocker arm and a linkage assembly associated with each of the circuit breakers. Another type of interlock mechanism uses sliding bar arrangement fitted on the switching devices. However, the currently available interlock mechanisms are complex in nature. The circuit breakers must be partially dismantled to install interlock systems. Further, the circuit breakers must be mounted at fixed distance. Moreover, the interlock mechanisms are applicable for only two drcuit weakos mid the number of flexible cables required in the interlock mechanian is nMn. Furthermore, the interlocking mechanism prevoits use of Electrical Operating Meduonans (EOM) like front accessories.

[0004] Hence, there exists a need to provide an cSfidetA flexible le interlocking mechanism for switching devices such as circuit breakors to prevent three circuit breakers from being closed (ON position) at same time. Also there exists a need to provide a simple interlodc mechanism for tiiree switching devices. Further, ihere «cists a need to provide interlock mechanism applicable for the switching devices of different frame sizes.

[0005] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.

C) OBJECT OF THE INVENTION

[0006] The primary object of the present invention is to provide a flexible cable interlocking mechanism for switching devices to prevrat three circuit breakers from being in closed position or ON position at same time.

[0007] Another object of the present invention is to provide a simple flexible cable interlocking mechanism for three switching devices.

[0008] Another object of the present invention is to {Hovide a flexible cable interlocking medianism applicable for the switching devices of different fitone sizes.

[0009] Yet anothw object of the inresent invention is to provide a flexible cable interlocking mechanism to provide for holding sub modules integrated into each of circuit breakers mi to convert angjilar movonoit of knob associated with the circuit breaker into linear movement.

[0010] Yet another object of the present invoition is to provide a cortral module with a cable holder to hold other end of fledble cable.

[0011] Yet another object of the present invention is to provide a central module which has links arrangement to achieve seven possible switching combinations among three circuit breakers.

[0012] Yet another object of the present inventicm is to iovide a flexible interlocking mechanism for circuit breakers whidi isures easy site installation by a custcono.

[0013] Yet another object of the present invention is to provide an interlocking mechanism for a fixed type circuit breaker, or witfidraw able type circuit breaker or plug-in type circuit breaker.

[0014] Yet another object of the present invention is to jnovide an into-locking mechanism applicable to same pole or different pole switching devices.

[0015] Yet another object of the present invention is to provide interlocking mechanism which is easy to manufacture.

D) SUMMARY OF THE INVENTION

[0016] The various embodiments of the present invention provide a flexible cable interlocking mechanism for switching devices sudi as drcuit breakers to prevent three circuit breakers firom being closed posittcm or ON position at the same time. Exsonples of the switching devices include but are not limited to a fixed type circuit breaker, withdraw able type circuit hresker and plug-in type circuit breaker.

[0017] According to one embodimait of the eseiit invention m interlocking mhanism includes at least three sob modules and a central module. The interlocking mechanism is mounted to 8 ficntf surface of the switching device. A connection between each of die modules and the central module is made throu flexible cables. Eadi drcmt breaker is fitted to a sub module. The sub module includes guides fdiment of the in-esent invoition.

[0031] FIG. 10 illustrates a top paspective view of cable holder with the flexible cable fixed to the coitral module according to one embodiment of the present invention.

[0032] Although ecific features of the present invention are shown in some drawings and not in otha:s. This is done for convenience only as each feature may be combined with any or all of the other feature in accorduice with the present invention.

F) DETAILED DESCMPTION OF THE Eect to FIG. 1, the sub module includes a left side guide rail 1 and a rit side guide rail 3 which are of similar shape boided symmetricly. A slider 4 is provided which slides smoothly on the guide rails 1 smd 3. A cable holder 2 is fitted to the guide raih 1,3. In order to hold aaad give tmntkmd movement for slider 4, the left and right side guide rails 1, 3 are provided. The slider 4 is jwovided to convert the angular movement of the switdring device knob 9 (as shown in FIG. 2) to linear movement. The slid«- 4 also receives one ead of iimer wire of flexible cable 13. Tlw flexible cable holder

2 is provided to hold one end of the flexible cable 13 (as shown in FIG.3). In the sub module the inner cable is locked with the slider by means of an op«iing slot. The cable holder 2 is fitted by means of screws 8 (as own in FIG. 2). The cable holder 2 also supports the left and right side guide rails 1,

3 to prevent the shaking of the rails 1, 3. The sub module arrangement does not require any modification in the switching devices. This provides for fixing the sub module to the switching device which is already in service. The sub module components and arrangemt are provided to convol angular movement of the knob to linear movement.

