FORM 2
The Patents Act 1970
(39 of 1970)
&
The Patent Rules 2003
COMPLETE SPECIFICATION
(See Section 10 and rule 13) TITLE OF THE INVENTION:
ELECTRICAL CONTACT SYSTEM FOR CLOSE DOOR TEST POSITION OF
SWITCHBOARD MODULES


APPLICANT:
LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No. 278,
Mumbai, 400 001, Maharashtra . INDIA.
PREAMBLE OF THE DESCRIPTION:
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

A) TECHNICAL FIELD
[0001] The present invention generally relates to an electrical switchboards and particularly to an electrical contact system in switchboard modules to isolate the power contacts in the switchboard module and to move the switchboard module from the service position to a test position without opening the door of the switchboard module.
B) BACKGROUND OF THE INVENTION
[0002] Electrical isolation in switchboards is an important factor for both manufacturers and consumers. The electrical isolation is provided between electrical contacts in the switchboards to physically separate the hazardous circuits and transient sources from the users and to protect the products and their surroundings. The electrical isolation prevents an unacceptable current from flowing as a result of a potential AC or DC difference between the circuits. The safety isolation device protects the measurement products and the users from the electrical hazards.
[0003] The electrical contacts typically provide an interface between the current-carrying members of electrical or electronic devices. A draw-out apparatus is typically designed to support the electrical device for racking movement between an extended position well out of a compartment and an engaged position within the compartment where the load current carrying primary contacts of the device and compartment are fully engaged.
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[0004] The electrical devices, such as circuit breakers for industrial applications, are typically equipped with a variety of accessorial functions served by the external auxiliary circuits and provisions must be made for making and breaking these auxiliary circuits as the device is moved between its extended and engaged positions. To this end, the so-called mating secondary disconnect contacts are mounted with the device and the compartment. The secondary disconnects are engaged when the device is in the engaged position and are disengaged at some point during the movement of the device out to the disengaged position.
[0005] The switchboard modules are operated in three distinct positions namely service, test and isolated positions. The service position is one in which the module is fully inserted into the housing or module or circuit breaker compartment and the power and control contacts are fully made. In test position the power contacts are isolated but the control circuit is still connected. The test condition is essential to facilitate testing of the control circuits with functional interlocks, without energizing the connected load. In isolated position both the power and control circuits are isolated.
[0006] It is common practice to provide a test position for the switchboard modules to intermediate its engaged and disengaged positions, where the power connectors are separated but the auxiliary connectors are still engaged. In this test position, the accessorial functions can be thoroughly tested and hence provide safety factor for the panel operator while working on it.
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[0007] The operation of the withdrawal equipment, such as a breaker or components on a removable chassis, is not possible unless it is in service, test, isolated or totally removed positions.
[0008] Currently the operator has to open the door before racking out the switchboard module when he wants to move the switchboard modules from service position to test position i.e. to isolate the power contacts. It is a tedious process and may result in electrical hazard during maintenance or service process. Hence there is a need to develop an electrical contact mechanism for switchboard modules so that the module is moved from the service to test position without opening the door or switchboard panel.
C) OBJECTS OF THE INVENTION
[0009] The primary object of the present invention is to provide an electrical contact system to isolate the power contacts in the switchboard module and to move the switchboard module from the service to test position without opening the door of the switchboard panel.
[0010] Yet another object of the present invention is to provide an electrical contact system which offers low contact resistance during racking in and racking out of the switchboard modules.
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[0011] Yet another object of the present invention is to provide an electrical contact system with an interlocking mechanism to prevent the racking-out of the switchboard module, when the short circuit protective device is switched ON.
[0012] Yet another object of the present invention is to provide an electrical contact system for switchboard modules to ensure safety of the panel operator during maintenance or service process.
[0013] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
D) SUMMARY OF THE INVENTION
[0014] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
[0015] The various embodiments of the present invention provide an electrical contact system to isolate the power contacts in the switchboard module during test position. The electrical contact system comprises a compact molded power contact kit with a racking rod assembly mounted inside a switchboard panel to operate the switchboard module from service position to test position without opening the door of the switchboard panel.
