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:
SAFETY SHUTTER ASSEMBLY FOR DRAW OUT TYPE CIRCUIT BREAKER WITH SINGLE POINT ACTUATION
APPLICANT:
LARSEN & TOUBRO LIMITED
I.&T House, Ballard Estate, P.O. Box No. 278,
Mumbai, 400 00], 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 circuit breakers and particularly to safety shutter device for draw out type circuit breakers,
B) BACKGROUND OF THE INVENTION
[0002] The circuit breakers protect electrical circuit from overload and short circuit damages. The circuit breakers are used for main power distribution in large industrial plants. The cradle assemblies connected to main power are used to enclose heavy and large circuit breakers. Mechanical racking mechanisms are provided in the cradle assembly which can be operated manually or by using motors. The circuit breakers are provided with complimentary draw-out construction for easy installation and separation from the cradle assembly without disturbing main power connections.
100031 The circuit breakers can be tested and serviced by mechanically moving it away from the cradle terminals coupled to the main power circuit. The complete isolation of the main power has to be achieved to ensure safety of the personnel during maintenance. Hxtreme caution has to be adopted to ensure complete isolation during maintenance for preventing any inadvertent lapse in safety mechanism.
[0004] The currently available safety shutters has complex operating lever arrangements with two point actuation mechanisms to engage and disengage circuit

breakers. The actuating mechanisms are placed at extreme right and extreme left of safety shutters to open or close the safety shutters. Under such circumstances manual intervention required in open and close of safety shutters causes imprecise alignment of opening and closing of the safety shutters to actuate the shutters. Further, time is consumed for installation, maintenance and assembling of multiple shutters, furthermore, installation of the safety shutters is complex and requires precise alignment of openings to actuate the shutters. The cost of assembling and maintaining a complex operating lever and actuating mechanism is substantially high. Hence there is a need to provide a simple shutter operating and actuating mechanism at reduced cost.
[0005] The currently available safety mechanisms adopt complex mechanical arrangements to provide the required safety to the maintenance personnel. In light of foregoing discussion there is a need to provide a shutter assembly with a simple mechanism to open and close the safety shutters.
|0006] 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
|0007] The primary object of the present invention is to provide a safety shutter assembly with a single point actuation for a draw-out type circuit breaker to open and close the safety shutters during the insertion and withdrawal of the circuit breakers,

[0008] Another object of the present invention is to provide a safety shutter assembly with single actuation point for self actuation of the shutter doors for draw out type circuit breakers.
[ 00091 Yet another object of the present invention is to provide a safety shutter assembly for individual current carrying pole assembly capable of interrupting the main circuit,
[0010] 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
[0011] The various embodiments of the present invention provide a a safety shutter assembly with a single point actuation for a draw-out type circuit breaker to open and close the safety shutters during the insertion and withdrawal of the circuit breakers. The safety shutter assembly has single actuation point for the self actuation of the shutter doors.
|0012] According to ont embodiment of the present invention, the safety shutter assembly has a basic supporting structure provided with several grooves. Pluralities of movable shutter doors are siidably mounted on the grooves. An actuating slider is connected to the shutter doors. An orthogonal slider is connected to the actuating slider. The actuating slider is pushed to open the movable shutter doors, when the breaker is inserted into the cradle assembly.


[0013] The actuating slider is pushed by the breaker terminal to move the orthogonal slider and to move the shutter doors between the grooves to open the shutter doors, when the breaker is mounted on the cradle assembly. The actuating slider is moved outwardly to close the shutter doors, when the breaker is removed from the cradle assembly. A first spring mechanism is connected with the actuating slider. The first spring is activated to push the actuating slider outwardly to close the shutter doors, when the breaker terminal is inserted into the cradle assembly. A second spring mechanism is connected to the orthogonal slider. The movable shutter doors are coupled lo the actuating slider through the orthogonal slider. The actuating slider is pushed in move the orthogonal slider to move the shutter doors in the grooves.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0014] 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:
[0015] FIG. I illustrates a side perspective view of a cradle assembly mounted with a safety shutter assembly according to one embodiment of the present invention.
[0016] FIG. 2 illustrates a front view of shutter doors of a shutter assembly in close condition according to one embodiment of the present invention.
[0017] FIG. 3 illustrates a front view of shutter doors of a shutter assembly in open condition according to one embodiment of the present invention.

