DESC:TECHNICAL FIELD

The present invention relates generally to a molded case circuit breaker (MCCB) and, particularly, to an improved structure that provides the modularity in components and connections of the MCCB.

BACKGROUND

A circuit breaker is a mechanical device capable of making, breaking and carrying normal currents and making and breaking currents under specified abnormal circuit conditions such as that of a short circuit or overload.

Circuit breakers are employed in the electrical system or network for switching and protection of electrical equipments. During adverse conditions like short circuit, the current shoots up to an alarmingly high value; this can pose grave threat to the electrical system, as it can cause damage to the equipments and loads installed downstream in the system. The circuit breaker clears the fault rapidly so as to minimize the damage caused by thermal and mechanical stresses to downstream equipments.

A moulded case circuit breaker is a circuit breaker, wherein the arc quenching and fault clearing process takes place inside housing. Broadly, it consists of contacts system, mechanism, currents sensing unit.

The contact system of the circuit breaker consists of fixed contacts and moving contact. During ON condition, a set of springs provide the contact force to maintain the moving contact in ON condition. The current conducts from the first fixed contact onto the moving contact and then onto the second fixed contact. The fixed contacts are designed in such a way that the during short circuit conditions, an electromagnetic force develops between the moving contact and fixed contacts. The force results in a clockwise torque on the moving contact. Meanwhile there is an anti clockwise torque provided by the springs acting on the contact. The electromagnetic torque acts against the spring torque and enables moving contact to open up and thus clear the fault.

The moving contact with the spring arrangement is neatly assembled inside a rotating chamber called shaft. Different arrangements of springs and shaft configurations are currently employed for maintaining contact pressure.

Arc chute assemblies, made up of deion plates neatly stacked up together are used for pulling, lengthening and quenching of electric arc during fault interruption.

A perforated metal sheet or mesh is used sometimes, so as to de-ionize and cool the hot ionized gases. In some breakers, perforated plastic sheet is used as an alternative.

Operating mechanism of the circuit breaker enables manually independent opening and closing of the contact system and does four operations: ON, OFF, Trip and Reset.

The trip unit senses the current flowing through the system, and under pre-specified abnormal conditions gives the command signal for the operating mechanism of the breaker to trip i.e., break the circuit. The trip unit used are generally either thermo-magnetic or electronic (microprocessor based) trip unit.

The various termination units/modules cater to the various types of termination like direct link, box clamp, rear, tunnel as per the customer requirements at the endpoint use.

Conventionally, a moulded case circuit breakers (referred here after as MCCB or breaker) can be divided into four main structural sub-assemblies,
1. Contact System assembly
2. Operating Mechanism Assembly
3. Release Assembly
4. Other Parts forming Outer body

Contact system assembly consists of different poles for each phase coupled together. The prior-art figure 1 (A) and figure 1 (B), figure 2, figure 3 and figure discloses the pole having two fixed contacts (10, 11) one moving contact and two half shells forming outer body of the pole. The Fixed contact and moving contact can be mutually coupled and decoupled. Further, the components marked B shows the coupling of operating mechanism with the poles A. The component B is trapped in between the two poles and used for transferring mechanism displacement to the poles.

1) There are various MCCB’s available in the prior-art, however there are certain limitations in the available MCCB’s. However the existing MCCB’s in the art has certain limitations, few of them are mentioned below: Use of Extension springs for contact pressure in exiting MCCBs constraint the toggling of Moving contact, and increase the dependency on Operating Mechanism.
2) In existing MCCB’s there is absence of Shaft pins for coupling of Mechanism to each contact systems enhance the chance of losses in Over travel or Contact pressure.
3) In existing MCCB’s there is absence of Visual inspection of Over travel or Contact Pressure at Pole level or Breaker level, increase the depth 7 time of analysis.
4) In existing MCCB’s there is there is a chance of vibrations between poles if they are coupled with a normal through pins. Vibrations during mechanical operations may cause nuisance tripping of system.
5) In existing MCCB’s the dependency of Release Box (Electronic tripping unit, ETU) to Basic Breaker is only on electrical screws, which may cause rise in overall Watt loss of the Breaker.

Thus, in view of the above mentioned limitations, there exists a need to provide an improved and efficient MCCB.