[0016] According to one embodiment of the present invention, an electrical contact system is provided with a molded power contact kit and a racking rod to move the switch
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board modules provided with fixed power contacts and dropper power contacts, to a test position from the service position. The system has a molded power contact kit mounted on a chassis plate installed in the switchboard module. The molded power contact is arranged with pluralities of sliding jaw contacts and pluralities of isolating jaw contacts. The system has pair of guide rails mounted on the chassis. A movable guide is attached to both the side ends of the molded power contact kit and moved along the guide rails. A rotatable racking handle is coupled to a racking nut which is attached to the bottom of the molded power contact kit. A racking handle is detachably attached to the racking rod to rotate the racking handle to move the molded power contact mechanism to bring the switch board module to a test position from the service position. An interlock mechanism is provided to prevent the rotation of the rotation of the racking rod to prevent the movement of the switchboard module from the service position to test position without switching off a protective device.
[0017] The racking handle is detachably attached to the racking rod by inserting the racking handle through a shutter provided on the door of the switchboard module. The racking handle is rotated in anti clock wise direction to move the racking rod to move the molded power contact kit to move the pluralities of isolating jaw contacts from the respective dropper power contacts provided in the switchboard module to move the switchboard module from the service position to test position, without opening the door of the switchboard module. As the racking rod is rotated, the guides are moved along the guide rails to move the molded power contact kit to make the isolating jaw contacts to make and break contacts with the dropper power contacts. The sliding jaw contacts are made to contact the fixed power contacts mounted on the chassis plate of the switchboard
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module, even when the molded power contact kit is moved to shift the switchboard module from the service position to test position.
[0018] The interlock mechanism has a plunger fixed near the racking rod to obstruct the movement of the racking rod to prevent the movement of the switchboard module from the service position to test position, when the protective device is switched on. The interlock mechanism further comprises a gear wire attached to the plunger and to a protective device handle which is arranged on the switchboard module. The gear wire is moved to displace the plunger towards the racking rod to make the plunger to contact the racking rod to prevent the movement of the racking rod to stop the movement of the switchboard module from the service position to test position, when the protective device is switched on. The gear wire is moved to displace the plunger away from the racking rod to permit the rotation of the racking rod to move the switchboard module from the service position to test position, when the protective device is switched off. A pin is further provided on the racking rod to permit or to prevent the rotation of the racking rod. The gear wire is moved to displace the plunger towards the racking rod to make the plunger to contact the pin on the racking rod to prevent the rotation of the racking rod, when the protective device is switched on.
[0019] According to one embodiment of the present invention, the electrical contact system includes a fixed power contact mounted on a chassis plate arranged inside the switchboard panel. The molded power contact kit is mounted on the chassis plate. The molded power contact kit is a main moving part which can be racked in or out of the
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switchboard module using a racking rod to achieve the test position without opening the door of the switchboard panel.
[0020] The compact molded power contact kit assembly includes a guiding rail and a moving guide. The fixed guiding rail is mounted on a chassis arranged inside the switchboard. The moving guide is attached to both the side ends of the molded power contact kit. The molded power contact kit is mounted on fixed guiding rail with the guide movably attached to it. The movable contact kit includes a sliding jaw contact and an isolating jaw contact. The sliding jaw contact engages with the fixed contact terminal in the switchboard module and the isolating jaw contact is connected to a power supply dropper. The molded power contact kit is engaged with the racking rod through a racking-nut which is fixed at the bottom of the molded power contact kit. The power contacts are isolated by using the racking rod which is rotated with the help of a detachable racking handle in anticlockwise direction to bring the switchboard module from the service position to test position.
[0021] A shutter cum barrier is provided on the door of the switchboard module to access the racking rod. To operate the switchboard module from service to test position, the shutter is removed to access the racking rod and the racking rod is rotated with the help of detachable racking handle in anticlockwise direction to move the molded power contact kit reciprocatably as the molded power contact kit is engaged with the racking rod through racking-nut that is fixed at the bottom of molded power contact kit. The guiding rail has a stopper to restrict the movement of molded power contact kit in a fixed direction.
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[0022] The stopper is provided on the guiding rail to restrict the move the guide only by a preset distance for example by 30 mm. As the switchboard module is racked out with the help of the racking rod, the isolating jaw contact of the molded power contact kit isolates the power supply from the droppers. However the sliding jaw contacts of molded power contact kit always remain in contact with fixed power contact.
