FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
Padlock Assembly for Circuit Breaker
2. APPLICANT:
(a) NAME: Larsen&Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: LARSEN&TOUBRO LIMITED,
L&T House, Ballard Estate, P. 0. Box: 278, Mumbai400 001,India
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Padlock Assembly for Circuit Breaker
Field of the invention
The present invention relates generally relates to a padlock assembly for circuit breaker, and more particularly, to the padlock assembly for preventing unwanted racking operation of the circuit breaker.
Background of the invention
Generally, draw out type circuit breaker includes two units i.e. a cradle and a breaker. The cradle is fixed with a panel and the breaker unit is mounted on guiding rail of the cradle. The circuit breaker has three distinct positions, for example, service, test and isolation. When both power contacts and auxiliary contacts are engaged, the position of the circuit breaker is called as 'service' position. Further, when the power contacts are engaged and the auxiliary contacts are disengaged, then the position is called as 'Test' position. When both the power contacts and the auxiliary contacts are disengaged, the position of the circuit breaker is called as 'Isolation' position. These three distinct positions/ conditions of the circuit breaker are achieved by using a racking mechanism of the cradle unit. The cradle mechanism has to be operated to achieve service, test, and isolation position.
Figures la and lb show a draw-out type circuit breaker. The draw-out circuit breaker includes two units, for example, a cradle assembly unit (200) and breaker unit (150). The cradle assembly unit (200) is rigidly fixed with a panel (not shown). The cradle assembly (200) includes a cradle terminal (not numbered), a

guiding rail (180) and a circuit breaker racking mechanism (130). The cradle terminal is used to terminate external links for taking supply. The circuit breaker (150) unit is mounted on the guiding rail (180). For achieving service, test, isolation position of the circuit breaker (150), the racking mechanism (130) is used. By preventing rotation of a racking screw (10), the racking operation of the circuit breaker (150) can be stopped. To ensure the unwanted operation of the circuit breaker at any position (service, test and isolation), padlocking feature is required as an inherent accessory,
In current draw out type circuit breakers, padlocking feature is provided on the pane], where the circuit breaker is mounted. Padlocking is not a part of the circuit breaker unit. For operating the circuit breaker, cut-outs are provided on the panel door for accessing circuit breaker mechanism and the cradle racking mechanism through a circuit breaker fascia and a cradle fascia respectively. The padlocking feature is provided on the door of the panel by blocking the cradle fascia cut-out of the door. If the cut-out of the door is blocked, then the cradle racking mechanism is not accessible from the outside. As the cradle padlocking arrangement is not a part of the circuit breaker, the cradle racking mechanism can be easily defeated by opening the door of the panel. The door of the panel can be opened easily by rotating the cam lock of the door. So, in open door condition, the circuit breaker racking operation can be done.
Accordingly, there exists a need to provide a padlocking mechanism which does not allow operating the racking mechanism once padlocking is done, at both closed and open door condition.

Objects of the invention
An object of the present invention is to provide padlocking of the circuit breaker at every distinct position such as service, test and isolation.
Another object of the present invention is to prevent unwanted racking operation of the circuit breaker.
Summary of the invention
Accordingly, the present invention provides a padlock assembly for circuit breaker. The breaker unit is mounted on guiding rail of a cradle assembly, and the cradle assembly fixed within a panel. Further, the padlock assembly is mounted on a cradle interlock plate of the cradle assembly. The padlock assembly includes a racking screw for changing position of the circuit breaker to any one of service, test and isolation, a stopper mounted on the racking screw and capable of rotating along with the racking screw, and a curved pin member configured to pass through the cradle interlock plate. The curved pin member is capable of removably engaging with the stopper. The assembly further includes a spring coupled with the curved pin member above the cradle interlock plate and a split pin coupled to the curved pin member down the cradle interlock plate, wherein split pin and the spring maintains disengagement of the curved pin member with the stopper in normal condition.
The assembly furthermore includes a cover member secured to the curved pin member. The cover member is capable of being accessed from outside of the panel

through a cradle fascia. The cover member includes slots configured thereon for securing padlocks thereto. Wherein, upon pulling the cover member from inside the cradle fascia and securing padlock thereto, the curved pin member gets pulled in front from the cradle interlock plate as the spring gets compressed, and when the racking screw is rotated, the curved pin member hinders the rotation of the stopper thereby hindering the racking operation-Brief description of the drawings
Figures la and lb shows a draw-out type circuit breaker assembly of the prior art at normal operating condition;
Figures 2a and 2b show a perspective view of a padlock assembly, in accordance with the present invention;
Figures 3a-3f shows various components of the padlock assembly of figure 2;
Figure 4a shows a perspective view of the padlock assembly of the present invention in normal operating condition;
Figure 4b shows a cross-sectional view of the padlock assembly of the present invention in normal operating condition;
Figure 5a shows a perspective view of the padlock assembly of the present invention in padlock condition; and

Figure 5b shows a cross-sectional view of the padlock assembly of the present invention in padlock condition.
List of the Parts

Part No. Name
10 racking screw
20 stopper
30 curved pin member
32 ring
40 spring
50 split pin
60 cover member
62 slots
70 the cradle interlock plate
80 cradle fascia
90 padlocks
Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.

