A) TECHNICAL FIELD

[0001] The present invention generally relates to circuit breakers and particularly relates to current limiting circuit breakers. The present invention more particularly relates to a tripping mechanism for moulded case circuit breakers and miniature circuit breakers.

B) BACK GROUND OF THE INVENTION

[0002] Circuit breakers are the mechanical switching devices capable of making, carrying and breaking currents under normal circuit conditions and also making, carrying for a specified time and breaking currents under specified abnormal circuit conditions. A circuit breaker basically consists of a pair of separable contacts and an interrupting medium. The function of the contacts is to conduct the electrical current, when the breaker is closed and withstand the arcs while interrupting. By making the moving contact to touch the stationary contact, an electric current flows and the breaker is closed. An electric arc develops by driving the moving contact away from the stationary contact. By quenching the electric arc, the current flow stops and the breaker is opened.

[0003] In the existing technique, when there is a fault condition in the circuit breakers, the contacts repel and the release unit will provide the signal to the trip system for the mechanism to trip by electrical means. A subsequent amount of time is taken to open the contacts of the breaker during fault condition. Furthermore in the existing technique, the trip time is high since the signal to trip comes from the release unit of the breaker and thus there is some time delay. This time delay causes more damage to the contact system of the circuit breakers and reduces the life of the circuit breaker.

[0004] Hence there is a need for a tripping mechanism for circuit breakers which enables faster tripping. There is also a need to provide a mechanism for improving the life of the circuit breaker.

[0005] 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 PRESENT INVENTION

[0006] The primary object of the present invention is to provide a faster tripping system for circuit breakers.

[0007] Another object of the present invention is to develop a faster tripping system for circuit breakers to reduce the total trip time during the fault condition.

[0008] Yet another object of the present invention is to develop a faster tripping system to provide an effective way of achieving discrimination between the upstream breakers and downstream breakers.

[0009] Yet another object of the present invention is to develop a faster tripping system for circuit breakers to reduce the overall fault clearing time.

[0010] Yet another object of the present invention is to develop a faster tripping system for sensing the fault condition in the circuit breakers during contact repulsion.

[0011] Yet another object of the present invention is to develop a faster tripping system in which the sensing link and the tripping link receive the trip signal directly from the repelling contacts.

D) SUMMARY OF THE INVENTION

[0012] The various embodiments of the present invention provide a tripping mechanism for circuit breakers. The tripping mechanism includes a moving contact, a fixed contact connected to the moving contact, a sensing link mounted on the moving contact and a tripping link. Further a fault condition in the circuit breaker is sensed based on the position of the contacts and a trip signal is directly fed into the sensing link and the tripping link from the repelling contacts that result in tripping of the circuit breakers. Further the tripping of the circuit breakers reduces the overall fault clearing time.

[0013] According to one embodiment of the present invention, the tripping of the circuit breakers reduces the overall fault clearing time. The fault condition in the circuit breakers is sensed when the contact repels.

[0014] According to another embodiment of the present invention, the sensing link and the tripping link receives the trip signal directly from the repelling contacts. The sensing link transfers the torque from the moving contact to the tripping link. The torque transferred from the sensing link in turn provides the trip signal to the circuit breaker.

[0015] According to another embodiment of the present invention, the circuit breakers include a trip plate for receiving the trip signal. The sensing link is rotated along with the moving contact which in turn hits the tripping link. The effective discrimination between the upstream breakers and the downstream breakers is achieved by adjusting the angle at which the signal from the repelling contact is sensed.

[0016] According to another embodiment of the present invention, the fault in the circuit breakers is sensed faster than the release and the trip signal is given with a minimal time delay.

[0017] 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.

E) BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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:

[0019] FIG. 1 illustrates the perspective view of a circuit breaker assembly in the ON condition, according to one embodiment of the present invention.

[0020] FIG. 2 illustrates the perspective side view of a circuit breaker assembly in the ON condition, according to one embodiment of the present invention.

[0021] FIG.3 illustrates the perspective side view of a moving contact of the circuit breaker that repels open due to a short circuit condition, according to one embodiment of the present invention.

[0022] FIG.4 illustrates the perspective side view of the circuit breaker with a sensing link transferring the torque from the moving contact to the tripping link, according to one embodiment of the present invention.

[0023] Although the 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

[0024] In the following detailed description, a 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.

[0025] The various embodiments of the present invention provide a tripping mechanism for circuit breakers. The tripping mechanism includes a moving contact, a fixed contact connected to the moving contact, a sensing link mounted on the moving contact and a tripping link. Further a fault condition in the circuit breaker is sensed based on the position of the contacts and a trip signal is directly fed into the sensing link and the tripping link from the repelling contacts that result in tripping of the circuit breakers. Further the tripping of the circuit breakers reduces the overall fault clearing time.

[0026] According to one embodiment of the present invention, the tripping of the circuit breakers reduces the overall fault clearing time.

