FORM 2
THE PATENTS ACT. 1970
(39 of 1970)
&
THE PATENTS RULES. 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
A LOCKING STRUCTURE FOR A CIRCUIT BREAKER;
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
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE PRESENT INVENTION
The present invention relates to a locking structure for switch devices, more particularly, to circuit breakers.
BACKGROUND AND PRIOR ART OF THE PRESENT INVENTION
A circuit breaker or a switchgear is an automatically/manually operated electrical switch responsible for making and carrying current under normal operating condition, and designed to protect an electrical circuit from overload or short circuit.
The circuit breaker is an absolutely essential device in the modern world, and one of the most important safety mechanisms in a building segment/industries/utilities. Whenever, electrical current in the wires arranged in the building segment/industries/utilities begins to flow beyond the designed value, the circuit breaker simply cut-off power till overload persists. Without the circuit breaker/protection device, electricity would be impractical because of the potential for fires and other mayhem resulting from simple wiring problems and equipment failures.
The circuit breaker can be resetted, either manually or automatically, to resume normal operation. Many of these circuit breakers include a switch knob movable between an 'On' and an 'Off position, hereinafter mentioned as a 'knob up' and a 'knob down' position. A rampart surrounds the switch knob between the 'knob up' and the 'knob down' positions define a switch knob cavity.
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Maintenance personnel or any concerned person, often use the circuit breaker to interrupt the flow of electrical energy through the circuit when the circuit, or electrical components connected thereto, require maintenance. The circuit breaker, however, is often remote from the location requiring maintenance. Therefore, it is desirable to a lock-out the circuit breaker to prevent an individual from inadvertently energizing the circuit while maintenance is being performed. Moreover, the switch knob cavity on the rampart that surround the switch knob have excessive clearance, which allows significant movement of the switch knob. For these reasons, it is desirable to provide such lock-out arrangement, which overcomes said problems.
There are known various types of casings and locking structures for the circuit breaker or the switchgear to lock-out the switch knob for security purpose, and to avoid any external hindrance to the operation of the circuit breaker for proper functioning of the system. The related casings and the locking structures disclosed hereinbelow mentioned patent applications.
JP Publication No. JP2000357445 discloses a circuit breaker storing casing comprises a casing body and a door body, and the door body is hinged with the casing body such that an opening in the casing body can be covered. A handle having a first keyway is provided on a side surface of the door body. In addition, the casing body is provided with a projection having a second keyway in the facing part of the first keyway. A circuit breaker is placed on the casing body of the circuit breaker storing casing, the opening in the casing body is covered by rotating the door body hinged to the casing body, and the first keyway provided in
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the handle is faced to the second keyway provided in the projection. A lock is inserted into the first and second keyways for locking. Thus, the keyways are not seen from the view of the front face of the circuit breaker storing casing not to lose a design property.
The aforesaid JP patent document discloses a casing for storing a circuit breaker. The casing body is covered by a rotating door body hinged to a casing body, such that the stored circuit breaker is not visual to a concerned person. Moreover, movement of a handle (similar to the knob), either up or down, provided on the circuit breaker is unsecured, resulting unauthorized person to move the knob.
U.S. Pat. No. 6,396,008 discloses a circuit breaker includes a housing; separable contacts; an operating mechanism having a movable operator handle with an OFF position and an ON position; and a handle lock device. The handle lock device includes: a member secured to the housing, a flange on the member disposed alongside the operator handle, an opening in the flange adapted to receive only one shackle and having a perimeter which includes first opposing portions adapted to receive a cross section of a safety lockout shackle and to restrain rotation of the shackle within the opening. The shackle blocks movement of the operator handle from the OFF to the ON position thereof. The perimeter also includes second opposing portions adapted to alternatively receive the different cross section of a shackle of a padlock with that shackle blocking movement of the operator handle from the OFF to the ON position thereof.
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The aforesaid US patent document discloses a casing or a housing provided on a circuit breaker, which can either be locked at 'ON' or 'OFF' position (similar to above mentioned 'knob up' and 'knob down' position), and provides excessive clearance that a knob shackled on the circuit breaker can be moved at closed position.