The present invention provides a padlock assembly for circuit breaker. The padlock assembly provides padlocking of the circuit breaker at every position such as service, test and isolation, Further, the present invention prevents unwanted racking operation of the circuit breaker.
Referring to figure 2 to 5b, a padlock assembly for circuit breaker and components thereof are shown, in accordance with the present invention. Specifically, figure 2 shows the padlock assembly [100]. The padlock assembly (100) includes a racking screw (10], a stopper (20), a curved pin member (30), a spring (40), a split pin (SO), and a cover member {60).
The racking screw (10) as shown in figure 3c is used for changing position of the circuit breaker to any one of service, test and isolation position. The stopper (20) (figure 3e) is mounted on the racking screw (10). The stopper (20) is capable of rotating along with the racking screw (20) when the racking screw (20) is rotated. The stopper (20) removably engages with the curved pin member (30).
Specifically, the curved pin member (30) as shown in figure 3b is configured to pass through the cradle interlock plate (70). The curved pin member (30) is capable of removably engaging with the stopper (20) and hinders the rotating
motion thereof.
The curved pin member (30) includes a spring (40) (figure 3d) coupled thereto past the cradle interlock plate (70). The curved pin member (30) furthermore includes two split pins (50) coupled thereto before the cradle interlock plate (70)

and after the spring [40). The split pin (50) past the cradle interlock plate (70) and the spring (40) beyond the cradle interlock plate (70) maintain disengagement of the curved pin member (30) with the stopper (20) in normal operating condition. The curved pin member (30) includes a cover member (60) as shown in 3a (1) and 3a (2) secured at outer end thereof.
The cover member (60) is capable of being accessed from outside of the panel (not shown) through a cradle fascia (80). The cover member (60) includes slots (62) configured thereon for securing padlocks (90) thereto. In an embodiment, the cover member (60) is press fitted with the outer end portion of the curved pin member (30). For press fitting the cover member (60) with the curved pin member (30), one groove (64) has been provided inside the cover member as shown in figure 3a and a ring (32) is provided on the counterpart of the curved pin member (30). During, normal operating condition, the cover member (60) is inside the cradle fascia (80).
As shown in figure 4a and 4b, during normal operating condition i.e. without padlocking, the cover member (60) is inside the cradle fascia (80). The split pin (50) and the spring (40) maintain the position of the curved pin member (30) such that the stopper (20) is free to rotate along with of the racking screw (20). So, the racking operation is possible at that time.
For padlocking the circuit breaker as shown in figure 5a and 5b, the cover member (60) inside cradle fascia (80) needs to be pulled to the front manually. As the cover member (60) moves in the front direction through the cradle fascia (80), the

spring (40) gets compressed against the cradle interlock plate (70) and the curved pin member (30) also moves in front direction from the cradle interlock plate (70). At this condition, if the racking screw (10) is rotated, the stopper (20) hits/engages with the curved pin member (30) which is already pulled towards outer direction and hinders the rotation of the stopper (20) and in turn hinders rotation of racking screw (10). Hence, the racking operation is not possible. As the cover member (60) moves outside the cradle fascia (80), the slots (62) on the cover member (60) are exposed and padlocks (90) can be mounted on the slot (62). In an embodiment, multiple padlocks of different diameter can be put on the cover member (60). Once padlock (90) is inserted on the cover member (60), the cover member (60) cannot move back side, and stays at that position. This padlocking of circuit breaker can be done at any position of the breaker i.e. Service, Test, and Isolate.
As the multiple padlocks are provided for the circuit breaker, it ensures proper co-ordination between all the functional units of the industry. The racking operation of the circuit breaker is only possible, if all the padlocks (90) are removed from the cover member (60). When the padlock (90) are removed from the cover member (60), the compressed spring (40) releases its energy and brings back the curved pin member (30) to its normal condition. Thereafter, the stopper (20) of the racking screw (10) clears/disengages the curved pin member (30) and the racking operation is possible. As shown in figure 4a and 4b.
The padlocking of the circuit breaker ensures the unwanted racking operation of the circuit breaker at both closed and open door condition.

Advantages of the invention
1. The padlock assembly (100) does not allow operator to operate racking mechanism of the circuit breaker once the padlocking has been done to the cradle.
2. The padlock assembly (100) ensures the safety of the operator by preventing unwanted operation of the circuit breaker.
3. The padlock assembly (100) uses multiple lock which ensures proper co-ordination of the different functional unit of the industries. Circuit breaker can be operated only when, all the locks are removed from the padlock component.
4. The padlock assembly (100) can be used to padlock the circuit breaker at any position i.e. service, test or isolation.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description, They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We Claim:
1. A padlock assembly [100] for circuit breaker, the circuit breaker mounted on guiding rail of a cradle assembly, and the cradle assembly fixed within a panel the padlock assembly [100] mounted on a cradle interlock plate [70) of the cradle assembly, the padlock assembly comprising:
a racking screw (10) for changing position of the circuit breaker to any one of service, test and isolation;
a stopper (20) mounted on the racking screw and capable of rotating along with the racking screw [10),
a curved pin member {30} configured to pass through the cradle interlock plate (70), the curved pin member (30) capable of removably engaging with the stopper (20);
a spring (40) coupled with the curved pin member (30) past the cradle interlock plate (70),
two split pins (50) coupled to the curved pin member (30) before the cradle interlock plate(70), the split pins (50) and the spring maintaining disengagement of the curved pin member (30) with the stopper (20) in normal condition; and
a cover member (60) secured to the curved pin member (30), the cover member (60) capable of being accessed from outside of the panel through a cradle fascia (80), the cover member [60) having slots (62) configured thereon for securing padlocks (90) thereto,
wherein, upon pulling the cover member (60) from inside the cradle fascia (80) and securing padlocks (90) thereto, the curved pin member (30) gets pulled in front from the cradle interlock plate (70) as the spring (40) gets

compressed, and when the racking screw (10) is rotated, the curved pin member (30) hinders the rotation of the stopper (20) thereby hindering the racking operation.
2. The padlock assembly as claimed in claim 1, wherein the cover member has multiple slots (62) to accommodate multiple padlocks (90).