SUMMARY

This summary is provided to an improved molded case circuit breaker. This summary is not intended to identify essential features of the subject matter nor is it intended for use in determining or limiting the scope of the subject matter.

In one implementation, an over-travel indication, a unique feature of the present invention is disclosed. The over travel arrow marking on the shaft assembly quantifies the over travel given by mechanism module to the contacts in degrees as per marking scheme given on cassettes. This ensures the required contact pressure. Also, the exact over travel loss of shaft through the mechanism, if any, is clearly detected.

In one implementation, the present invention provides an improved MCCB wherein a cassette is provided with special features for pivoting the shaft to minimize the friction.

In one implementation, the present invention provides an improved MCCB wherein an operating mechanism is directly coupled with minimum three Poles avoiding transmission of rotation loss from one pole to another.

In one implementation, the present invention provides an improved MCCB wherein use of two pole connection screws out of four for operating mechanism fixing with the poles.

In one implementation, the present invention provides an improved MCCB wherein a TAC actuator is pivoted on a pole joining screw, an AUX actuator and an EOM indicator forms through pin caps from both extreme ends providing additional insulation.

In one implementation, the present invention provides an improved MCCB wherein a cover of the knob is provided which is fixed with knob by means of snap fits so that there placement is secured and any misplacing is avoided.

Accordingly, in one implementation, a molded case circuit breaker (MCCB) with a contact system (1) assembly, an operating mechanism (2) assembly, a release (3) assembly, and other parts (4) forming outer body is disclosed. The molded case circuit breaker (MCCB) comprises of at least one pole (11) assembly in the contact system (1) assembly. The operating (2) mechanism assembly comprises of a user interface, at least two shaft pins (22), at least two lower links (21), at least two mounting screws and nuts (12), at least two release side spacers (126), a TAC actuator (127), an aux actuator and an EOM actuator, a knob (23), and a chassis (42) with at least two features (423, 424). The operating mechanism (2) assembly is then assembled with the said at least one pole (11) and the knob (23) is assembled with a cover (24) for an ingress protection.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The detailed description is described with reference to the accompanying figures. In the figures, the left-most 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.

Figure 1 (A) and Figure 1 (B) illustrates a complete breaker assembly and pole internal components - exploded view, respectively available in the prior art, are shown, in accordance with an embodiment of the present subject matter.

Figure 2 illustrates a c-coupling of contact system and operating in prior-artis shown, in accordance with an embodiment of the present subject matter.

Figure 3 illustrates a c-coupling of contact system and operating mechanism in prior-art is shown, in accordance with an embodiment of the present subject matter.

Figure 4 illustrates a complete breaker assembly - module-wise exploded viewis shown, in accordance with an embodiment of the present subject matter.

Figure 5 illustrates a single pole assembly - exploded view is shown, in accordance with an embodiment of the present subject matter.

Figure 6 illustrates a single pole assembly are shown, in accordance with an embodiment of the present subject matter.

Figure 7 illustrates a single pole assembly - showing feature for visual indication of shaft position are shown, in accordance with an embodiment of the present subject matter.

Figure 8 illustrates a pole and operating mechanism assembly - exploded view is shown, in accordance with an embodiment of the present subject matter.

Figure 9 illustrates the pole and operating mechanism assembly is shown, in accordance with an embodiment of the present subject matter.

Figure 10 illustrates a pole and operating mechanism assembly is shown, in accordance with an embodiment of the present subject matter.

Figure 11 illustrates a pole and operating mechanism assembly is shown, in accordance with an embodiment of the present subject matter.

Figure 12 illustrates a pole and operating mechanism assemblyis shown, in accordance with an embodiment of the present subject matter.

Figure 13 illustrates a pole and operating mechanism assembly is shown, in accordance with an embodiment of the present subject matter.

Figure 14 illustrates a chassis assembly asshown, in accordance with an embodiment of the present subject matter.

Figure 15 illustrates a chassis assembly - exploded viewis shown, in accordance with an embodiment of the present subject matter.

Figure 16 illustrates a chassis assembly assembled view shown, in accordance with an embodiment of the present subject matter.