Moreover, other locking device in the known prior art lacks in safety measures and there is need for the locking device that take care of all safety measures. It is quite evident there is a room for improvement in the locking devices, which eliminates the drawbacks of prior-art solution.
SUMMARY OF THE PRESENT INVENTION
Accordingly, it is an object of the present invention to provide a locking structure
for a circuit breaker that avoids the disadvantages of the prior art.
More particularly, it is object of the present invention to provide the locking
structure for the circuit breaker that hide fastening arrangement, avoiding
accessibility to unauthorized individual.
It is another object of the present invention to provide the locking structure for the
circuit breaker eliminating clearance to provide restriction to movement of a knob
at closed position, without affecting tripping mechanism of the knob to protect an
electrical circuit from damage caused by overload or short circuit.
According to the present invention, the locking structure for the circuit breaker
includes a base plate with a cut portion having two opposite side walls each with
atleast one recess, said base plate attached to the circuit breaker by fastening
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means; a moving plate with a cut portion having two opposite side walls each with atleast one recess, said moving plate attached to the base plate; and a movable knob adapted to the circuit breaker receives the cut portion of the base plate, wherein the moving plate having plurality of extended portion to hide said fastening means, and to provide restriction to movement of the knob at closed position.
Other objects, feature and advantage of the invention will be apparent from the drawing, and from the detailed description that follows below.
BREIF DESCRIPTION OF THE DRAWINGS
To complement the description that is being given and in order to promote a
better understanding of the characteristics of the invention in accordance with a
practical embodiment of the same and as an integral part of the said description
a set of drawing accompany it in which, in an illustrative and non restrictive way,
the following are represented:
Figure 1 is a perspective view of the locking structure for the circuit breaker at
open position.
Figure 2 is a perspective view of the locking structure for the circuit breaker at
closed position, showing "the knob-down" position.
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DETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention provides a locking structure for a circuit breaker or a switchgear that hides fastening arrangement, avoiding accessibility to unauthorized individual.
According to one embodiment, the locking structure for the circuit breaker of the present invention is shown in figure 1 as (100).
The locking structure (100) for the circuit breaker (200) comprises two essential elements, a base plate (110) and a moving plate (120). The base plate (110) with a cut portion (111), having a pair of opposite side walls (112) with atleast one hole (113) each. The base plate (110) attached to the circuit breaker (200) by fastening means (130). The moving plate (120) with a cut portion (121), having a pair of side walls (122) with atleast one hole (123) each. The moving plate (120) hinged to the base plate (110) by riveting thereby allowing only one degree of freedom. The cut portion (111) of the base plate (110) receives a movable knob (210) of the circuit breaker (200) when fastened by fastening means (130). The cut portion (121) of the moving plate (120) receives a movable knob (210), whenever the moving plate (120) is closed or locked over the base plate (110). The movable knob (210) can move either 'up', hereinafter mentioned as 'a knob-up' position, or 'down', hereinafter mentioned as 'a knob-down' position. Referring to figure 2 and figure 1 as well, the base plate (110) is attached to the circuit breaker (200) by fastening means (130). The fastening means (130) is a mounting screw, a rivet or the like. The fastening means (130) are clearly visible, which is accessible to any individual, either concerned individual or unauthorized
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individual. To avoid accessibility of the fastening means (130), to either to concerned individual or to unauthorized individual, the moving plate (120) hinged to the base plate (110) by riveting is provided by plurality of extended portion (124) (the hinged attachment is generally shown by reference numeral (140), in figure 2). The plurality of extended portion (124) is provided on the front and on the both opposite sides of the moving plate (120). The hinged moving plate (120), whenever is closed, either in 'the knob-up' (not shown) on in 'the knob-down' position (220), covers the entire said fastening means (130) fastened on the base plate (110). The purpose of covering the fastening means (130) is to avoid the unauthorized individual to simply plug-out the locking structure (100) by opening the fastening means (130) by a fastener.
