A) TECHNICAL FIELD

[1] The present invention generally relates to circuit breakers and particularly to thermo-magnetic release in circuit breaker devices such as molded case circuit breaker (MCCB) devices. The present invention more particularly relates to a wide range overload setting unit with multiple bimetals for thermo-magnetic release in molded case circuit breaker.

B) BACKGROUND OF THE INVENTION

[2] The electrical circuit breakers are well known and have been employed for many years to control the flow of electrical current in serially connected electrical circuits. The circuit breakers are switches that open in response to prolonged overload or short-circuit current. The contacts are mechanically closed against the action of a heavy spring and held closed by a latch. Circuit breakers are manually or automatically opened or tripped by the external signals that are typically output from some type of protective relays. The most common relay used in the protection of the power distribution system is an over current relay. The function of the relay is to sense the over current in the system and to provide the circuit breaker tripping operation.

[3] The overload tripping is used to allow a circuit breaker to protect the system components such as transformers, motors, conductors etc,, which may fail due to the restrictive heating. The trip unit is the brain of the circuit breaker. The function of the trip unit is to trip the operating mechanism in the event of a short circuit or a prolonged overload current condition. The traditional molded case circuit breakers use electromechanical or thermal magnetic trip units. The protection is provided by combining a temperature sensitive device with a current sensitive electromagnetic device, both of which act mechanically on the trip mechanism.

[4] The Molded case circuit breakers are available in several types. The thermal-magnetic type is the one most commonly used. The thermal overload release operates by means of a bimetallic element, in which the current flowing through the conducting path of a circuit breaker generates heat in the bi-metal element, which causes the bi-metal to deflect and trip the breaker. The heat generated in the bi-metal is a function of the amount of current passed through the bi-metal as well as the period of time for which the current is passed through. The amount of current needed to trip the circuit breaker depends on the size of the gap between the trip bar and the magnetic element. In some circuit breakers, this gap is adjustable.

[5] In a conventional the thermo magnetic release, the overload current settings are available from 63% of its rated current capacity but it is not possible to adjust the overload settings for a lower current range below 40%. In a rapidly growing industry, the load on the circuit breaker goes on increasing due to the installation of new equipment. In this case, the older circuit breakers cannot be used for adjusting the range of the installed loads. Hence there is a need to provide an overload setting unit for adjusting the load over wide range i.e. from 40% to 100% of its rated current.

[6] Moreover, the assembling of the various parts in the adjusting mechanism is very complex and requires lot of effort to manufacture the overload setting unit in the currently available thermo-magnetic release for circuit breaker. Hence there is a need to provide a simple over load setting unit for thermo-magnetic release in molded case circuit breaker for adjusting the load over wide range during overload condition.

[7] The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.

C) OBJECTS OF THE INVENTION

[8] The primary object of the present invention is to provide a wide range overload setting unit with multiple bimetals for thermo-magnetic release in a molded case circuit breaker.

[9] Yet another object of the present invention is to develop an overload setting unit for molded case circuit breakers to increase the overall range of the overload setting conditions by using multiple bimetal of different characteristics such as deflection, linearity and maximum operating temperature etc.

[10] Yet another object of the present invention is to provide an overload setting unit with two thermo magnetic releases that are operated lower current range and in higher current range respectively.

[11] Yet another object of the present invention is to provide a wide range overload setting unit with simple structures thereby reducing the assembly time during the manufacturing process.

[12] Yet another object of the present invention is to provide an overload setting unit for thermo-magnetic release in MCCB with an overload current setting in the range of 40% to 100% of its rated current.

[13] Yet another object of the present invention is to develop a wide range overload condition setting unit provided with sliders for adjusting the deflection of the bimetals during the high range and low range over load conditions.

[14] Yet another object of the present invention is to develop a wide range overload condition setting unit that is used as a safety device for sensing over current conditions.

[15] 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.