Figure 17 illustrates a cassis assembly - mechanism movement restriction topis shown, in accordance with an embodiment of the present subject matter.

Figure 18 illustrates a cassis assembly - mechanism movement restriction bottom is shown, in accordance with an embodiment of the present subject matter.

Figure 19 illustrates a release assembly - assembly of CT links is shown, in accordance with an embodiment of the present subject matter.

Figure 20 illustrates a release assembly is shown, in accordance with an embodiment of the present subject matter.

Figure 21 illustrates a release and front cover assemblyis shown, in accordance with an embodiment of the present subject matter.

Figure 22 illustrates an aaccessory layoutis shown, in accordance with an embodiment of the present subject matter.

Figure 23 illustrates accessories insertion in chassis is shown, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION OF THE PRESENT INVNENTION

Preferred embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

The terms and words used in the following description 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.

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

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.

In one implementation, the present invention is related to an improved moulded case circuit breaker.

Accordingly, in one implementation, a molded case circuit breaker (MCCB) with a contact system (1) assembly, an operating mechanism (2) assembly, a release (3) assembly, and other parts (4) forming outer body is disclosed. The molded case circuit breaker (MCCB) comprises of at least one pole (11) assembly in the contact system (1) assembly. The operating (2) mechanism assembly comprises of a user interface, at least two shaft pins (22), at least two lower links (21), at least two mounting screws and nuts (12), at least two release side spacers (126), a TAC actuator (127), an aux actuator and an EOM actuator, a knob (23), and a chassis (42) with at least two features (423, 424). The operating mechanism (2) assembly is then assembled with the said at least one pole (11) and the knob (23) is assembled with a cover (24) for an ingress protection.

In one implementation, said at least one pole (11) assembly consists of at least two cassettes (111,112) for housing all components of the molded case circuit breaker (MCCB).

In one implementation, the contact system (1) assembly comprises at least one shaft (115) which includes a compression spring based flip locking mechanism, wherein said shaft (115) is hinged in said at least two cassettes (111, 112) allowing it to rotate along its axis.

In one implementation, the contact system (1) assembly comprises at least one nut plate (119) trapped inside said at least two cassettes (111, 112) and forms means for electrical connection along with at least one screw (118).

In one implementation, the contact system (1) assembly comprises at least one nut (120) trapped between said at least two cassettes (111, 112) that facilitates joining of the chassis (42) with said at least one pole (11) assembly.

In one implementation, at least one pole (11) assembly has a unique feature for visual indication of at least one shaft (115) position with respect to said at least two cassettes (111, 112), an arrow marking on at least one shaft (115), and a scale marking on said at least two cassettes (111, 112).

In one implementation, contact system (1) assembly comprises at least rivets (121) to rivet together said at least two cassettes (111, 112).

In one implementation, said at least two shaft pins (22) are passed through said at least two lower links (21), wherein said at least two lower links (21) form means to transfer said operating mechanism (2) assembly force to said at least one pole (11) assembly.

In one implementation, said at least one pole (11) assembly is rigidly fixed with the help of said screws (12) and said nuts (12) which further forms means for fixing said operating mechanism (2) assembly with said at least one pole (11) assembly.

In one implementation, said at least two release side spacers (126) are assembled between said at least one pole (11) assembly, to maintain clearance between said operating mechanism (2) assemblies, and said at least one pole (11) assembly.

In one implementation, said at least two release side spacers (126) is placed in between a release side fixed contact terminations (114), to provide sufficient creepage distance between said at least one pole (11) assembly.

In one implementation, the TAC actuator (127) is hinged on one of the screws (121) and engaged with said operating mechanism (2) assembly.

In one implementation, the Aux actuator and the EOM actuators forms side caps for said at least one pole (11) assembly and also work as insulating means.

In one implementation, the knob (23) is click fitted with said operating mechanism (2) assembly and acts as user interface for operating the breaker

In one implementation, the chassis (42) has features (423, 424) to arrest the movement of said operating mechanism (2) assembly.

In one implementation, the contact system (1) assembly is a current carrying path of the MCCB, wherein the contact system (1) assembly has two stable states a contacts open and a contacts close.