[0027] FIG. 1 illustrates the perspective view of a circuit breaker assembly in the ON position, according to one embodiment of the present invention. The circuit breaker assembly includes a moving contact 102, a fixed contact 104, a tripping link 106, a sensing link 108, and a trip plate 110.

[0028] The moving contact 102 and the fixed contact 104 of the circuit breaker are in the ON position. The sensing link 108 and the tripping link 106 receives the trip signal directly from the repelling contacts. The tripping link 106 and the sensing link 108 is arranged in such a way that it senses the fault when the contact repels and gives the trip signal. This reduces the time for giving the trip signal, thereby reducing the tripping time.

[0029] FIG. 2 illustrates the perspective side view of a circuit breaker assembly in the ON condition, according to one embodiment of the present invention. FIG.3 illustrates the perspective side view of a moving contact of the circuit breaker that repels open due to short circuit condition, according to one embodiment of the present invention. With respect to FIG.2, the moving contact 102 and the fixed contact 104 of the circuit breaker are in the ON position. The sensing link 108 receives the trip signal from the repelling contacts and further gives the trip signal through the tripping link 106 to trip the mechanism in the circuit breakers.

[0030] With respect to FIG. 3, the tripping time is considerably reduced as the trip signal received from the repelling contacts is directly fed into the mechanism of circuit breakers for faster tripping. The fault condition is sensed in the circuit breakers through the position of the contacts and causes tripping of the breaker, thereby reducing the overall fault clearing time.

[0031] FIG.4 illustrates the side perspective view of the circuit breaker with the sensing link transferring the torque from the moving contact to the tripping link 106, according to one embodiment of the present invention. Further as the moving contact 102 repels open, the moving contact comes in contact with the sensing link 108.

[0032] The sensing link 108 is rotated along with the moving contact 102 and the rotation causes the moving contact 102 to hit the tripping link 106. The tripping link 106 further hits the trip lever of the operating mechanism and causes the breaker to trip. During the fault condition in the circuit breakers, an arc is formed between the fixed contact 104 and the moving contacts 102. The arc has a tendency to erode the contact buttons. The arc has to be quenched faster to avoid the contact erosion due to which the breaker is tripped faster and the arc is quenched fast. This decreases the erosion of the contacts thereby increasing the life of the contacts.

G) ADVANTAGES OF THE INVENTION

[0033] The various embodiments of the present invention provide a tripping mechanism for circuit breakers. The tripping mechanism includes a moving contact, a fixed contact connected to the moving contact, a sensing link mounted on the moving contact and a tripping link. Further a fault condition in the circuit breaker is sensed based on the position of the contacts and a trip signal is directly fed into the sensing link and the tripping link from the repelling contacts that result in tripping of the circuit breakers. The tripping of the circuit breakers reduces the overall fault clearing time.

[0034] The advantages of the present invention includes sensing the fault condition when the contact repels and provides the trip signal, thereby reducing the time for giving the trip signal and the tripping time. Further the life of the circuit breaker also increases since the fault is cleared quickly.

[0035] The various advantages of the present invention include reducing the let through energy during a fault condition, since the breaker clears the fault quickly. Further the arrangement of components in the circuit breakers overcomes the problem of restricting of contacts during a fault condition.

[0036] The various advantages of the present invention include an effective discrimination between the upstream and downstream breakers are achieved by adjusting the angle at which the signal from the repelling contact is sensed.

[0037] 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.

[0038] 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 langue might be said to fall there between.

CLAIMS

What is claimed is:

1. A tripping mechanism for circuit breakers, the tripping mechanism comprising:

a moving contact;

a fixed contact connected to the moving contact;

a sensing link mounted on the moving contact; and a tripping link;

wherein a fault condition in the circuit breaker is sensed based on the position of
at least one of the moving contact and a fixed contact and a trip signal is directly
fed into the sensing link and the tripping link from the repelling contacts that result in tripping of the circuit breakers.

2. The tripping mechanism of claim 1, wherein the tripping of the circuit breakers reduces the overall fault clearing time.

3. The tripping mechanism of claim 1, wherein the fault condition in the circuit breakers is sensed when the contact repels.

4. The tripping mechanism of claim 1, wherein the sensing link and the tripping link receives the trip signal directly from the repelling contacts.

5. The tripping mechanism of claim I, wherein the sensing link transfers the torque from the moving contact to the tripping link.

6. The tripping mechanism of claim 5, wherein the torque transferred from the sensing link provides the trip signal to the circuit breaker.

7. The tripping mechanism for circuit breakers further comprises a trip plate for receiving the trip signal.

8. The tripping mechanism of claim 7, wherein the sensing link is rotated along with
the moving contact such that the sensing link comes in contact with the tripping
link.

9. The tripping mechanism of claim 1, wherein an angle at which a signal from the
repelling contact is adjusted to provide a discrimination between the upstream
breakers and the downstream breakers.

10. The tripping mechanism of claim I, wherein the tripping lever hits the trip lever
to provide for tripping the circuit breaker.

11. The tripping mechanism of claim 1, wherein the fault in the circuit breakers is
sensed faster than the release and the trip signal is given with a minimal time
delay.