[0040] FIG. 2 illustrates the assembling of the interlocking assembly with the switching device according to one embodiment of the prent invoition. With respect to FIG. 2, the sub module is fitted to the switdiing devices 10 by means of two screws 7. The switching device includes an outer cover 5 and a release outer cover 6. The cable holder 2 (as shown in FIG.I) is fitted with the guide rails by means of two screws 8. The sub module assembly is made such that the slider 4 holds knob 9 of switching device 10 in it.

[0041] The flwcible cable is provided to transmit pidling force fi-om the switching device 10 to the central module. One end of the flexible cable is fitted by means of lock nuts or other suitable means to die csSsAe holder 2. The sub module components and the arrangement convert angular movement of the knob of the switching device mto linear movement The integration of the sub module with the switching ctevices involves only two screws to fit with the switching device which is assembled easily at site of the switching device by a customer.

[0042] FIG. 3 illustrates a side perspective view of sub module fitted to switching device according to one embodiment of die present invention. With respect to FIG. 3, (me end of flexible cable 13 is fitted to the sub module by means of cable holder 2. Hie inner wire 12 of the cable is locked with the slider 4 of the sub module in any suitable way. Furdier, fixtures 11 are used to fix the one end of the flexible cable 13 with the cle holder 2.

[0043] The flexible cable 13 is provided to transmit pulling force fi-om the switching device 10 to the central module. ODB end of flexible cable is fitted by means of lock nuts or other suitable means to die cable lK>ldar 2. The sub module components and arrangement convots angular movement of the knob of the switching device into linear movement,

[0044] FIG. 4 illustrates a top perspective view of partially assembled central module of the interlocking assembly according to one embodiment of the present invition. With respect to FIG. 4, tiM central module 25 is provided wifli a base 22, a cable holder 14, guide rails 16, a slider 18, a stopper 17, and a pin IS. CMe end of flexible cable 13 is fitted to the sub module by means of a cable holder 2. The other end of the flexible cable is fitted with a central module cable holder 14 by lock nuts 23 (FIG. 7). The case 22 is provided to support the central module omiponents. The flexible cable holder 14 is fitted with base 22 to hold one end of the flexible cable. The shape of the flexible cable holder is made to hold the cable. The pin 15 is provided to hold the one end of the link assembly fitted on flie base 22. The central module's 25 guide rails 16 are provided to give translational movement to the slido' 18. The slider 18 fitted with link assembly (FIG. 5) slides on guide rails 16 during switching operation of flie switching devices.

[0045] FIG. 5 illustrate a top perspective view of the links provided in the central module of the interlocking assembly according to one embodiment of the iesent invoition. With respect to FIG. 5, to links 19 are cded with 'L' shaped bends 20 connected to two nod (a)nnectmg point of two links) of the lii 19. The 'L' bend 20 is jnovided to hold one end of the inner wire of the flexible cable. Hence trmsmiioD of pulling force is accomplished from switching device to the central module. The links 19 provide seven possible switching combinations for the ee switching devices as shown in the below table. From the below table A, B, C are the three switching devices, wherein' 1' represeate ON state of the circuit breaker and '0' represorts OFF state of the circuit tn'eaker.

