FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
APPARATUS FOR REDUCTION IN DELATCHINC TIME OF
CIRCUIT BREAKER
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Abhang Pravin, Mandlik Kalpesh and Thore Ramchandra of Crompton Greaves Ltd, S3 Division; Switchgcar Complcx, A-3, M'IDC, Ambad, Nashik-422010 Maharashtra, India; ail Indian Nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

Field of the Invention:
This invention relates to the field of mechanics.
Particularly, this invention relates to circuit breakers.
Still particularly, this invention relates to de-latching mechanism of circuit breakers.
Background of the Invention:
Circuit breakers provide the breaking of circuit upon detection of faulty electrical conditions in the operation of associated assemblies. Thus, a circuit breaker acts as a safety device for said associated assemblies. As sensitivity of associated assemblies increase, it becomes imperative that circuit breakers be absolutely reliable in their working as a safeguard feature. Moreover, it is more essential that they act within specified time durations, in order to actuate its working upon detection of fault.
It has been a constant endeavour to improve this specified time durations by attempting to reduce the time between detection and actuation. Since actuation is a mechanical process involving mechanical parts, its change of state from rest to motion is a crucial time consuming factor. This time duration to overcome inertia is a measure of goodness of the circuit breaker.

Typically, when a fault occurs, it is sensed as sudden rise in current. The sensing unit sends an actuating signal to magnetically actuated coil assembly, which consists of stationary core, moving core fixed with plunger and an electrically actuated magnetic coil. When actuating signal is passed through coil, the core and the plunger gets magnetically picked-up and moves the moving core and the plunger attached to it. The plunger, which in turn, is in connection with the trigger effort end, pushes the trigger to actuate. The trigger holds a latch on its other side of its arm. When plunger moves trigger effort arm, in turn a mechanical force imbalance gets created at trigger-latch interface, which moves the latch. The latch holds the linkage mechanism of the circuit breaker, which keeps the circuit breaker in close condition. Due to imbalance as the latch moves, the linkage gets activated due to the energy stored in the Tripping spring attached to mechanism and the circuit breaker contacts gets open, within the specified time span.
This breaks the electric circuit to the associated assemblies. This is the de-latching phase of the circuit breaker assembly.
Prior Art:
It has been observed that the effort arm of the Latch is shorter and hence needs larger force, and more time, to actuate the plunger from its state of inertia.

It has also been observed that the moving mass of the coil is relatively higher, and hence the time required for actuation from its state of inertia is more.
There is need to arrest the above-cited time lags.
Objects of the Invention:
An object of the invention is to reduce the de-latching time of circuit breaker mechanism.
Another object of the invention is to improve operating speed of said circuit breaker mechanism.
Summary of the Invention:
According to this invention, there is provided a circuit breaker device comprising a trigger with an effort arm adapted to mechanically communicate with a plunger and coil through its axial direction, said plunger adapted and attached to moving core from said stationary core to break the circuit, characterised in that, said trigger having an increased length of effort arm adapted to exert force for actuating from said plunger in a reduced time frame, said plunger with a reduced diameter for decreasing its mass for faster actuation upon exertion of aid effort arm on said plunger, and said

moving core having reduced mass adapted to react to said movement of plunger with reduced time lag.
The said effort arm is an elongated effort arm with about .100% increase in length.
The said moving coi! mass is reduced by about 20% than that in prior art.
The said plunger mass is reduced by about 25% than that in prior art.
Brief Description of the Accompanying Drawings:
Figure .1 illustrates a prior art assembly of de-latching portion of the circuit breaker; and
Figure 3 illustrates a prior art assembly of the coil of the de-latching portion
of the circuit breaker.
The invention will now be described in relation to the accompanying drawings, in which:
Figure 2 illustrates a de-latching portion of the circuit breaker;

Figure 4 illustrates a coil of the dc-latching portion of the circuit breaker; and
Figure 5 illustrates a graph representing time travel required for actuation of a circuit breaker.
Detailed Description of the Accompanying Drawings:
Figure 1 illustrates a prior art assembly of de-latching portion of the circuit breaker; and Figure 3 illustrates a prior art assembly of the coil of the de-latching portion of the circuit breaker.
Reference numeral 1 refers to a trigger. Reference numeral 2 refers to a plunger. Reference numeral 3 refers to a coil. Reference numeral 4 refers to a holding latch. Reference numeral 5 refers to a moving core. Reference numeral 7 refers to a stationary core.
According to this invention, there is provided a magnetic coil device and trigger adapted to reduce de-latching time of circuit breaker device.
Figure 2 illustrates a dc-latching portion of the circuit breaker in accordance with this invention; Figure 4 illustrates a coil of the de-latching portion of the circuit breaker in accordance with this invention; and Figure 5 illustrates

a graph representing time travel required for actuation of a circuit breaker in accordance with this invention.
In accordance with an embodiment of this invention, there is provided a trigger with an effort arm (1A) of increased length. An increase in length causes de-latching force reduction by using longer effort arm of trigger.
In order to get required de-latching force with reduced moving mass of coil, the mechanical advantage of the trigger has to be increased as trigger acts as a first class type of lever. Mechanical advantage is achieved by increasing the effort arm of the trigger.
Typically, trigger effort arm length is increased by approximately 1.00 %.
In accordance with another embodiment of this invention, there is provided a moving core (5A) and plunger (2A) with a relatively reduced mass. Thus moving mass is reduced.
Moving mass of coil affects the initial pick up time of coil due to its inertia, which affects de-latching time. In short if moving mass of coil is more, the de-latching time of a circuit breaker will be more.
This embodiment reduces the initial pick up time ('A', depicted, in figure 5) of the moving mass of coil and plunger. The de-latching force cannot be taken below a certain value or the system will be ineffective and de-latching will not take place. Typically, reduction is mass is obtained by reduction is

shape and thickness of moving core. Typically, plunger diameter is reduced to reduce mass.
Typically, moving mass of coil is reduced by 20%,
Typically, plunger mass is reduced by 25%
In accordance with this invention, both the above things provide effective reduction in operating time for Dc-latching.
These modifications and design changes have been made to get the required minimum dc-latching force and ultimately the dc-latching time.
Typically, said embodiments result in 21 % reduction in dc-latching time.
Due to this invention, the circuit breaker achieves reduction in dc-latching time. Further, it improves its operating speed typically from about 28msec to about 22msec for 400KV range circuit breaker.

We claim,
1. A circuit breaker device comprising a trigger with an effort arm adapted to mechanically communicate with a plunger and coil through its axial direction, said plunger adapted and attached to moving core from said stationary core to break the circuit, characterised in that, said trigger having an increased length of effort arm adapted to exert force for actuating from said plunger in a reduced time frame, said plunger with a reduced diameter for decreasing its mass for faster actuation upon exertion of aid effort arm on said plunger, and said moving core having reduced mass adapted to react to said movement of plunger with reduced time lag.
2. A device as claimed in claim 1 wherein, said effort arm is an elongated effort arm with about 100% increase in length.
3. A device as claimed in claim 1 wherein, said moving coil mass is reduced by about 20%.
4. A device as claimed in claim f wherein, said plunger mass is reduced by about 25%.