CLIAMS:1. A contact resetting system in a circuit breaker to bring , the contact resetting system characterized in that comprising:
a reset spring means, confined in a pre-loaded condition;
said reset spring having at least one end coupled to an extension of a latch link and another end coupled to a slot provided on a circuit breaker cassette;
wherein in the event of fault,
at least one contact in said circuit breaker cassette is configured to repel and flip from their original position;
and said reset spring is configured to transmit a force to the latch link so as to overcome the opposing forces of the repelled contacts to attain their original position.

2. The contact resetting system as claimed in claim 1, wherein, said reset spring is positioned between said extension in said latch link and said slot in said circuit breaker cassette, and said slot is resizable to accommodate said reset spring based on the force required.

3. The contact resetting system as claimed in claim 1, wherein, said reset spring is triggered on receipt of a TRIP command from at least one means selected from a thermal magnetic release or a microprocessor release or an external accessories or a push to trip (test) button, or any combination thereof.

4. The contact resetting system as claimed in claim 4, wherein, said operating handle/knob is projected outwards on an outer cover of a circuit breaker.

5. The contact resetting system as claimed in claim 1 and claim 3, wherein, said reset spring is a compression spring and configured to compress and release during resetting and tripping, respectively.

6. The contact resetting system as claimed in claim 1, wherein, a trip unit in said circuit breaker cassette is configured to detect a fault in a monitored and/ or non-monitored circuit so as to enable said pair of contacts to repel and flip by means of an operating spring, thereby triggers said operating handle/knob to said “TRIP” operating position.

7. The contact resetting system as claimed in claim 1, wherein, said contacts comprise a movable contact and/or a fixed contact.

8. An improved circuit breaker for resetting of the repelled contacts, comprising a knob fitted with a fork, moving contact(s), fixed contact(s), a drive shaft, a trip plate, wherein, in response to a fault, the moving contact(s) in at least one pole are configured to repel from the fixed contact(s) and gets locked or flipped crossing an expansion/compression limit of spring(s) depending on the fault, said improved circuit breaker CHARACTERIZED IN THAT it includes:
a spring means placed between an extended portion of a latch link and a cavity present on a surface of a cassette, wherein:
said spring means is extendable to move said latch link to an open position (a TRIP position); and
the spring means is pre-loaded in the latched condition and is configured to provide a force when a latch bracket delatches said latch link to enable resetting of the repelled contacts.

9. The improved circuit breaker as claimed in claim 8, wherein said spring means, in response to a trip command, is configured to reset said repelled contacts automatically and thereby enabling a knob of said circuit breaker to attain a trip position so as to indicate an occurrence of a fault.

10. The improved circuit breaker as claimed in claim 8, wherein said spring means, in response to resetting command, is configured to be loaded and thereby latches the latch link to the latch bracket.
,TagSPECI:TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to circuit breakers, particularly to flip-lock contact system for resetting the contact system of the circuit breaker, and more particularly to a mechanism to reset the moving contacts of circuit breaker systems after a fault event.

BACKGROUND

[002] A circuit breaker is a mechanical switching device capable of making, carrying and breaking currents. Under normal circuit conditions it will make the circuit closed allowing current to flow for a specified time and under specified abnormal circuit conditions it enables breaking of the circuit thereby preventing further flow of supply. The electric circuit breakers have tripping means which cause tripping of the breaker for interruption of the circuit when the current flowing through the breaker is in excess of a predetermined threshold value.

[003] Circuit breakers such as molded case circuit breakers (MCCB) are employed for current interruption. More particularly MCCBs are utilized to protect downstream equipments from damage during adverse conditions prevailing during the operation of the circuit in which molded case circuit breaker is employed. During adverse conditions like short circuit, the current rises to an alarmingly high level. This high current may cause damage to the parts in the electrical system. Hence during these conditions the circuit has to be opened to protect the parts which are connected after the breaker. Circuit breaker operating mechanism actuates the breaker contacts to open in the event of fault in a circuit. A circuit breaker can be manually opened and closed, as well as automatically opened to protect conductors or equipments from damage caused by excessive heating due to over current in abnormal conditions such as overload or short-circuit.

[004] The mechanism of the circuit breaker plays a vital role in determining the credibility of the circuit breaker. A good mechanism ensures quick and manually independent opening and closing of contact system.

[005] Five operations performed by the MCCB mechanism are:
a. ON
b. OFF
c. RESET
d. TRIP
e. TRIP FREE
The first three operations are initiated by an operator handle/knob. Whereas the remaining are triggered by the trip signal given by the release which senses the abnormal conditions and gives TRIP command to the mechanism, so that the latter opens the circuit.

