FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention: INTEGRATED SAFETY SWITCH ASSEMBLY FOR
OPERATIONAL SAFETY IN CIRCUIT BREAKERS
2. Applicant(s):
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L & T House, Ballard Estate, Mumbai 400 001, State
of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to circuit breakers. More particularly the present invention relates to an integrated safety switch assembly for operational safety in circuit breakers providing status indication for manual charging and electrical cut-off.
BACKGROUND AND THE PRIOR ART
An electrical circuit breaker may be defined as a unit designed to carry, make & break current and protect the equipments connected in the electrical circuit from abnormal conditions like overload, under-voltage or short circuit etc. A circuit breaker is commonly used as an electrical switching device.
Circuit breakers are equipped with springs that are compressed to achieve the potential energy required for closing the contacts of circuit breaker.
In an air circuit breaker, there are two sets of contacts - power contact and control contacts. The power contacts comprise of a set of movable contacts and fixed contacts. In the Open (OFF) state of an air circuit breaker, the movable contacts and fixed contacts are separated and prevent the flow of current to the load/downstream devices connected to the circuit breaker. In the Closed (ON) state of an air circuit breaker, contact is established between the movable contacts and fixed contacts thus completing the electrical circuit for the load/downstream devices.
Circuit breakers are equipped with Charging Springs that are compressed (Charged) to store the potential energy which when released upon the actuation of the Closing (ON) command, is transferred into the movement of the movable contacts.
The compression (charging) of the charging springs can be achieved through the following
ways-
1) Electrical charging
2) Manual charging

During Electrical charging, the springs are compressed through a motor driven gearbox assembly (Electrical Charging Device i.e. ECD) coupled to the charging shaft of the circuit breaker mechanism. The ECD motor terminals are connected in series with the gearbox normally closed (NC) micro-switch terminals. When the springs are completely charged, the NC micro-switches change their state and disconnect the supply to motor until the springs are discharged during closing/ON condition.
In case of manual charging, the charging springs are compressed through multiple strokes of the charging handle. The charging handle is coupled with a pair of pawl and ratchet mechanism which rotates the charging shaft and subsequently charges the spring.
The two methods as mentioned above are mutually independent. Thus, even during manual charging, there can be a situation when the ECD motor can be remotely energized and the circuit breaker springs will get electrically charged. Such a condition may be hazardous towards the safety of the operator. Additionally, there is no provision for electrical indication for manual charging of the circuit breaker which can ensure the non-engagement of the Manual Charging handle further to which it will be safe to energize the ECD and charge the springs electrically.
During maintenance of the circuit breaker, it is necessary to disconnect the power circuit as well as the control circuit for ensuring safety of the user. While testing, the circuit breaker can be manually/locally operated and is also equipped with electrical and electronic devices that can be used for remotely operating the circuit breaker.
During electrical charging of the springs, the Electrical Charging Device can be energized without accounting for the status of manual charging by the user. Hence it is required to provide an electrical indication for the manual mode of charging based upon which the ECD
can be energized.
During maintenance of circuit breaker, the user ensures the disconnection of power supply and the control supply. Additionally, the circuit breaker springs are discharged for ensuring operational safety. Post maintenance, when the breaker is resumed into service, there could

be a situation that the control supply can accidentally turn live and start charging the springs electrically while the user actually is trying to manually charge the breaker. This poses risks to the user's safety and hence it is required to provide isolation of supply to ECD during manual charging of the circuit breaker.
Thus, it becomes very important to have an interlocking arrangement between the Manual charging handle and the Electrical Charging Device to prevent undesirable charging of the springs in manual and electrical mode simultaneously. Further, the arrangement should provide a clear electrical indication regarding engagement of the Manual Charging handle to indicate manual operation in progress ahead of remote operation of ECD. Such an arrangement needs to be very economical; also it should adhere with the space limitations of the breaker.
The present invention therefore provides an electrical interlocking arrangement to ensure electrical discontinuity in the circuit of the Electrical Charging Device during the Manual charging of the springs. Also, a pair of electrical contacts is provided which can serve as an indication of manual charging process, ahead of energizing the electrical charging device.
OBJECTS OF THE INVENTION
A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.
Another object of the present invention is to provide an integrated safety switch assembly for operational safety in circuit breakers.
Another object of the present invention is to provide an electrical indication of engagement of charging handle during manual charging operation.

Yet another object of the present invention is to provide complete isolation of ECD supply during manual charging process.
These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
There is provided an integrated safety switch assembly for operational safety in circuit
breakers.
According to one aspect of the present invention, there is provided an integrated safety switch assembly for operational safety in circuit breakers providing status indication for manual charging and electrical cut-off during manual charging, said device comprising a charging handle; an actuator means fixed on a slot of said charging handle using a screw; a plurality of charging spring means coupled to a charging shaft; an electrical charging device coupled to said charging shaft; a micro switch assembly mounted on a mechanism side plate using a plurality of screws, plain washers and spring washers; a pair of contacts for providing electrical indication of engagement of charging handle during manual charging operation; wherein said electrical charging device adapted to rotate said charging shaft thus compressing said charging spring means.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.
Fig 1 illustrates the isometric view of the Breaker.