[0023] An interlocking mechanism is provided so that the switchboard module is not moved to test position, when the short circuit protective device is switched ON. Hence it is not possible for the operator to move the switchboard module to test position without switching OFF the protecting device. In order to support the interlocking of the switchboard module, a separate pin is provided on the racking rod and a plunger is fixed near racking rod which obstructs the rotation of racking rod with the help of a gear wire coupled to the protective device handle. The pin allows the rotation of the racking rod, only when the protective device is switched OFF. Once the module is brought to test position, the operator can safely do the maintenance or service process.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which;
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[0025] FIG. 1 shows a top side view of the electrical contact system for switchboard modules, according to one embodiment of the present invention.
[0026] FIG. 2 shows a rear side perspective view of the electrical contact system for switchboard modules, according to one embodiment of the present invention.
[0027] FIG. 3 shows a side view of the switchboard module provided with an electrical contact system, according to one embodiment of the present invention.
[0028] FIG .4 shows a top side perspective view of the molded power contact kit provided in the electrical contact system according, to one embodiment of the present invention.
[0029] FIG. 5 shows a top view of the molded power contact kit provided in the electrical contact system, according to one embodiment of the present invention.
[0030] FIG. 6 shows a top view of the electrical contact system for switchboard module in service position, according to one embodiment of the present invention.
[0031] FIG. 7 shows a top view of the electrical contact system for switchboard module in test position, according to one embodiment of the present invention.
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[0032] FIG. 8a and 8b show a top view of the electrical contact system with an interlocking mechanism in service and test position according to one embodiment of the present invention.
[0033] FIG. 9 shows a side view of the racking handle provided in the electrical contact system, according to one embodiment of the present invention.
[0034] FIG. 10 shows a front view of the racking rod provided in the electrical contact system, according to one embodiment of the present invention.
[0035] Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.
F) DETAILED DESCRIPTION OF THE INVENTION
[0036] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
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[0037] The various embodiments of the present invention provide an electrical contact system to isolate the power contacts in the switchboard module during test position. The electrical contact system comprises of a compact molded power contact kit and a racking rod assembly mounted inside a switchboard panel to operate the short circuit protective device in the switchboard module from the service position to test position without opening the door of the switchboard panel.
[0038] According to one embodiment of the present invention, an electrical contact system is provided with a molded power contact kit and a racking rod to move the switch board modules provided with fixed power contacts and dropper power contacts, to a test position from the service position. The system has a molded power contact kit mounted on a chassis plate installed in the switchboard module. The molded power contact is arranged with pluralities of sliding jaw contacts and pluralities of isolating jaw contacts. The system has pair of guide rails mounted on the chassis. A movable guide is attached to both the side ends of the molded power contact kit and moved along the guide rails. A rotatable racking handle is coupled to a racking nut which is attached to the bottom of the molded power contact kit. A racking handle is detachably attached to the racking rod to rotate the racking handle to move the molded power contact mechanism to bring the switch board module to a test position from the service position. An interlock mechanism is provided to prevent the rotation of the rotation of the racking rod to prevent the movement of the switchboard module from the service position to test position without switching off a protective device.
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[0039] The racking handle is detachably attached to the racking rod by inserting the racking handle through a shutter provided on the door of the switchboard module. The racking handle is rotated in anti clock wise direction to move the racking rod to move the molded power contact kit to move the pluralities of isolating jaw contacts from the respective dropper power contacts provided in the switchboard module to move the switchboard module from the service position to test position, without opening the door of the switchboard module. As the racking rod is rotated, the guides are moved along the guide rails to move the molded power contact kit to make the isolating jaw contacts to make and break contacts with the dropper power contacts. The sliding jaw contacts are made to contact the fixed power contacts mounted on the chassis plate of the switchboard module, even when the molded power contact kit is moved to shift the switchboard module from the service position to test position.
[0040] The interlock mechanism has a plunger fixed near the racking rod to obstruct the movement of the racking rod to prevent the movement of the switchboard module from the service position to test position, when the protective device is switched on. The interlock mechanism further comprises a gear wire attached to the plunger and to a protective device handle which is arranged on the switchboard module. The gear wire is moved to displace the plunger towards the racking rod to make the plunger to contact the racking rod to prevent the movement of the racking rod to stop the movement of the switchboard module from the service position to test position, when the protective device is switched on. The gear wire is moved to displace the plunger away from the racking rod to permit the rotation of the racking rod to move the switchboard module from the service position to test position, when the protective device is switched off. A pin is further
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provided on the racking rod to permit or to prevent the rotation of the racking rod. The gear wire is moved to displace the plunger towards the racking rod to make the plunger to contact the pin on the racking rod to prevent the rotation of the racking rod, when the protective device is switched on.