[0018] FIG. 4 illustrates a side view of a shutter assembly according to one embodiment of the present invention.
|0019] FIG. 5 illustrates a sectional view of breaker terminal at initial condition of self actuation mechanism with respect to shutter according to one embodiment of the present invention.
[0020] FIG. 6 illustrates a sectional view of breaker terminal at final position according to one embodiment of the present invention,
[0021] 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
[0022] 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.

[0023] The various embodiments of the present invention provide a safety shutter assembly with a single point actuation for a draw-out type circuit breaker to open and close the safely shutters during the insertion and withdrawal of the circuit breakers. The safety shutter assembly has single actuation point for the self actuation of the shutter doors.
[0024] According to one embodiment of the present invention, the safety shutter assembly has a basic supporting structure provided with several grooves. Pluralities of movable shutter doors are slidably mounted on the grooves. An actuating slider is connected to the shutter doors. An orthogonal slider is connected to the actuating slider. The actuating slider is pushed to open the movable shutter doors, when the breaker is inserted into the cradle assembly.
[0025] The actuating slider is pushed by the breaker terminal to move the orthogonal slider and to move the shutter doors between the grooves to open the shutter doors, when the breaker is mounted on the cradle assembly. The actuating slider is moved outwardly to close the shutter doors, when the breaker is removed from the cradle assembly. A first spring mechanism is connected with the actuating slider. The first spring is activated to push the actuating slider outwardly to close the shutter doors, when the breaker terminal is inserted into the cradle assembly. A second spring mechanism is connected to the orthogonal slider. The movable shutter doors are coupled to the actuating slider through the orthogonal slider. The actuating slider is pushed in move the orthogonal slider to move the shutter doors in the grooves.


[0026] According to one embodiment of the present invention, a shutter assembly is provided between a breaker terminal and a cradle terminal coupled to main power source. A shutter assembly is provided for each pole in a breaker pole assembly. The shutter assembly has self-actuating shutter doors to isolate main power supply, when the breaker assembly is disengaged from the cradle assembly. The shutter assembly includes an actuating slider with movable shutter doors. The actuating slider of the shutter assembly acts as single actuation point for self-actuation of the shutter doors.
|0027] A draw out type circuit breaker has a breaker unit mounted on a cradle assembly. The breaker unil has current carrying pole assembly for interrupting the main circuit. A rack-in mechanism is provided on the cradle assembly to engage or disengage the breaker unit from the cradle assembly during maintenance or inspection operation. The breaker unit rests on parallel rails sliding inside the grooves associated with the side plates in parallel. The rails slide by means of rack mechanism resting on base plate. When the circuit breaker is disengaged from cradle assembly, live current carrying part of the main circuit must be isolated via the safety shutter to prevent a mishap to the operating personnel during maintenance. The safety shutter must be kept open, when the breaker is engaged into the cradle assembly.
[0028] The cradle assembly has a cradle support mounted between two cross pieces that are connected to the side plates in parallel. The cradle terminal with jaw units is mounted on the side plates. The circuit breaker has a pole assembly to interrupt the main circuit. A breaker terminal is connected to the poles. When the breaker is

engaged to the cradle assembly, the jaw units are inserted into breaker terminal to complete the main circuit.
|0029] A safety shutter assembly is fixed on the two parallel cross pieces through screws. The safely shutter assembly is installed on the draw out type circuit breaker using a simple operation. The shutter assembly has a base support mounted on two cross pieces which are connected in parallel between the two side plates of a cradle assembly in a circuit breaker. The base support has several grooves inside which the shutter doors slides.
[0030] The shutter assembly has an single point actuating mechanism comprising two movable shutter doors mounted on the base support so that the shutter doors are moved orthogonally to permit the entry of a breaker terminal in the circuit breaker, when the circuit breaker is inserted into the cradle. Several grooves are provided on the base support to receive (he movable shutter doors.
[0031] A spring is provided on the base support and connected to movable shutter doors so that one end of the spring is connected to the movable door while the other end is fixed rigidly inside the grooves provided at the side edges of the base support. The live current carrying part of the main circuit is isolated through the safety shutter assembly to prevent the occurrence of shock or mishap to the operating personnel, when the circuit breaker is disengaged from the cradle assembly. The shutter doors are kept opened, when the breaker is engaged into the cradle assembly,
31 MAR 2009

