Claims:1. A latch system for a circuit breaker, the system comprising:
a fork (16);
a resetting pin (17) comprises a substantially conical sloping surface (172), a stopper (173);
a latch link (6);
a plurality of latch link holes (62);
a main spring (18);
a latch bracket (14);
wherein the fork operatively guiding the resetting pin (17) such that the resetting pin is adapted to be inserted into the latch link hole (62) when the circuit breaker being in unloaded condition of the main spring (18);
wherein the fork operatively guiding the latch link (6) to latch position through the resetting surface (172) of the resetting pin (17) when the circuit breaker being resettled from TRIP condition;
wherein the resetting pin (17) operatively moves on a resetting profile (163) of the fork (16) thereby reducing resetting force and/or increasing a wear resistance at a contact position of the fork and the resetting pin;
wherein the fork operatively guiding the resetting pin (17) such that the latch link (6) and /or the latch bracket (14) is being moved to the latch condition thereby the resetting pin (17), the latch link (6) and/or the latch bracket (14) are being operatively engaged with a trip plate overlap (152);
wherein the conical sloping surface (172) of the resetting pin (17) adapted for self-locking of the resetting pin (17) with a latch bracket tripping cam (146) during the circuit breaker being ON and/or OFF and/or TRIP condition.
2. The system as claimed in claim 1, wherein the resetting pin (17) movement into the latch link hole (62) is being restricted by the substantial conical sloping surface (172) and the stopper of the resetting pin (173).

3. The system as claimed in claim 1, wherein the resetting pin (17) being adapted to move in a direction opposite to the substantially conical sloping surface (172) so as to contact the latch bracket tripping cam (146) such that the resetting pin (17) movement being restricted and being pushed the resetting pin (17) to an original condition.

4. The system as claimed in claim 1, wherein the stopper (173) is a one sided stopper.

5. The system as claimed in claim 1, wherein the resetting pin (17) being self-locked between the latch bracket (14) and the latch link (6).

6. The system as claimed in claim 1, wherein the system further comprises a knob (24).

7. The system as claimed in claim 1 or 6, wherein the knob (24) is operatively mounted on the fork (16).

8. The system as claimed in claim 1 or 6, wherein the knob (24) is being slide approximately upto a knob stopper (164) such that the knob stopper is adapted for avoiding slipping of the knob.

9. The system as claimed in claim 1 or 6, wherein the knob (24) is adapted for indicating the circuit breaker condition.

10. The system as claimed in claim 1 or 6, wherein the knob (24) is adapted to be positioned substantially at a center position when the circuit breaker is in TRIP condition.

11. The system as claimed in claim 1 or 6, wherein the system further comprises a plurality of mechanism linkages, wherein the plurality of mechanism linkages being adapted for discharging energy of a spring (16) for rotating a moving contact to trip condition and for positioning the knob substantially at a center position.

12. The system as claimed in claim 1 or 6, wherein the system further comprises a fork biasing spring (19), wherein the fork biasing spring (19) is adapted for providing energy such that the knob (24) is adapted to be positioned substantially at a center position.
, Description:TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to an operating mechanism of a circuit breaker, and more particularly a resetting pin locking arrangement for circuit breaker mechanism.

BACKGROUND

[002] Circuit Breaker is a mechanical switching device capable of making, carrying and breaking currents. Under normal circuit conditions it will make the circuit closed, carry current for a specified time and breaks the circuit under specified abnormal circuit conditions.

[003] Circuit Breakers is employed for current interruption. More particularly Circuit Breakers are utilized to protect instruments from damage during adverse conditions prevailing during the operation of the circuit in which circuit breaker is employed. During adverse conditions like short circuit, over current or 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 after the breaker.

[004] A circuit breaker can be manually opened and closed, as well as automatically opened to protect conductors or equipment’s from damage caused by excessive heating due to over current in abnormal conditions such as overload or short-circuit.