[0046] FIG. 6 illustrates a top perspective view of central module of the into-locking mechmiism according to one embodiment of the prent invention. With respect to FIG. 6, the central module 25 is jwovided with a base 22, a cable holder 14, guide rails 16, a slider 18, a stopper 17, and a pin 15. One end of flexible cable 13 is fitted to the sub module by means of cable holder 2. The other end of the flexible cable is fitted wiA a central module cable holder 14 by lock nuts 23. The base 22 is jnovided to support central module compcments. The flexible cable holder 14 is fitted with base 22 to hold one «id of the flexible cable 13. The s&ape of flacible cable holder 2 is made to hold the cable. The pin 15 is iHOvided to hcM fee one end of the link assembly fitted on the base 22. The central module's 25 guide rails 16 are IMTOvided to give translational movement to the slider 18. The slider 18 fitted with link assembly (FIG. 5) slides on the guide rails 16 during switching operation of flie switching devices.

[0047] The links 19 are provided with 'L' bends 20 connected to two nodes (connecting point of two links) of tfie links 19. The 'L' bwid 20 is provided to hold one &ad of the inner wire of ike HexMe cable. The transmissi(m of the pulling force is accomplied fit»n switdiing device to the central laodide. The links 19 provide seven possible switching combinations for e three switching devices as own in the below table. From the below table A, B, C are the three switdiing devices, wherein T represents ON state of the circuit breaker and '0' rqmesents OFF state of the circuit breaker.

[0048] The above arrangement of the links 19 on the base 22 of the central module 25 provides a force transmissicm between the switching devices to the central module 25. The cable holder 14 is made of a simple sheet metal component with a 'U' shaped slot. Two lock nuts or a screw from two sides of the cable holder is used to fix the liable cable in the cable holder 14.

[0049] FIG. 7 illustrates a perspective view of the central module of the into-locking assembly with one end of flexible catole fitted to the central module according to one onbodiment of the presoit invention. With respect to FIG. 7, the central module 25 is fitted with one end of the flexible cable by means of lock nuts 23.

[0050] FIG. 8 illustrates various arrangements of links in a coitral module of interlocking assembly, crexiKiing to kack position of switcng devices accwding to one embodiment of the present invaition. With respect to FIG. 8a, initially all three switching devices are in OFF position. The grajA shown below reja-esoits the links arrangemait with reelect to FIG. 8a. At this state the links in the central module a, b, c and d are free to move. With respect to FIG. 8b, during switching ON operation of tibird switching device, one end of the link d connected with the central module slider moves right side as shown below in the h.

[0051] With respect to FIG 8c, after switching ON the third switching device, during switching ON operation of the second switching device prevents the sliding of the link d since the tfiird switching device in ON position. Hence, the joint connecting link b and c iMily moves right side as shown below in the"graph. At this state switching the firat switching device is prevented.

[0052] With respect to FIG. 8d, during swiudif ON operation of the first switching device since £he third switching vice is ah-y in ON position it prevents sliding of the link d. Hence, the joint connecting link b & c only moves towards left side as shown below in the graph. At this state switching of the second switching device is prevented.

[0053] FIG. 9 illustrates the top perspective view of the interlocking assembly connected to three switching devices throu tiiree flexible cables according to {mother embodiment of the present invention. With respect to FIG. 9, the switdiing devices 10a, 10b and 10c are OHuiected to interlock assembly which includes a caitral module 25. The switching devices 1 Oa, 1 Ob and 1 Oc are connected to the central module 25 throu£ flecible cables.

[0054] The force applied to switch the switdiing device knob is transmitted to the central module 25 through the flexible cable 13. Thus, a change in the circuit breaker knob position csmes a change in the arrangement of the links provided in the central module. Tl mxangemoit of the links in the central module 25 allows closing at most two circuit breakers at a time avoiding svwtching ON all three circuit tedcers at a time. Hraice desirable interlodcing between the three circuit too&os is achieved. The SEVEN possible switching combinations of the circidt l»reakers are shown in the below table. From the below table A, B, C are tt tocc switching devices 10a, 10b, and 10c, wherein '1' rqjresents ON state of fiie circuit breaker and '0' represents OFF state of the circuit breaker.