[0041] According to one embodiment of the present invention, the electrical contact system includes a fixed power contact mounted on a chassis plate. A molded power contact kit assembly is mounted on the chassis plate. The molded power contact kit is a main moving part which is racked in or out of the switchboard module using the racking rod attached to it to achieve the test position without opening the door of the switchboard panel.
[0042] According to one embodiment of the present invention, the compact molded power contact kit assembly includes a guiding rail. The guiding rail includes a fixed part and a moving part. The fixed part of guiding rail is mounted on a chassis assembly inside the switchboard. The molded power contact kit is mounted with a guide which is moved on the guide rail mounted on the chassis to move the molded power contact kit. The molded power contact kit includes a sliding jaw contact and an isolating jaw contact. The sliding jaw contact engages with the fixed contact terminal in the switchboard module and the isolating jaw contact is connected to a power supply dropper. The molded power contact kit is engaged with the racking rod through a racking-nut which is fixed at the bottom of the molded power contact kit. The power contacts are isolated by using the racking rod which can be rotated with the help of detachable racking handle in anticlockwise direction to bring the module from service to test position. A pin is
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provided on the racking rod and a plunger is fixed near the racking rod which prevents the rotation of racking rod when the protective device is switched ON. A gear wire is coupled between the protective device handle at one end and the plunger at the other end which allow the rotation of the racking rod only when the protective device is switched OFF.
[0043] FIG. 1 shows a top perspective view of the electrical contact system for switchboard modules according to one embodiment of the present invention. With respect to FIG. 1, the short circuit protective device in the switchboard module is enclosed in the switchboard panel 19. The electrical contact system of the switchboard module includes a fixed power contact 3 mounted on a chassis plate 1 inside the switchboard panel 19. The molded power contact kit is mounted on the chassis plate 1. The racking rod 2 is fixed below the chassis plate 1. The racking rod 2 is coupled to a racking nut provided at the bottom of the molded power contact kit.
[0044] The short circuit protective device handle 17 and the racking handle 14 connected to the racking rod 2 are accessible from the outer side of the switchboard panel 19. The racking handle is passed through a circular hole provided in the door of the switchboard module and connected to the racking handle. The power contacts are isolated by rotating the racking rod 2 with the help of detachable racking handle 14 in anticlockwise direction to bring the switchboard module from service to test position. The switchboard module can be switched ON and OFF by rotating the protective device handle 17. In order to interlock the electrical contacts in the switchboard module, the pin 18 is provided on the racking rod 2 and the plunger 15 is fixed near racking rod 2 which
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obstructs the rotation of racking rod 2 with the help of gear wire 16 coupled with the protective device handle 17. The pin 18 will only allow the rotation of the racking rod 2 when the protective device is switched OFF.
[0045] FIG. 2 shows a rear side perspective view of the electrical contact system for switchboard modules according to one embodiment of the present invention. With respect to FIG .2, the contact system includes a fixed power contact 3 mounted on a chassis plate land a dropper power contact 4. The molded power contact kit 5 is mounted on the chassis plate 1. A guiding rail 9 is fixed on the chassis plate land includes a C type groove to receive the movable guides 10 mounted at both the side ends of the molded power contact kit 5. The guiding rail 9 has a stopper 11 to restrict the movement of the molded power contact kit 5. The molded power contact kit 5 is provided with pluralities of sliding jaw contacts 8 and pluralities of isolating jaw contacts 7. The sliding jaw contacts 8 are in continuous contact with the fixed power contacts 3 while the isolating jaw contacts 7 make and break contacts with the dropper power contacts 4 in the switch board module, as the molded power contact kit 5 is moved due to the rotation of the racking rod 2.