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

[006] Five operations are to be performed by the Circuit Breakers mechanism. They are ON, OFF, TRIP, TRIP FREE and RESET.
[007] The first two operations are initiated by operator whereas the trip signal is given by the release which senses the abnormal conditions and gives TRIP command to the mechanism, so that the latter opens the circuit.

[008] The operator has access to the mechanism through the knob which will be projected outwards from the housing of the breaker. The knob is placed over the fork of the operating mechanism. Conventional type Circuit Breakers will feature three positions in the top cover near the knob to show ON, OFF and TRIP.

[009] When the knob indicates ON it means the breaker is in ON condition i.e., the current path is closed. Similarly, the position of the knob indicates the state of the circuit breaker.

[0010] According to standards, the top position of the knob (if the breaker is placed vertically) or the longest distant position of the knob away from the operator (if the breaker is mounted horizontally) should be marked as ON POSITION. The other extreme end in both cases is marked as the OFF POSITION. The knob will be near the center (based on the design of the mechanism) to indicate the TRIP POSITION.

[0011] As stated above, TRIP command is given automatically to the contacts by the release if it senses an abnormal condition like overload and short circuit. If the trip signal is given, the breaker opens the circuit and the knob goes to the trip position to show the operator that a fault has occurred in the system.

[0012] If the operator wants to switch ON the breaker after the breaker is tripped, he/she cannot do it without resetting the breaker. This is to make sure that the operator shouldn't switch ON the breaker before clearing the fault.

[0013] Resetting of the breaker is done by moving the knob (Driver link) towards the OFF position from the TRIP position. The knob is held in fork which is having resetting profile. During the resetting operation when knob is pushed towards OFF position the resetting pin assembled in latching link performs rolling action with fork profile which latches the link with latch bracket. Also while tripping it acts as stopper for fork to indicated exact TRIP condition at breaker level. This movement loads the mechanism spring and now it is possible for the operator to ON the breaker. All these mechanisms are 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 he mechanism becomes independent of the operator and completes the respective action by its own automatically.

[0014] US6727788 discloses an apparatus for operating a circuit breaker. The circuit breaker includes a housing, a cradle mounted in the housing and coupled to a handle and to a movable contact. The apparatus comprises a latch frame mounted in the circuit breaker housing. A latch roller as shown in figure A is mounted on the cradle of the operating mechanism of the circuit breaker. The latch roller is a single piece that spans the width of the cradle and seats underneath a surface of the latch member. The latch roller can be composed of metal, a composite material or a combination of metal and composite material. The latch roller can also be formed as an integral portion of the cradle. Note that the figures illustrate only one side of the cradle, an operating mechanism of the circuit breaker. A latch member is configured to selectively engage the latch roller and is rotatably coupled to the latch frame with a latch pivot pin. A reset pin is mounted on the cradle. A latch member is configured to selectively engage the reset pin and the latch member is rotatably coupled to the latch frame. A latch shaft assembly is rotatably mounted in the latch frame and selectively engaged by the latch member. Upon rotation of the latch shaft assembly, the latch shaft assembly will disengage from the latch member and cause the movable contact to move.

[0015] US6218919 discloses a decreased mechanical trip time latching system for use in a molded case circuit breaker assembly. The latching system comprising a quick release primary latch having a first primary latching surface and a second primary latching surface. Where the second primary latching surface b as shown in Fig B engages a first secondary latching surface located on an interactive secondary latch, to prevent the rotation of the quick release primary latch. The first primary latching surface engages a cradle latching surface, located on a cradle, to prevent the rotation of the cradle. Assembled to the interactive secondary latch is a trip bar. Activation of the trip bar rotates the secondary latch so that the first secondary latching surface moves out of contact with the second primary latching surface just prior to the interactive secondary latch making physical contact with the quick release primary latch. The quick release primary latch then rotates moving the first primary latching surface out of contact with the cradle latching surface thereby releasing the cradle. The cradle rotates and the operating system is activated to terminate current flow.