[006] When the circuit breaker contacts are closed to allow the flow of electrical current, the operating handle of an operating mechanism is in the "ON" position. To stop the current flow manually, the operating handle may be shifted to the "OFF" position thereby opening the electrical contacts. Upon attainment of a pre-determined condition (trip event), such as ground fault or overload, the operating mechanism of the circuit breaker will allow the operating handle to a tripped position between the "ON" position and the "OFF" position. Before the circuit breaker may be turned "ON", the operating mechanism in the circuit breaker must be reset.

[007] However, when a current limiting molded case circuit breaker with flip-lock contact system faces the fault, the contacts repel open and will get locked before the release and mechanism could react. Once the trip command is given by release to bring the contact system back to its normal condition, it may require force more than what is offered by conventional mechanism..

[008] The prior art document, US 5122771 A discloses a molded case circuit breaker combined accessory actuator-reset lever to activate an auxiliary device in a circuit breaker when the circuit breaker contacts are open and closed and to reset the trip mechanism when the circuit breaker contacts are opened. The prior-art US 5122771 discloses actuation of an auxiliary device to provide visual indication of ON-OFF condition of the contacts

[009] The prior art document, US 4789848 A discloses molded case circuit breaker latch and operating mechanism assembly having an electronic trip circuit contained within the circuit breaker enclosure that includes a reset spring in cooperation with the circuit breaker latch spring to ensure manual reset of circuit breaker after an automatic trip function. The reset spring allows the circuit breaker latch assembly to be manually reset upon minimum travel of the circuit breaker operating handle. The prior-art US 4789848 provides resetting of mechanism with additional spring.

[0010] The prior art document, EP 1111645 A2 a circuit breaker accessory reset system for a circuit breaker. The reset system further includes a compliant device for communicating a reset force from the handle to be accessory device, the reset force provided for resetting the accessory device. The prior-art EP 1111645 discloses transfer of reset force from handle to an accessory.

[0011] However, none of the above cited prior-art document or the existing prior-art discloses a mechanism to reset all the flipped contacts..

[0012] The hitherto reset system in circuit breakers enhances main spring force of the operating mechanism due to the increase in the operating forces of the handle/knob in the event of “ON”, “OFF” and “RESET” position. The stresses of the components connected proximate to the main springs will be also higher therefore strengthening of the components may be needed. Also, such reset mechanisms may not be functional in case of multi-pole circuit breakers as the reset system will try to reset the repelled Moving Contact(s) by bringing the mechanism to TRIP position and thereby may reset only one or two contacts. The trip velocity of circuit breaker may not increase by means by such reset system.

[0013] Thus, in view the drawbacks of the existing reset systems in circuit breakers, there exists a dire need to provide an improved contact reset system that overcome the drawbacks of the hitherto mechanisms and thereby allowing reset of the pair of contacts separated in the event of fault to return to their original position .

SUMMARY OF THE INVENTION

[0014] The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

[0015] A primary object of the present invention is to provide an improved, cost effective and an efficient contact reset system that overcome the drawbacks of the hitherto technique for enabling a circuit breaker to bring the breaker to TRIP instantaneously after an event of fault.

[0016] Another object of the present invention is to provide a contact reset system in a circuit breaker that provides assistance to a main springs of the operating mechanism for resetting all the repelled contacts provided in a circuit breaker

[0017] Accordingly, the present invention provides a contact reset mechanism comprising a reset spring coupled to a circuit breaker latch assembly. The reset spring eliminates the need of accelerated force from the main spring for resetting all the repelled contacts provided in a circuit breaker.

[0018] In one implementation, a resetting system is provided in a circuit breaker, the resetting system comprises the reset spring confined in a pre-loaded condition wherein the reset spring is having at least one end coupled to an extension of a latch link and another end coupled to a slot provided on a circuit breaker cassette. In the event of fault, at least one contact in said circuit breaker cassette is enabled to repel, and flip from its original position and the contact reset spring further transmits a force to the latch link of the latch assembly, enabling the contact coupled to the drive shafts to return to its original position and brings the mechanism (circuit breaker) to TRIP position

[0019] In one implementation, an improved circuit breaker for resetting of the repelled contacts, comprising a knob fitted with a fork, moving contact(s), fixed contact(s), a drive shaft, a trip plate, wherein, in response to a fault, the moving contact(s) in at least one pole are configured to repel from the fixed contact(s) and gets locked or flipped crossing an expansion/compression limit of spring(s) depending on the fault is disclosed. The improved circuit breaker includes a spring means placed between an extended portion of a latch link and a cavity present on a surface of a cassette, the spring means is pre-loaded in the latched condition and is configured to provide a force when a latch bracket delatches said latch link to enable resetting of the repelled contacts.