[0046] The racking rod 2 is fixed below the chassis plate 1. The racking rod 2 engages with the racking nut provided at the bottom of the molded power contact kit 5. The molded power contact kit 5 is a main moving part which is racked in or out of the switchboard module to achieve the test position without opening the door of the switchboard panel. In order to operate the module from the service position to test position, a racking handle attached to the racking rod 2 is rotated in anticlockwise
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direction and the molded power contact kit 5 makes a reciprocating motion as it is engaged with racking rod 2 through racking nut 6, fixed at the bottom of molded power contact kit 5. The guiding rail 9 restricts the movement of molded power contact kit 5 in a fixed direction. A stopper 11 is provided in the fixed part of guiding rail 9 to restrict the moving part of guiding rail 10 to move by 30 mm only. The fixed power contacts 3 are fixed on the chassis plate 1. As the module is racked-out with the help of rack-in rod 2 the isolating jaw contact 7 of the molded power contact kit 5 isolates the power supply from the dropper power contacts 4. However the sliding jaw contacts 8 of molded power contact kit 5 always remain in contact with fixed power contact 3.
[0047] FIG. 3 shows a side view of the switchboard panel provided with an electrical contact mechanism according to one embodiment of the present invention. The electrical contact system is enclosed in the switchboard panel 19. In this position, the door 13 of the switchboard panel 19 is closed while the protecting device handle 17 and the racking handle 14 are arranged outside the door 13and are accessible from outside. The protecting device handle 17 are rotated to operate the switching device in ON and OFF position. The racking handle is inserted through a circular hole provided in the door and coupled to the racking rod. The racking handle 14 is rotated in anticlockwise direction to move the molded power contact kit to move the isolating jaw contacts away from the dropper power contact kits to disconnect the electrical power contacts in the switchboard module thereby moving the switchboard module to test position from the service position, when the protective device is switched off. The operator cannot rack-out the switchboard module when the short circuit protective device is switched ON. Hence the operator cannot operate the switchboard module in test position without switching OFF the
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protecting device. Once the module is brought to test position, the operator can safely do the maintenance or service operation.
[0048] FIG .4 shows a top side perspective view of the molded power contact kit provided in the electrical contact system for the switchboard modules according to one embodiment of the present invention. With respect to FIG. 4, the molded power contact kit 5 is mounted on a chassis plate 1 provided in the switchboard module. The molded power contact assembly includes a guiding rail a movable guide. The molded power contact kit is mounted on the fixed guiding rail 9 with a movable guide 10. The movable guide 10 is attached to both the ends of the molded power contact kit 5. The guiding rail 9 mounted on the chassis plate and near to the molded power contact kit 5. The guiding rail includes C type grooves to receive the movable guide attached to the molded power contact kit 5. The molded power contact kit is provided with pluralities of sliding jaw contacts 8 and pluralities of isolating jaw contacts 7. A racking nut is attached at the bottom of the molded power contact kit for engaging with a racking rod. When racking handle is rotated in anticlockwise direction, the molded power contact kit is moved within the switchboard module to make the isolating jaw contacts 7 of the molded power contact kit 5 to move away from the dropper power contacts thereby disconnecting the power supply through the dropper power contacts. However the sliding jaw contacts 8 of molded power contact kit 5 always remains in contact with the fixed power contacts 3 mounted on the chassis plate, even when the molded power contact kit 5 is moved. Thus the contact arrangements are used to isolate the power contacts in the switchboard modules to move the switchboard module to a test position from the service position even without opening the door of the switchboard panel.
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[0049] FIG. 5 shows a top side view of the molded power contact kit according to one embodiment of the present invention. With respect to FIG. 5, a racking nut 6 is fixed at the bottom of the molded power contact kit 5. A guiding rail 9 is mounted near the molded power contact kit 5 on the chassis plate provided in the switchboard module. A movable guide 10 is mounted on both the side ends of the molded power contact kit 5. The guiding rail 9 has a C type groove to receive the movable guide 10 attached to the molded power contact kit 5. The racking nut 6 is engaged with the racking rod so that the molded power contact kit 5 is moved along the guiding rails when the racking rod is rotated with a racking handle. When the racking rod 2 is rotated in anticlockwise direction, the molded power contact kit 5 is moved by a fixed distance to disconnect the power contacts from the droppers and the switchboard module is moved from the service to test position.