[0016] US7268654 discloses a latching mechanism for a movable member mounted for movement between first and second positions. The latching mechanism includes a primary latching mechanism mounted for movement between a latched position where the primary latching mechanism engages the movable member through surface contact 111 as shown in Fig C-2 to allow the movable member to move between the first and second positions, and an unlatched position where the movable member is disengaged for movement to the second position. A secondary latching element engages the first latching mechanism to hold the primary latching mechanism in the latched position, the secondary latching element being movable to move the primary latching mechanism to the unlatched position while remaining in engagement with the primary latching mechanism.

[0017] US 6590482 discloses a latching mechanism which includes a pair of cradles. Mechanism linkages are connected to each cradle and these pair of cradle is connected to each other. Primary latch is engaged with the cradle. Edge surface is positioned generally at the portion of cradle in the range of contact with roller pin 114 as shown in Fig D.A secondary latch element is engaging he primary latch which being movable to move the primary latching mechanism.

[0018] In the existing technology, although the prior art discloses latch mechanism, use of reset pin was not known from the prior art. The constructional features of these prior art provides substantial surface contact between latch bracket and latch Link which gives rise to sliding friction. Due to sliding friction after repeated use, there is a possibility of the latch means to wear out. Also the resetting pin requires tedious assembly process which not only increases product cost but also results in higher manufacturing cycle time. Further disadvantage of the prior art is the sliding force of friction between the latch bracket and the latch link resulting in the increase of the trip force.

[0019] Thus there is a need to provide for an enhanced latch mechanism for use in molded case circuit breakers which trip the circuit breakers with decreased trip force. To meet this requirement, there is provided a latch system having a resetting pin locking arrangement for circuit breaker mechanism.

SUMMARY
[0020] This summary is provided to introduce concepts related to, a latch system having a resetting pin locking arrangement for circuit breaker mechanism, and the same are further described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.

[0021] According to one aspect of the invention, there is provided a latch system for a circuit breaker, the system comprising: a fork; a resetting pin comprises a substantially conical sloping surface, a stopper; a latch link; a plurality of latch link holes; a main spring; a latch bracket; wherein the fork operatively guiding the resetting pin such that the resetting pin is adapted to be inserted into the latch link hole when the circuit breaker being in unloaded condition of the main spring; wherein the fork operatively guiding the latch link to latch position through the resetting surface of the resetting pin when the circuit breaker being resettled from TRIP condition; wherein the resetting pin operatively moves on a resetting profile of the fork thereby reducing resetting force and/or increasing a wear resistance at a contact position of the fork and the resetting pin; wherein the fork operatively guiding the resetting pin such that the latch link and /or the latch bracket is being moved to the latch condition thereby the resetting pin, the latch link and/or the latch bracket are being operatively engaged with a trip plate overlap; wherein the conical sloping surface of the resetting pin adapted for self-locking of the resetting pin with a latch bracket tripping cam during the circuit breaker being ON and/or OFF and/or TRIP condition.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0022] The detailed description is described with reference to the accompanying figures. In the figures, the digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

[0023] Figure 1 illustrates a perspective view of mechanism with cassette.

[0024] Figure 2 illustrates a mechanism assembly with structural members.

[0025] Figure 3 illustrates a mechanism assembly

[0026] Figure 4 illustrates a mechanism assembly in the ON condition

[0027] Figure 5 illustrates a mechanism assembly in the OFF condition

[0028] Figure 6 illustrates Cross section of the mechanism showing TRIP condition

[0029] Figures 7a & 7b illustrate a Resetting pin assembly

[0030] Figure 8 illustrates a self-locking of resetting pin

[0031] Figure 9 illustrates a Resetting Pin

[0032] Figure 10 illustrates a Latch bracket

[0033] Figures 11a & 11b illustrates a Trip Plate

[0034] Figure 12 illustrates a Fork

[0035] It is to be understood that the attached drawings are for purposes of illustrating the concepts of the invention and may not be to scale.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0036] The following clearly describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely a part rather than all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate the principles of the invention. The invention is described in connection with such embodiments, but the invention is not limited to any embodiment. The scope of the invention is limited only by the claims and the invention encompasses numerous alternatives, modifications and equivalents. Numerous specific details are set forth in the following description in order to provide a thorough understanding of the invention. These details are provided for the purpose of example and the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured.