[0020] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0021] Figure 1 illustrates an isometric view of the mechanism with contact reset provision, in accordance with an embodiment of the present subject matter.

[0022] Figure 2 illustrates an exploded view of the mechanism with contact reset provision, in accordance with an embodiment of the present subject matter.

[0023] Figure 3 illustrates a repelled contact reset mechanism in ON position, in accordance with an embodiment of the present subject matter.

[0024] Figure 4 illustrates a repelled contact reset mechanism in ON position, in accordance with an embodiment of the present subject matter.

[0025] Figure 5 illustrates a repelled contact reset mechanism in TRIP position, in accordance with an embodiment of the present subject matter.

[0026] Figure 6 illustrates a repelled contact reset mechanism in TRIP position, in accordance with an embodiment of the present subject matter.

[0027] Figure 7 illustrates a latch link, in accordance with an embodiment of the present subject matter.

[0028] Figure 8 illustrates a circuit breaker cassette, in accordance with an embodiment of the present subject matter.

[0029] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0030] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0031] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0032] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0033] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0034] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0035] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0036] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0037] A person skilled in the art will appreciate that for understanding purpose the present invention is explained with the help of a molded case circuit breaker however the disclosed method shall not be considered as the limiting factor for the scope of present invention.

[0038] The various components that may be used throughout the invention are as given below:
1 MOUNTING PLATE
2 LATCH LINK
3 UPPER LINK
4 UPPER LINK RIVET
5 LOWER LINK
6 FORK
7 LATCH BRACKET
8 LATCH BRACKET PIN
9 FORK SPRING PIN
10 LATCH LINK PIN
11 FORK RIVET
12 SPACER
13 TRIP PLATE PIN
14 TRIP PLATE
15 TRIP BIASING SPRING
16 RESET PIN
17 SPRING PIN
18 MAIN SPRINGS
19 CONTACT RESET SPRING
20 DRIVE SHAFT PIN
21 KNOB
22 MOVING CONTACT
23 FIXED CONTACT
24 DRIVE SHAFT
25 Cassettes

[0039] In one implementation, figure 1 illustrates an isometric view of a reset mechanism, in accordance with an embodiment of the present subject matter.

[0040] Referring now to figure 2, an exploded view of resetting mechanism is provided. In one implementation and as shown in the figure 2,a fork (6), is mounted on a mounting plates (1) and the fork (6) is fitted with an operating handle/knob (21) that operates the fork (6) so as to enable the operating mechanism to a desired position. The upper links (3), lower links (5) and main springs (18) are placed in their respective positions in the spring pin (17) and together the assembly is riveted on either side of a latch link (2) by means of upper link rivet (4). Further, the latch link assembly is hinged to the mounting plates (1) by means of latch link pin (10). Similarly, the latch bracket (7) is hinged on the mounting plates (1) with the help of the latch bracket pin (8) and the trip plate (14) is hinged along with the trip biasing spring (15) to the mounting plates (1) with the help of the trip plate pin (13). The rollable reset pin (16) is assembled with the latch link (2) to reset the operating mechanism to an OFF position and to stop the fork (6) in the trip position. The main spring (18) provides a force required to operate the breaker and is mounted to the spring pin (17) and fork (6) with the help of the fork spring pin (9). The contact reset spring (19) is used to reset the repelled contacts of the breaker automatically. The fork rivet (11) is used to pivot the fork (6), prevents the fork (6) from collapsing and the fork (6) can swivel upon the fork rivet (11) within the limits its designed for. The spacer (12) is used to maintain the rigidity of the mechanism holding the parts of the mechanism listed in the table in their respective position preventing from collapsing and maintaining the mechanism as a modular assembly.

[0041] In one implementation, the mainsprings (18) are triggered by means of an operating handle/knob (21) as mounted on a fork (6) wherein the operating handle/knob (21) is projected outwards on an outer cover of a circuit breaker and is configured to indicate at least one of “ON” and/or “OFF” and/or “TRIP” operating position.

[0042] In one implementation, the vertical position of the operating handle/knob (21) is aligned towards line side considering the breaker is mounted vertically and the viewer is seeing the breaker from the load side, is marked as “ON” operating position. And the operating handle/knob (21) is operated towards the viewing direction to reach the OFF position. The operating handle/knob (21) is positioned between “ON” and “OFF” position by means of reset pin (16) to indicate a “TRIP” position.

[0043] In one implementation, the contacts comprise a fixed contact (23) and/or a movable contact(s) (22) that is flipped in the event of fault.