In one implementation, a contact system (1) forms the actual current carrying path of the breaker is shown in figure 1. It has two stable states:
a) Contacts open (not touching each other) (referred as OFF condition of breaker) and
b) Contacts close (touching each other) (ON condition of the breaker).

In one implementation, an operating mechanism (2) is used for transitioning contact system (1) states and also to keep contact system stable in one state. It consists of user interface parts those allow user to toggle between the breaker states with the help of mechanical input.

In one implementation, a release assembly (3) consists of sub-assemblies used for detecting abnormal conditions in the power system and issuing desired trip command to the operating mechanism.

In one implementation, an outer body part (4) forms the outermost structure of the breaker. They are used for covering internal parts for mechanical and electrical operator safety. Also some components are used to house accessories.

Contact system pole (11) forms the most basic assembly for a breaker. The internals of a pole are shown in figure 5.

The single pole (11) assembly consists of components as shown in the figure 7. It consists of two cassettes (111), (112) in which provisions are made to house all other components. Fixed contacts (113), (114) are assembled in respective cavities in the cassettes (112), (113) which restricts all their movements once the pole is closed.

The moving contact is contained in the shaft (115) which includes compression spring based flip locking mechanism. The Shaft is hinged in the cassettes (111), (112) allowing it to rotate along its axis. Special features (1151), (1121) are provided in the cassette and shaft for pivoting to optimize the friction of the shaft with cassettes. Shaft has features to compensate for loss (erosion) of material from contact buttons due to operations or short circuits. The moving contact contained in the shaft (115) upon rotation touches both the fixed contacts simultaneously and with rotation in reverse direction it loses contact with the fixed contacts.

Arc chutes (116) are placed such that they cover the trajectory of the moving contact rotation. Brass perforated vents (117) form the disposal path for the gases formed during arcing. Nut plate (119) is trapped inside the cassettes and it forms means for electrical connection along with screw (118). The screws (118) and (119) sandwich one fixed contact and conductor coming from release (3) and ensures required contact pressure. A nut (120) is trapped between two cassettes which facilitates joining of chassis (42) with the poles (11). After assembling all these components the two cassettes (111), (112) are riveted together with the help of two rivets (121).

After riveting complete pole assembly is formed which is self contained and can be joined together to form different configurations like 3-pole and 4-pole.

The single pole (11) has a unique feature for visual indication of shaft (115) position with respect to cassettes (111), (112). There is an arrow marking on the shaft (115) indicated by (1151) and similarly there is scale marking on cassette (111), (112) indicated by (1111). In normal conditions when breaker is in a stable condition the shaft (115) will rotate by certain fixed angle and attain its fixed position, which is visually marked on the breaker. If in any breaker the shaft is not able to reach its position, the breaker needs attention. This feature is helpful in quick analysis of breaker in case of any defects.

The operating mechanism (2) assembly is then assembled with the pole (11). Two shaft pins (22) are passed through the two lower links (21) of the operating mechanism (2). These two lower links (21) form means to transfer the operating mechanism (2) force to the pole (11).

The mechanism is then rigidly fixed on the pole (11) with the two mounting screws (12) as shown in figure 10. The mounting screws (121) are special type of screws having their shank diameter equal to thread diameter. This helps in reducing the clearances between mounting screws (121) and pole (11) / operating mechanism (2) restricting vibrations of operating mechanism (2) during operations, which may in turn result in nuisance tripping of mechanism (2). These screws are the same as of those used for connecting all poles together and needed to be removed further for assembling more poles with this assembly.

For coupling more poles (11) with this assembly two through pins (125) are assembled which pass through the shaft (115) of the pole (11) and protrude out on both the ends allowing coupling of more poles (11) from both ends. Two components (124) made of insulating material are assembled on the through pins (125) and positioned in between the two poles (11). They act as insulating barriers.

The additional poles (11) are joined from both ends and their shafts (15) are coupled together by means of through pins (125).

The shaft pins (22) are also coupled with the remaining two poles (11). As the mechanism (2) is directly coupled with all three poles (11) simultaneously any loss of rotation in any of the poles is not transferred to other pole.