[0050] FIG. 6 shows a top view of the electrical contact system for switchboard module in service position according to one embodiment of the present invention. In service position, the sliding jaw contacts 8 in the electrical contact system engage with the fixed power contacts 3 in the switchboard module and the isolating jaw contacts 7 are connected to the power supply dropper contacts 14. The short circuit protective device is switched ON in service position. A pin is provided on the racking rod to prevent or permit the rotation of the racking rod. A plunger is provided near the racking rod to contact the pin to prevent the rotation of the racking rod. A gear wire 16 is connected between the protective device handle and the plunger. In the service position, since the protective device is switched ON, the gear wire 16 moves the plunger towards the
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racking rod so that the racking rod contacts the pin in the racking rod to prevent the rotation of the racking rod to avoid the movement of the switchboard module to the test position from the service position. Thus the interlock mechanism provided with a pin and a plunger arrangement prevents the operator from racking out the switchboard module when the short circuit protective device is switched ON. Hence the operator cannot change the switchboard module from service to test position without switching OFF the protecting device.
[0051] FIG. 7 shows a top view of the electrical contact system for a switchboard module in test position according to one embodiment of the present invention. With respect to FIG. 7, the isolating jaw contacts 7 in the molded power contact kit 5 are isolated from the dropper power contacts 4 in the switchboard module, when the switchboard module is moved from the service to test position. The switchboard module is racked out with the help of racking rod 2 to separate the isolating jaw contacts 7 of the molded power contact kit 5 from the dropper contacts 12. However the sliding jaw contacts 8 of molded power contact kit 5 always remain in contact with the fixed power contacts 3. In the test position, since the protective device is switched OFF, the gear wire 16 coupled with the protective device handle 17 moves the plunger away from the racking rod so that the plunger is not in contact with the pin of the racking rod thereby allowing the rotation of the racking rod to move the molded power contact kit 5 to disconnect the isolating jaw contacts 7 from the dropper power contacts 4 in the switchboard module.
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[0052] The molded power contact kit 5 is mounted on the chassis plate 1. The molded power contact kit 5 is a main moving part which is racked in or out of the switchboard module to achieve the test position without opening the door 13 of the switchboard panel 19. To move the switchboard module from service position to test position, the shutter is removed to insert the racking handle 14 to couple with the racking rod. Then the racking handle 14 is rotated in anticlockwise direction. As the racking rod is rotated with the help of the detachable racking handle 14 in anticlockwise direction and the molded power contact kit 5 is connected to the racking rod through the racking nut provided at the bottom of the molded power contact kit 5, the molded power contact kit 5 is moved along the guide rail 9 to make the sliding jaw contacts 8 to make and break contacts with the dropper power contacts 4. The guiding rail 9 restricts the movement of molded power contact kit 5 in a fixed direction. The stopper 11 is provided on the guiding rail 9 to restrict the movement of the molded power contact 5 by a distance of 30 mm.
[0053] FIG. 8a and 8b show a top view of the electrical contact system provided with an interlock mechanism in service and test positions according to one embodiment of the present invention. The interlock mechanism is provided to prevent the racking out of the switchboard module when the protective device is switched ON. The interlock mechanism has a plunger provided near the racking rod. A gear wire 16 is coupled with the protecting device handle at one end and with the plunger 15 at the other end. A pin 18 is provided on the racking rod 2 and the plunger is fixed near the racking rod 2. In service position, the plunger 15 is projected to contact the pin 18 on the racking rod 2 thereby preventing the rotation of racking rod 2. Thus the gear wire 16 coupled with the protective device handle prevents the rotation of the racking rod 2. The pin 18 will only
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allow the rotation when the protective device handle is switched OFF. Hence the operator cannot move the switchboard module to test position without switching OFF the protecting device.
[0054] FIG. 9 shows a side view of the racking handle 14 according to one embodiment of the present invention. The racking handle 14 in the electrical contact system is accessible from outside the switchboard panel. The racking handle 14 is inserted through a shutter provided in the door of the switchboard module to couple with the racking rod. The racking handle is rotated in anti-clockwise direction to disconnect the power contacts in the switchboard module. Thus the switchboard module is moved from the service position to test position without opening the door of the switchboard panel, when the protective device handle is switched off.
[0055] FIG. 10 shows a front view of the racking rod according to one embodiment of the present invention. With respect to FIG. 10, the pin 18 is provided on the racking rod to prevent the rotation of the racking rod to prevent the movement of the switchboard module to test position from the service position, when the protective device is switched ON. The plunger is moved away from the contact pin to permit the rotation of the racking rod to allow the movement of the switchboard module to test position, when the protective device is switched OFF.