[0044] Referring now to figure 7 and figure 8, an extension as profile A in latch link (2) and a slot as surface B in circuit breaker cassette is provided. In one implementation, the reset spring (19) is positioned between the extension in latch link (2) and a slot in the circuit breaker cassette (25) wherein the slot is resizable to accommodate said reset spring based on the force required.

[0045] Referring now to figure 3 and figure 4, the operating handle/knob (21) in “ON” position is provided. In one implementation the fork (6) is positioned far away from a trip system wherein the upper links (3) and lower links (5) is holding the pair of contact (22 and 23) in the closed circuit condition with the help of the drive shaft pin (20) provided in a drive shaft (24).

[0046] Referring now to figure 5 and figure 6, the operating handle/knob (21) in “TRIP” position is provided. In one implementation, the fork (6) is positioned between the “ON” and “OFF” positions and the position is constrained by the rotation of latch link (2). The Reset pin (16) stops the latch link (2) from further rotation. The rotation of latch link (2) is allowed by the delatching of the latch bracket (7).

[0047] In one implementation, resetting of the breaker is done by moving the operating knob/handle (21) towards the “OFF” position from the “TRIP” position. The operating knob/handle (21) indicates an “OFF” position by means of fork (6) positioning very near to the trip system wherein the upper links (3) and lower links (5) is holding the contacts in the open circuit condition with the help of the drive Shaft Pin (20) provided on the drive shaft (24). A RESET position is witnessed when trying to reset the breaker from the “TRIP” position and when the operating knob/handle (21) is left free, and thus is resting in the “OFF” position. The movement of the operating handle/knob (21) loads the main springs (18) and latches the Latch Link (2) to the Latch Bracket (7) and allowing an operator personnel to switch “ON” the breaker. The mechanisms is called semi-automatic mechanisms since for ON and OFF operation, the knob of the breaker has to be taken from their respective ON or OFF positions to a position called dead center beyond which the mechanism becomes independent of the operator and completes the respective action automatically.

[0048] In exemplary embodiment, during an event wherein the current limiting MCCB faces fault higher than the intended current limit, the moving contact(s) (22) in each pole of a multi-pole circuit breaker repels from the Fixed Contact(s) (23) and gets locked or flipped crossing the dead center of the springs. The number of poles getting repelled depends on the fault level. During this condition the mechanism is in “ON” position thereby holding the drive shaft (24) in ON position. The Moving Contact(s) (22) repel open faster than the Thermal Magnetic Release which gives command for the mechanism to trip. When the mechanism receives the command, the fault is already been cleared by the repulsion & locking of moving contacts (22). By the time, when the TRIP command is received by mechanism, the Trip Plate (14) rotates and de-latches the Latch Link (2) enabling the rotation of Latch Bracket (7). The Contact Reset Spring (19) enables an additional force required to reset the whole breaker (may be 3 poles or 4 poles).

[0049] In one implementation, an improved circuit breaker for resetting of the repelled contacts, comprising a knob fitted with a fork, moving contact(s), fixed contact(s), a drive shaft, a trip plate, wherein, in response to a fault, the moving contact(s) in at least one pole are configured to repels from the fixed contact(s) and gets locked or flipped crossing an expansion/compression limit of spring(s) depending on the fault, said improved circuit breaker includes a spring means placed between an extended portion of a latch link and a cavity present on a surface of a cassette, wherein said spring means is pre-loaded in the latched condition and is configured to provide a force when a latch bracket delatches said latch link to enable resetting of the repelled and locked/flipped contacts.

[0050] In one implementation, said spring means, in response to a trip command, is configured to reset said repelled contacts automatically and thereby enabling a knob of said circuit breaker to attain a trip position so as to indicate an occurrence of a fault.

[0051] In one implementation, said spring means, while resetting, is configured to be loaded and latch link latches to the latch bracket subsequently.

[0052] Some of the important features of the present invention, considered to be noteworthy are mentioned below:
1. The design of the profiles of the parts can be modified easily as the requirement change.
2. Since a compression spring is used for the purpose, there is no much limitation in designing and manufacturing except the space availability.
3. The breaker will come to TRIP condition automatically after clearing the faults.
4. Maintains the normally required main spring force.
5. Operating forces (ON, OFF, RESET) will be optimal.
6. Stresses of the components connected to the springs will be optimal.
7. Trip velocity of the mechanism increases drastically.

[0053] It may be understood by the person skilled in that art that, the coupling, joining, fitting of the two components mentioned the present invention may be achieved by any of the existing coupling techniques that may include but not limited to nut and bolt arrangement, gluing, pasting, welding, and the like.

[0054] Although a contact resetting system and trip velocity/speed enhancer for an improved circuit breaker have been described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples of implementations of the contact resetting system and trip velocity/speed enhancer for an improved circuit breaker.