These poles are then rigidly fixed with the help of four screws (1211), (1212), (1213), (1214) and nuts (1215) also two of these screws (1211), (1213) also form means for fixing operating mechanism (2) with the poles (11). Two release side spacers (126) are assembled between the poles (11), to maintain clearance between mechanism (2) and poles. Reduced clearance may result in friction of operating mechanism (2), causing loss of mechanism (2) force and operational issues. These spacers (126) also act as mechanism joining medium of contact system (1) and release (4). The spacer is placed in between the release side fixed contact terminations (114), to provide sufficient creep age distance between poles. TAC actuator (127) is hinged on one of the screws (121) and engaged with operating mechanism (2). Aux actuator and EOM actuator forms side caps for extreme poles and also works as insulating means. Knob (23) is click fitted with the operating mechanism 2 and acts as user interface for operating the breaker.

Bottom cover (41) is assembled from the bottom and fixed with the help of click fits (411) and provision for trapping nuts (412).Features (411) are provided in housing (41) which get locked with one of the multi pole joining screws (1212). The arrangement for nut trapping (412) is shown is figure 12. Bottom Cover (41) encloses contact system (1) in an insulating chamber maintaining required clearance and creep age distances from the mounting structures. The cover (41) also acts as a means for restricting movement of Aux actuator and EOM Indicator.

The knob (23) is locked with the mechanism (2) with the help of snap fit (231) as shown in figure 13. This snap fit locks knob with mechanism securing its position with the mechanism (2) when the front cover (43) is removed.

The chassis (42) is rigidly fixed on the poles (11) with the help of nuts (120) trapped inside the poles (11). Chassis (42) is contains cavities designed to house accessories like Under-voltage Release, Shunt release, Flux Shift Device (FSD) and AUX and TAC contacts. The actuators required to actuate and reset the accessories are assembled in the chassis.

The chassis (42) when assembled with the poles (11), the portion of chassis (422) gets engaged with poles (11) in forming venturi type construction in the channel for disposal of gases. This construction helps in channelizing the gases at a faster pace. Also it prevents any from gases going to termination region which may result in flash over during short circuit conditions. Release electrical connection screws (1141) join fixed contact (114) with release conductor of each pole separately. The chassis (42) has features to cover these screws (1141) so as to provide operator with protection against electrical shocks.

The chassis (42) has features (423) and (424) to arrest the movement of operating mechanism. The chassis (42) when fixed with contact system (1) restricts the motion of operating mechanism as shown in figure 16, figure 17 and figure 18.

The release assembly (3) consists of a release box (32) which forms a basic structure of assembly. The CT links (33) are fixed in the release box (32) with the help of screws (331). CT links have tapings made in them which gets engaged with screws (331) sandwiching release box (32) in between.

The sensor assemblies (37) consisting of CTs and Rogowski are assembled on the CT links (33). The Box is then enclosed with a cap (34), which is joined by means of flared inserts (321) assembled in the box (32) and screws (322). The electronic card (37) is placed in the cavity provided in the release box (32). The Release front cover (35) then covers the card (37) from top keeping access only for the user accessible parts. The flapper (36) covers the user accessible part of card (37). The flapper (36) is pivoted in the release front cover (35) such that it is free to rotate about its axis. The flapper (36) can be snap-fitted with release front Cover (35) and can be opened by rotation. The flapper (36) has provision to pass a wire which can lock flapper (36) and release front cover (35) together, restricting access to the user accessible part of the card (37).

The release assembly is then fixed with help of two screws (31) and two nuts (312). The nuts are trapped in a cavity in the bottom cover (41). The screws (31) pass through the chassis (42); the contact system spacers (126), the release assembly (4) and the bottom cover (41) and rigidly hold them together. The release assembly can be either thermal magnetic type or microprocessor based type, both can be used interchangeably.

The mechanism knob (23) is assembled with a cover (24) for ingress protection. The cover (24) is fixed with the knob using snap fits so that the (24) placement is secured and any misplacing is avoided. The front cover (43) is assembled with the help of four self tapping screws (431) which gets fixed with chassis (42) after tightening.

The nut (431) is trapped into a nut retainer (43) which can be assembled in the termination region of release (4) as well as the contact system (1), which helps in direct termination of bus bars and cable lugs. For different termination type requirement the nut retainers (43) can be replaced with other ones suitable for the termination type used. The nut retainers (43) are click fitted with the assembly.