The hinged moving plate (120), either closed in the 'knob-up' on in the 'knob-down' position (220), the hole (123) provided on the sidewalls (122) concentrically meets the hole (113) provided on the sidewalls (112). The concentrically meeting holes (113) and (123) (shown by reference numeral 150) provided on the sidewalls (112) and (122), of the base plate and the moving plate respectively, receives a locking device. The concentrically meeting holes (113) and (123) ^ceives the locking device and is lockable in 'the knob-up' and in 'the knob-down' position thereby restricting the knob movement either to 'knob up' or knob down' position by unauthorized individual. The concentrically meeting holes (113) and (123), receiving the locking device provides restriction to the movement of the knob. The locking device that is being locked after receiving concentric holes (113) and (123) provides restriction to unauthorized individual,
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or concerned individual like a maintenance officer or a mender to move the knob 'up' or to move 'down'. At the sametime, the concerned individual like the maintenance officer or the mender can access by unlocking the locking device. The concentrically meeting hole (113) and (123) receiving the locking device, lockable in 'the knob-up' and in 'the knob-down' position, trips the knob without affecting the tripping mechanism at overload or short circuit conditions, isolating a defective part from unaffected part. The hole (123) provides zero clearance to the knob, avoiding movement at closed position.
The locking structure (100) is tamperproof and tease proof, structured to be assembled or mounted, on a single knob circuit breaker and on a multi knob circuit breaker. The locking structure (100) can be assembled in standard door cut out of same size as of the locking structure. The locking structure (100) is consumer friendly for key lock mechanical interlocking and can be installed on the site as per convenience of user. Moreover, the locking structure (100) is easy to manufacture, and adds to the functioning of the circuit breaker (200) or the switchgear in terms of reliability, safety and protection.
The forgoing description of the invention has been described for purpose of clarity and understanding. It is not intended to limit the invention to the precise from disclosed. Various modifications may be possible within the scope and equivalence of the appended claims.
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WE CLAIM
1. A locking structure for a circuit breaker, comprising:
a base plate with a cut portion, having two side walls with atleast one hole each,
said base plate attached to the circuit breaker by a fastening means; and
a moving plate with a cut portion, having two side walls with atleast one hole
each, said moving plate attached to the base plate,
wherein the cut portion of the base plate receives a movable knob of the circuit
breaker, and the moving plate having plurality of extended portion, which covers
said fastening means and provides restriction to movement of the knob.
2. The locking structure for the circuit breaker as claimed in claim 1, wherein the hole provided on the side walls of the base plate and the moving plate concentrically meets, and receives a locking device at closed position.
3. The locking structure for the circuit breaker as claimed in claim 1, wherein the fastening means is mounting screw or riveting.
4. The locking structure for the circuit breaker as claimed in claim 1, wherein the moving plate is hinged to the base plate by riveting allowing one degree of freedom.
5. The locking structure for the circuit breaker as claimed in claim 1, wherein the locking structure is lockable in "the knob-up" position.

6. The locking structure for the circuit breaker as claimed in claim 1, wherein the locking structure is lockable in "the knob-down" position.
7. The locking structure for the circuit breaker as claimed in claim 1, wherein the knob is unmoved up or down, at closed position/locked position.
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8. The locking structure for the circuit breaker as claimed in claim 1, wherein the sidewalls are opposite to each other.
9. The locking structure for the circuit breaker as claimed in claim 1, wherein the locking structure is mounted over single knob circuit breaker.
10. The locking structure for the circuit breaker as claimed in claim 1, wherein the
locking structure is mounted over multi knob circuit breaker.
Dated this 29th day of March, 2007

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ABSTRACT
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A locking structure (100) for a circuit breaker (200), comprising a base plate (110) with a cut portion (111), having a pair of opposite side walls (112) with atleast one hole (113) each, said base plate (110) attached to the circuit breaker (200) by fastening means (130); a moving plate (120) with a cut portion (121), having a pair of opposite side walls (122) with atleast one hole (123) each, said moving plate (120) attached to the base plate (110), wherein the cut portion (111) of the base plate (110) receives a movable knob (210) of the circuit breaker (200), and the moving plate (120) having plurality of extended portion (124), which covers said fastening means (130), and provides restriction to movement of the knob (210).
Reference figure 1