Fig.2 illustrates the isometric view of the Breaker showing the Electrical Charging Device (ECD) coupled with the charging shaft.
Fig.3 illustrates the detailed isometric view of the safety switch assembly.
Fig.4 illustrates the isometric view of Charging handle assembly.
Fig.5 illustrates the electrical circuit diagram for the safety switch assembly.
DETAILED DESCRIPTION OF THE INVENTION
Accordingly in the present invention an integrated safety switch assembly for operational safety in circuit breakers is provided giving status indication for manual charging and electrical cut-off.
FEATURES:
- Electrical supply Cut-off for electrical charging device during manual charging through handle operation
- Status indication of Manual Charging during Charging Handle Operation
- Spring Charging Safety switch actuator assembly on Charging handle
- Safety Switch assembly on breaker mechanism side plate. Minimum number of components, easy to manufacture and assemble.
Constructional elements:
1. Charging Handle
2. Safety switch actuator
3. Micro-switch assembly
Construction and Operation:

As shown in Fig.l, the Breaker Mechanism consists of compression type charging springs (2) and a charging handle (1) coupled to the charging shaft (5). The Charging springs (2) get fully compressed after 7 strokes of the charging handle (1).
As shown in Fig 2, The Electrical Charging Device (6) is coupled to the Charging shaft (5). When the ECD is energized, it rotates the Charging Shaft (5) thus compressing the Charging Springs (1).
The functions performed by the innovation are follows:
I. Electrical supply Cut-off for electrical charging device during manual
Charging through handle operation
When the Charging handle (1) is in reset position, the safety switch actuator (4) assembled on the Charging Handle (1), presses the actuating link of Micro-switch assembly (3). This keeps the pair of normally open (NO) contacts of the Micro-switch in closed condition. As shown in Fig 5 a, the pair of contacts mentioned above can be connected in series with the electrical circuit of the Electrical Charging Device (ECD). Thus, in case of manual charging, due to engagement of the Charging handle, the Charging handle actuator will relieve the micro-switch. As a result, the switch will changeover from a closed state into an open state thus disconnecting the circuit of ECD. This ensures that the ECD is electrically disconnected in case of manual charging operation, thus, providing safety to the user.
II. Status indication of Manual Charging during Charging Handle Operation
When the Charging handle (1) is in reset position, the safety switch actuator (4) assembled on the Charging Handle (1), presses the actuating link of Micro-switch assembly (3). This keeps the pair of normally closed (NC) contacts of the Micro-switch in open condition. As shown in Fig 5b, the pair of contacts mentioned above can be utilized for providing electrical indication for engagement of Charging Handle during manual charging operation.

During manual charging, engagement of the Charging handle will relieve the micro-switch. As a result, the switch will changeover from an open state into a closed state thus providing electrical indication for manual charging in progress. This will act as a visual status indication of Manual Charging and prohibit a user from energizing the Electrical Charging
Device.
III.Retrofitting in field possible with minimum number of components:
The safety switch actuator (4) is fixed on one side of the Charging Handle (1) using a screw. The axial movement of the actuator is limited by its positive location within the side slot of the Charging handle. The micro-switch assembly can be mounted on the Mechanism side plate (6) using screws, plain washers and spring washers. The wires of the micro-switch assembly can be terminated on the control contacts.
Thus, the Safety switch assembly can be mounted with ease by the user without any modification on the existing components.
ADVANTAGES:
1) Complete isolation of ECD supply during manual charging process
2) Reliable indication of Manual Charging of the circuit breaker
3) Suitable for field retrofitting
4) Minimum number of components, easy to manufacture
5) Low cost of retrofitting
Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein with modifications. However, all such modifications are deemed to be within the scope of the claims.

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

WE CLAIM
1. An integrated safety switch assembly for operational safety in circuit breakers providing status indication for manual charging and electrical cut-off during manual charging, said assembly comprising:
a charging handle (1);
a safety switch actuator (4) means fixed on a slot of said charging handle (1) using a
screw;
a plurality of charging spring means (2) coupled to a charging shaft (5), said charging shaft having slot means;
an electrical charging device (6) coupled to said charging shaft (5);
a micro switch assembly (3) mounted on a mechanism side plate (6) using a plurality of screws, plain washers and spring washers;
a pair of contacts for providing electrical indication of engagement of charging handle during manual charging operation;
wherein said electrical charging device adapted to rotate said charging shaft thus compressing said charging spring means.
2. Assembly as claimed in claim 1 wherein said safety switch actuator(4) is located within the slot on charging shaft to arrest its axial movement.
3. Assembly as claimed in claim 1 wherein said micro switch assembly (3) further comprising an actuating link adapted to get actuated through said safety switch
actuator (4).

4. Assembly as claimed in claim 1 wherein said charging handle during manual charging relieving said micro-switch assembly thereby providing changeover from a close state to an open state thereby disconnecting circuit of electrical charging device.
5. Assembly as claimed in claim 1 wherein said charging handle during manual charging relieving said micro-switch assembly thereby providing changeover from an open state to a closed state thus providing electrical indication for manual charging in
progress.
6. An integrated safety switch assembly for operational safety in circuit breakers as
herein described and illustrated with reference of accompanying drawings.