The release front cover (35) has features (361) shown in figure 21, which gets interlocked with the front cover (43). This feature provides safety interlock such that the internal live parts of the release cannot be accessed without removing the front cover (43).

As shown in figure 22, in Chassis (42) is designed for mounting accessories. The two cavities (422) are for under-voltage and shunt release. Both cavities are identical and UV or Shunt can assembled interchangeably in those. The cavity (423) is for flux shifting device used as a tripping medium along with microprocessor based release. Three cavities are provided for Auxiliary Contacts and can be used interchangeably. The cavity (425) can house a TAC contact in it.

The figure 23 shows the assembly of some accessories. The UV or shunt release (45) is fixed with the help of snap fit and a screw. The auxiliary contacts (46) are assembled in the chassis with the help of a snap fit.

Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include those provided by the following features:

One feature of the invention is that, a visual indication of shaft position with respect to cassette is provided for easy detection of any faults in pole assembly

Another feature of the invention is that, a cassette is provided with special features for pivoting the shaft to minimize the friction.

Another feature of the invention is that, the feature provided in the invention also forms poka-yoke for wrong assembly of the shaft.

Another feature of the invention is that, the metallic vent is provided that helps in de-ionizing the gases going out of the pole.

Another feature of the invention is that, a nut is trapped between the cassettes which forms means for mounting chassis.

Another feature of the invention is that, the operating mechanism is directly coupled with minimum three Poles avoiding transmission of rotation loss from one pole to another.

Another feature of the invention is that, the shafts are coupled together by means of two through pins which are coupled with operating mechanism by an insulating coupler which also ensures electrical insulation of mechanism.

Another feature of the invention is that, the invention use of two pole connection screws out of four for operating mechanism fixing with the poles.

Another feature of the invention is that, the invention uses a special type of screws to restrict operating mechanism vibrations.

Another feature of the invention is that, the knob is fixed with the mechanism fork by a strong snap fit such that even after removal of front cover it will not fall off.

Another feature of the invention is that, the release side spacers 126 acts as a spacer, and the release mechanical joining means and also maintaining creep age between the contacts.

Another feature of the invention is that, the bottom cover encloses contact system in an insulating chamber isolating it from mounting structure and maintaining required clearance and creep age distances.

Another feature of the invention is that, the bottom cover is used to enclose the contact system 1 such that any gases should not escape from any area other than vents.

Another feature of the invention is that, the bottom cover is fixed with contact system using two snap-fits on bottom cover ribs, which interlocks with multi-pole mounting screws.

Another feature of the invention is that, the bottom cover also forms guidance for the movement of Aux actuator and EOM Indicator.

Another feature of the invention is that, the chassis forms the venturi type construction in gas disposal path helping in channelizing of gases at a faster pace

Another feature of the invention is that, the release electrical connection screw is covered by chassis for operator safety.

Another feature of the invention is that, the 2 under-voltage or shunt releases can be used interchangeably and independently in any combination in any cavity.

Another feature of the invention is that, the chassis when fixed with contact system restricts any movement of the operating mechanism.

Another feature of the invention is that, the TAC actuator is pivoted on a pole joining screw.

Another feature of the invention is that, the AUX actuator and EOM indicator forms through pin caps from both extreme ends providing additional insulation.

Yet another feature of the invention is that, the release joining screw combines chassis, release, contact system and bottom cover together.

Yet another feature of the invention is that, the extended knob forms safety interlock feature restricting removal of Front Cover in ON and OFF conditions and allowing removal only in TRIP condition.

Yet another feature of the invention is that, the release front cover is interlocked with breaker front cover such that live parts inside the release assembly cannot be accessed with breaker in ON condition.

Yet another feature of the invention is that, the cover of the knob is fixed with knob by means of snap fits so that there placement is secured and any misplacing is avoided.

Still another feature of the invention is that, the breaker has provision to mount auxiliary contacts and 1 trip alarm contact simultaneously.