[0055] Initially all the three circuit breakers are in open position (OFF position).One requirement for the Interlock mechanism is that all of the switching devices are in the opai position before movonent of any switch to closed position (ON position). Further, during closing of any one of the switches, the arrangement of links in the central module 25 changes. After switching one of the three switching devices, switdung ON any one of the remaining two switching devices is possible. Thus, again during ON operation of any one or the two switching devices arrangement of links in the central module again gets changed. After switching two switching devices further, svvatching ON of any of the switching devices is restricted by the interlock assembly. Thus the interlock assembly prevoits tlw three switching devices fix)m being closed (ON portion) at same time.

[0056] FIG. 10 illustrates a top perspective view of fixing a flocible cable to the cable holder of craitral module acccmling to (me embodiment of the present invention. With respect to FIG. 10 one aid of the flexible cable is fixed to cable holder 14 of the central module (as isliowii in FIG.6) using side screws 24.

G) ADVANTAGES OF THE INVENTION

[0057] The various embodimoits of the ineot invoition provide a simple flexible cable interlocking mechanism for swindling devices such as circuit breakers to prevent three circuit brikos fixnn bdng closed (ON position) at same time. The switching devices can be placed in any desired location while interlocking without providing rerkon for a customer to place the switching devices at a specified £stan(%. The interlocking mechanism is to the switching devices which are abeiKiy in service without any modifications in the switching device.

[0058] The present invention provides &e interiocking mechanism applicable for the switching devices of diffo'ent fione sizes. The interlocking mechanism ensures easy si|e installation by a customar. The interlock mechanism allows use of Electrical Opoating Medianian (EOM) Uke fi-ont accessories wifliout any change. Further, the interlocking mechanism is applicable to same pole or different pole switching devices. Moreover, the interlocking mechanism is made of sheet metal ctanpcments which are easier to manufacture and thus, reduces manufacturing difficulty.

[0059] Although the invaition is described with various specific embodiments, it will be djvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of flie claims.

[0060] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.

CLAIMS
What is claimed is:

1. An interlock mechanism for switching devices, the mechanism comprising: at least three sub modules; a central module;
a plurality of links provided in the central module;
a flexible cable connecting each of the sub module and the central module; and a knob;
wherein a mechanical force applied to the knob is transferred to the central module through the flexible cable such that a change in the knob position changes the arrangement of the plurality of links to provide for interlocking.

2. The interlock mechanism according to claim 1, wherein each of the sub-
module comprising:
a guide; and
a slider adapted to slide on the guide.

3. The interlock mechanism according to claim 1, wherein the central module
comprising:
a guide rail;
a pin; and
at least two sliders adapted to slide in the guide;
wherein the at least four links, guide rail, the pin, and the at least two sliders are
assembled in a base plate.

4. The interlock mechanism according to claim 1, who the plurality of links includes four links.

5. The interlock mechanism according to claim 1, further comprising a flexible cable holder to hold at least one end of the cable.

6. The interlock mechanism according to claim 5, wherein the cable holder is a metal sheet component with a U-shaped slot.

7. The interlock mechanism according to claim 1, wherein each sub-module is mounted on the switching device using a screw.

8. The interlock mechanism according to claim 1, further comprising an L-bend which locks an inner wire of the cable to transmit force between a circuit breaker and the central module.

9. The interlock mechanism according to claim 1, wherein each of the at least three sub module is assembled on each circuit breaker such that the slider holds the knob of the circuit breaker.

10. The interlock mechanism according to claim 9, wherein the sub-module is adapted to transfer the angular movement of the knob to a liner movement during the circuit breaker switching operation.

11. The interlock mechanism according to claim 10, wherein at least three flexible cables we used for interlocking at least three switching devices.

12. The interlock mechanism according to claim 11, wherein one end of each flexible cable is attached to each sub-module and other end of each flexible cable is attached to the central module.

13. The interlock mechanism according to claim 1, wherein the arrangement of links in the central module provides for closing of at least two circuit breakers at a time.