G) ADVANTAGES OF THE INVENTION
[0056] The various embodiments of the present invention provide an electrical contact system to isolate the power contacts in the switchboard module and to operate the
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switchboard module from service to test position without opening the door of the switchboard panel. The contact system offers low contact resistance during racking in racking out of the switchboard modules, an interlock mechanism is provided to prevent the racking-out of the switchboard module when the short circuit protective device is switched ON. It ensures safety of the panel operator during maintenance or service process.
[0057] Although the invention is described with various specific embodiments, it will be obvious 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 the claims.

[0058] 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.
RAKESH PRABHU
Patent Agent
Date: 30th July, 2009. Place: Bangalore.
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CLAIMS
What is claimed is:
1. An electrical contact system for closed door test position of switch board modules
including fixed power contacts and dropper power contacts, the system
comprising:
a moulded power contact kit;
pluralities of sliding jaw contact installed in the moulded power contact kit;
pluralities of isolating jaw contacts arranged in the moulded power contact kit;
a guide attached to the moulded power contact kit;
a racking nut attached to the moulded power contact kit;
a racking rod coupled to the racking nut;
a racking handle attached to the racking rod; and
an interlock system;
wherein the racking rod is moved to bring a switch board module from a service
position to a test position without opening a door of the switchboard module.
2. The system according to claim 1, wherein the racking handle is rotated to move
the racking rod to move the moulded power contact kit to move the pluralities of
isolating jaw contacts from the respective dropper power contacts provided in the
switchboard module to move the switchboard module from the service position to
test position, without opening the door of the switchboard module.
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3. The system according to claim 1, wherein the interlock system prevents the movement of the switchboard module from the service position to test position without switching off a protective device.
4. The system according to claim 1, wherein the interlock system comprising a plunger fixed near the racking rod to obstruct the movement of the racking rod to prevent the movement of the switchboard module from the service position to test position, when the protective device is switched on.
5. The system according to claim 1, wherein the interlock system further comprises a gear wire attached to the plunger and to a protective device handle which is arranged on the switchboard module.
6. The system according to claim 1, wherein the gear wire is moved to displace the plunger towards the racking rod to make the plunger to contact the racking rod to prevent the movement of the racking rod to stop the movement of the switchboard module from the service position to test position, when the protective device is switched on.
7. The system according to claim 1, wherein the gear wire is moved to displace the plunger away from the racking rod to permit the rotation of the racking rod to move the switchboard module from the service position to test position, when the protective device is switched off.
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8. The system according to claim 1, further comprises a pin provided on the racking rod to permit or to prevent the rotation of the racking rod.
9. The system according to claim 1, wherein the gear wire is moved to displace the plunger towards the racking rod to make the plunger to contact the pin on the racking rod to prevent the rotation of the racking rod, when the protective device is switched on.
10. The system according to claim 1, wherein the molded power contact kit is
mounted on a chassis plate which is provided in the switchboard module.
11. The system according to claim 1, wherein the guide is attached to both the side surfaces of the molded power contact kit.
12. The system according to claim 1, wherein the guides are moved along the guide rails, that are mounted on the chassis plate of the switchboard module, to move the molded power contact kit to make the isolating jaw contacts to make and break contacts with the dropper power contacts.
13. The system according to claim 1, wherein the sliding jaw contacts are made to contact the fixed power contacts mounted on the chassis plate of the switchboard module, even when the molded power contact kit is moved to shift the switchboard module from the service position to test position.
14. The system according to claim 1, wherein the racking nut is attached to the bottom of the molded power contact kit.
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15. The system according to claim 1, wherein the racking handle is a detachable handle.
16. The system according to claim 1, wherein the racking handle is detachably attached to the racking rod.
17. The system according to claim 1, wherein the racking handle is detachably attached to the racking rod by inserting the racking handle through a shutter provided on the door of the switchboard module.
18. The system according to claim 1, wherein the racking handle is rotated in
anticlockwise direction to move the racking rod to move the molded power
contact kit to make the sliding jaw contacts to move away from the dropper power
contacts in the switch board module to move the switchboard module from the
service position to the test position, when the protective device is switched off.

RAKESH PRABHU Patent Agent,
ALMT Legal,
#2, Lavelle Road, Bangalore-560 001
To,
The Controller of Patents, The Patent Office, Mumbai
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