[0032] When a basic breaker is inserted into the cradle, the breaker terminal pushes the actuating slider which slides between parallel rests in turn pushes movable shutter doors orthogonally to provide an opening to permit the entry of the breaker terminal. The surface of the breaker terminal is made to contact the inner surfaces of the shutter doors. As the breaker terminal is further moved inside, the shutter doors are moved inside the grooves and the springs are compressed. In the final position, the movable shutter door rests on the surfaces of the breaker terminal. Thus the breaker terminal is passed through the opening between the shutter doors to contact the cradle terminal to complete an electrical circuit.
[0033] When the breaker is disengaged from the cradle assembly, the breaker terminal is moved out of the shutter assembly. The spring pushes the movable doors forward to close the doors thereby ensuring the safety of the operating personnel.
[0034] FIG. I illustrates a side perspective view of a cradle assembly mounted with a safety shutter assembly according to one embodiment of the present invention. With respect to FICi. 1. cradle assembly I has base plate to support circuit breaker 2 and safety shutter 3 and side plates. The circuit breaker rests on parallel rails. The guide rails are used to move breakers inside the cradle assembly. A racking in mechanism is provided on base plate to move the guide rails inside the cradle. The side plates are supported by top cross piece 4 and bottom cross piece 5. Both the bottom cross piece 5 and the top cross piece 4 arc arranged in parallel. A cradle support is mounted on the cross pieces 4, 5. Safety shutter assembly 3 is mounted between top and bottom cross pieces 4 and 5 to provide safety to maintenance personnel during work. The

shutter assembly 3 is mounted on cross piece 4 and 5 using screws. The shutter assembly 3 includes an actuating slider 13 with movable shutter doors. When the breaker is inserted into the cradle, the breaker terminal pushes the actuating slider 13 to open the shutter doors.
|()035] FIG. 2 illustrates a front view of shutter doors of a shutter assembly in close condition according to one embodiment of the present invention. The safety shutter assembly is mounted on a basic supporting structure 10. The shutter assembly includes an actuating slider 13 with movable shutter door 11 and movable shutter door 12. When the breaker is inserted into the cradle, the breaker terminal pushes the actuating slider 13 to open the shutter doors, When the breaker terminal is engaged to the cradle terminal through a jaw unit, the breaker unit also moves forward pushing actuating slider 13 which in turn moves orthogonal sliders 14 which results in opening of the shutter doors attached to the sliders,
[0036] FIG. 3 illustrates a front view of shutter doors of a shutter assembly in open condition according to one embodiment of the present invention. The safety shutter assembly is mounted on a basic supporting structure 10. The shutter assembly includes an actuating slider 13 with movable shutter door \\ and movable shutter door 12. When the breaker terminal is engaged to the cradle terminal through a jaw unit, the breaker unit also moves forward pushing actuating slider 13 which in turn moves orthogonal sliders 14 which results in opening of the shutter doors attached to the sliders. The movable shutter doors slide along with the orthogonal sliderl4, since


the protruding part 11A and I2A of moving shutters are engaged into slot 14A of orthogonal slider 14, causing the shutter doors to open and close accordingly,
[0037] FIG. 4 illustrates a side view of a shutter assembly according to one embodiment of the present invention. The safety shutter assembly is mounted on a basic supporting structure 10, The supporting structure has several grooves 16. The shutter assembly includes an actuating slider 13 with movable shutter door 11 and movable shutter door 12.plurality of protruding grooves 16 are provided orthogonal to the shutter doors 11 and 12. The movable shutter doors 11 and 12 slides inside the grooves 16. When the breaker terminal is engaged to the cradle terminal through a jaw unit, the breaker unit also moves forward pushing actuating slider 13, which slides between parallel rests 17, which in turn moves orthogonal sliders 14 which results in opening of the shutter doors attached to the sliders.
[0038] FIG- 5 illustrates a sectional view of breaker terminal at initial condition of self actuation mechanism with respect to shutter according to one embodiment of the present invention. The sectional view has the actuating slider 13 and the orthogonal slider 14. a spring 21 is associated with the orthogonal slider 14 and a spring 20 is associated with the actuating slider 13. When the breaker terminal is engaged to the cradle terminal through a jaw unit, the breaker unit also moves forward pushing actuating slider 13, which in turn moves orthogonal sliders 14. When the actuating slider 13 is pushed forward the surface 19 associated with the actuating slider 13 comes in contact with surface 18 associated with the orthogonal slider 14 pushing it orthogonally.