Still another feature of the invention is that, the 3 AUX switches can be used interchangeably and independently in any combination in any cavity

Although an improved moulded case circuit breaker has 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 improved moulded case circuit breaker.
,CLAIMS:1. A molded case circuit breaker (MCCB) with a contact system (1) assembly, an operating mechanism (2) assembly, a release (3)assembly, and other parts (4) forming outer body, the molded case circuit breaker (MCCB) comprising:
at least one pole (11) assembly in the contact system (1) assembly;
the operating (2) mechanism assembly comprising a user interface, at least two shaft pins (22), at least two lower links (21), at least two mounting screws and nuts(12), at least two release side spacers (126), a TAC actuator (127), an aux actuator and an EOM actuator, a knob (23), and a chassis (42) with at least two features (423, 424), wherein the operating mechanism (2) assembly is then assembled with the said at least one pole (11) and the knob (23) is assembled with a cover (24) for an ingress protection.

2. The molded case circuit breaker (MCCB) as claimed in claim 1, wherein said at least one pole (11) assembly consists of at least two cassettes (111,112) for housing all components of the molded case circuit breaker (MCCB).

3. The molded case circuit breaker (MCCB) as claimed in claim 1 and 2, wherein the contact system (1) assembly comprises at least one shaft (115) which includes a compression spring based flip locking mechanism, wherein said shaft (115) is hinged in said at least two cassettes (111, 112) allowing it to rotate along its axis.

4. The molded case circuit breaker (MCCB) as claimed in claim 1 to 3, wherein the contact system (1) assembly comprises at least one nut plate (119) trapped inside said at least two cassettes (111,112) and forms means for electrical connection along with at least one screw (118).
5. The molded case circuit breaker (MCCB) as claimed in claim 1 to 4, wherein said contact system (1) assembly comprises at least one nut (120) trapped between said at least two cassettes (111,112) that facilitates joining of the chassis (42) with said at least one pole (11) assembly.

6. The molded case circuit breaker (MCCB) as claimed in claim 1 to 5, wherein said contact system (1) assembly comprises at least rivets (121) to rivet together said at least two cassettes (111,112).

7. The molded case circuit breaker (MCCB) as claimed in claim 1 to 6, wherein said at least one pole (11) assembly has a unique feature for visual indication of at least one shaft (115) position with respect to said at least two cassettes (111,112), an arrow marking on at least one shaft (115), and a scale marking on said at least two cassettes (111,112).

8. The molded case circuit breaker (MCCB) as claimed in claim 1 to 7, wherein said at least two shaft pins (22) are passed through said at least two lower links (21), wherein said at least two lower links (21) form means to transfer said operating mechanism (2) assembly force to said at least one pole (11) assembly.

9. The molded case circuit breaker (MCCB) as claimed in claim 1 to 8, wherein said at least one pole (11) assembly is rigidly fixed with the help of said screws (12) and said nuts (12)which further forms means for fixing said operating mechanism (2) assembly with said at least one pole (11) assembly.

10. The molded case circuit breaker (MCCB) as claimed in claim 1 to 9, wherein said at least two release side spacers (126) are assembled between said at least one pole (11) assembly, to maintain clearance between said operating mechanism (2) assemblies, and said at least one pole (11) assembly.

11. The molded case circuit breaker (MCCB) as claimed in claim 1 to 10, wherein said at least two release side spacers (126) is placed in between a release side fixed contact terminations (114), to provide sufficient creepage distance between said at least one pole (11) assembly.

12. The molded case circuit breaker (MCCB) as claimed in claim 1 to 11, wherein the TAC actuator (127) is hinged on one of the screws (121) and engaged with said operating mechanism (2) assembly.

13. The molded case circuit breaker (MCCB) as claimed in claim 1 to 12, wherein the Aux actuator and the EOM actuators forms side caps for said at least one pole (11) assembly and also work as insulating means.

14. The molded case circuit breaker (MCCB) as claimed in claim 1 to 13, wherein the knob (23) is click fitted with said operating mechanism (2) assembly and acts as user interface for operating the breaker.

15. The molded case circuit breaker (MCCB) as claimed in claim 1 to 14, wherein the chassis (42) has features (423, 424) to arrest the movement of said operating mechanism (2) assembly.

16. The molded case circuit breaker (MCCB) as claimed in claim 1 to 14, wherein the contact system (1) assembly is a current carrying path of the MCCB, wherein the contact system (1) assembly has two stable states a contacts open and a contacts close.