[0038] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components, modules, units and/or circuits have not been described in detail so as not to obscure the invention.

[0039] Although embodiments of the invention are not limited in this regard, the terms “plurality” and “a plurality” as used herein may include, for example, “multiple” or “two or more”. The terms “plurality” or “a plurality” may be used throughout the specification to describe two or more components, devices, elements, units, parameters, or the like. Unless explicitly stated, the method embodiments described herein are not constrained to a particular order or sequence. Additionally, some of the described method embodiments or elements thereof can occur or be performed simultaneously, at the same point in time, or concurrently.

[0040] The present invention discloses a latch system having a resetting pin locking arrangement for circuit breaker mechanism. The present invention provides a latch mechanism for circuit breakers in which rolling co-efficient of friction plays role in deciding the Reset force required for resetting the circuit breaker & to ease the manufacturing. The present invention defines a way to structure a resetting pin with conically sloping surface with one sided stopper for insertion. Unlike the prior structure with the new resetting pin, there is no need to make separate sub-assembly of with latch link. It is assembled only by inserting in latch link holes form any side at latch link resetting end such that its free rotation is maintained with respect to corresponding resetting / navigating profile of fork. In the final mechanism assembly, the resetting pin axial movement in latch link holes is restricted by conical profile & stopper surface of resetting pin. As the pin will try to move in the direction opposite the sloping surface will come in contact with latch bracket tripping cam which will restrict and push the pin back to original condition, while from other side the pin stopper will restrict the movement. Thus the conical slopping surface facilitates self-locking of resetting pin between latch bracket and latch link.

[0041] The present invention comprises of latch system as shown in figure 8 where in while resetting operation knob 24 is manually guided towards OFF condition shown in figure 5. The Knob 24 is mounted in fork by sliding it upto knob stopper feature 164. This Feature avoids the slipping of knob on one side of mechanism while on other side due to ingress protection cover and front cover knob slipping is protected. Knob should be able to indicate desired breaker condition, thus in TRIP condition the position of knob should be in center position. Mechanism linkages are structured in such a way that the main spring 16 as shown in figure 4, have to discharge its energy to rotate moving contact to trip condition as well as to position the knob in center position, thus an additional energy is provided by Fork Biasing spring 19 as shown in the figure 2 to bring knob at center position.

[0042] As the fork moves it guides the resetting pin 17 which is assembled in latch link holes 62 shown in figures 7-a & 7-b. When the breaker is in unloaded condition of main spring 18, the resetting pin 17 assembly is done by inserting it in latch link holes 62 from either side where it adjusts on latch link 6 as shown in figure 7a, figure 7b & figure 8 with the stopper 173. As the breaker is resetted from TRIP condition shown in figure 6 the fork guides the latch link 6 in its latch position through resetting surface 172 of pin 17. The resetting pin rolls over the resetting profile 163 of fork 16. This rolling motion not only reduced the resetting force but also increases wear resistance at fork & pin contact. As the fork 16 guided the pin 17 further the latch link is pushed along with latch bracket 14 on the resetting surface 141 to its latch condition where they are engaged with trip plate overlap 152.The resetting pin 17 consists of conical sloping surface 172 which facilitates self-locking of resetting pin 17 with latch bracket tripping cam 146 during ON, OFF &TRIP condition shown in figures 4, 5 & 6.

[0043] The invention has been described in a preferred form only and many variations may be made in the invention which will still be comprised within its spirit. The invention is not limited to the details cited above. A resetting pin locking arrangement for circuit breaker mechanism a system for isolated conversion of voltage to logical level as described above does not limit the scope of the present invention. The structure thus conceived is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. In practice the materials and dimensions may be any according to the requirements, which will still be comprised within its true spirit.

[0044] Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

[0045] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.