[0039] PIG. 6 illustrates a sectional view of breaker terminal at final position according to one embodiment of the present invention. The sectional view has the actuating slider 13 and the orthogonal slider 14. a spring 21 is associated with the orthogonal slider 14 and a spring 20 is associated with the actuating slider 13. When the breaker terminal is engaged to the cradle terminal through a jaw unit, the breaker unit also moves forward pushing actuating slider 13, which in turn moves orthogonal sliders 14. When the actuating slider 13 is pushed forward the surface 19 associated with the actuating slider 13 uomes in contact with surface 18 associated with the orthogonal slider 14 pushing it orthogonally. Further when the actuating slider 13 is pushed the orthogonal slider 14 moves outward due to profile 19 associated with the actuating slider 13 and rests on surface 23 associated with the actuating slider 13. The spring 21 rests between the orthogonal slider and the surface 23. Due to outward movement of the orthogonal slider 14 the orthogonal slider 14 presses the spring 21, which brings the orthogonal slider to the initial position when the breaker unit is racked out for maintenance. During the rack out mechanism the actuating slider 13 comes to initial position due to spring 20.
G) ADVANTAGES OF THE INVENTION
[0040] Thus the various embodiments of the present invention provide a safety shutter assembly for draw out type circuit breakers for easy installation and separation from the cradle assembly without disturbing main power connections. The shutter doors are provided on the safety shutter assembly to isolate the main power supply when a

circuit breaker is moved to the maintenance position. The safety shutter assembly has an actuating slider which acts as a single point actuation point for closing and opening of the shutter doors. I'he single actuation point mechanism helps in the precise alignment of the shutter doors during making and braking of the circuit breaker unit. The shutter doors are moved orthogonally to provide an opening for the passage of the breaker terminals, when the breaker terminals are inserted to contact the cradle terminals to complete the main circuit. The shutters doors are closed to cut off the main circuit to provide safety to the operating personnel,
[0041] 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,

[0042] 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: March 30, 2009. Place: Bangalore-

CLAIMS
What is claimed is:
1. A safety shutter assembly for draw out type circuit breaker mounted on a
cradle assembly comprising:
a basic supporting structure;
pluralities of grooves provided on the basic supporting structure;
pluralities of movable shutter doors slidably mounted on the grooves;
an actuating slider connected to shutter doors; and
an orthogonal slider connected to the actuating slider;
wherein the actuating slider is pushed to open the movable shutter doors,
when the breaker is inserted into the cradle assembly.
2. The assembly according to claim 1, wherein the actuating slider is pushed by the breaker terminal to move the orthogonal slider to move the shutter doors between the grooves to open the shutter doors, when the breaker is mounted on the cradle assembly.
3. The assembly according to claim I, wherein the actuating slider is moved outwardly to close the shutter doors, when the breaker is removed from the cradle assembly,
4. The assembly according to claim 1, further comprises first spring mechanism connected with the actuating slider.


5. The assembly according to claim 4, wherein the first spring is activated to push the actuating slider outwardly to close the shutter doors, when the breaker terminal is inserted into the cradle assembly.
6. The assembly according to claim 1, further comprising a second spring mechanism connected to the orthogonal slider.
7. The assembly according to claim 1, wherein the movable shutter doors are coupled to the actuating slider through the orthogonal slider,
S. The assembly according to claim 1, wherein the actuating slider is pushed in move the orthogonal slider to move the shutter doors in the grooves.
Dated this the 30th day of March 2009
RAKESH PRABHU Patent Agent,
ALMT Legal,
#2. Lavelle Road, Bangalore-560 001
To.
The Controller of" Patents,
The Patent Office, Mumbai