D) SUMMARY OF THE INVENTION
[16] The various embodiments of the present invention provide a wide range overload setting unit with multiple bimetals for thermo-magnetic release in molded case circuit breaker.

[17] According to one embodiment of the present invention, a wide range over load adjustment mechanism with multiple bimetals for thermo magnetic release in circuit breaker has a first slider mechanism and a second slider mechanism which is coupled to the first slider mechanism. An actuating knob is connected to both the first slider mechanism and the second slider mechanism. A heater is provided in the circuit breaker. A trip plate is provided in the circuit breaker. A first bimetal and a second bimetal are connected to the heater and the trip plate.

[18] The actuating knob is rotated to adjust the effective distance between the first slider mechanism and the first bimetal to activate the first slider mechanism in low range over load conditions for adjusting the over load setting in low ranges and to adjust the effective distance between the second slider mechanism and the second bimetal to activate the second slider mechanism and to deactivate the first slider mechanism in high range over load conditions for adjusting the over load setting in high ranges. The actuating knob is rotated in clock wise direction to activate the first slider mechanism to deflect the first bimetal to activate the trip plate during the low range overload conditions while the actuating knob is rotated further in clock wise direction to activate the second slider mechanism to deflect the second bimetal to activate the trip plate and to deactivate the first slider mechanism during the high range overload conditions.

[19] The first slider mechanism is an auxiliary slider mechanism. The second slider mechanism is a main slider mechanism. The first bimetal is a high sensitivity bimetal. The second bimetal is a low sensitivity bimetal. The first bimetal and the second bimetal have mutually different specific deflection, thermal conductivity and linearity range. The first bimetal is active during low range over voltage conditions, The second bimetal is active during high range over voltage conditions. The actuating knob is an adjustment knob for overload setting.

[20] The actuating knob is rotated in clock wise direction to move the first slider mechanism linearly over the second slider mechanism to activate the first slider mechanism to adjust the effective distance between the first bimetal and the first slider mechanism to adjust the overload setting in low range so that the deflection of the first bimetal is used to activate the trip plate in low range overload conditions. The actuating knob is rotated further in clock wise direction to make the second slider mechanism move linearly along with the first slider mechanism to activate the second slider mechanism and to deactivate the first slider mechanism to adjust the effective distance between the second bimetal and the second slider mechanism to adjust the overload setting in high range so that the deflection of the second bimetal is used to activate the trip plate in high range overload conditions.

[21 ] Each pole has a set of first bimetal and a second bimetal. Each pole has a heater connected to both the first bimetal and a second bimetal. The first slider mechanism and the second slider mechanism are provided in common to all the poles in a circuit breaker. A compression spring is connected to the second slider mechanism and to a cover plate in the circuit breaker housing to bring back the sliders to the original position. The compression springs are compressed and charged during the clock wise rotation of the actuating knob. The actuating knob is rotated in anti clockwise direction to release the compression spring to move the first slider mechanism and the second slider mechanism to the original position using the stored energy in the compression spring.

[22] According to one embodiment of the present invention, the overload setting unit mainly comprises of a pair of bimetal (bimetal-1 and bimetal-2), heater, pair of slider (slider-1 and slider-2), a compression spring and an actuating knob for adjusting the effective gap between the bimetal and the slider to trip the molded case circuit breaker.

[23] According to one embodiment of the present invention, the slider-1 is housed in the horizontal protrusions in the slider-2. The two sliders slider-1 and slider-2 acts as a trip plate each working for different current range and is operated using a single actuating knob. An actuating knob is inserted between the two horizontal protrusions in the slider-1. The effective distance between the sliders is adjusted by rotating the operating knob which in turn lead to the adjustment of the overload setting in lower and higher current range. The two sliders are designed for varying the effective length between the bimetals and the trip liver. During overload setting, the slider either increases or decreases the deflection required by the bi-metal to trip the breaker depending on the direction of motion of the actuation knob. The deflection of bimetal is based on the temperature generated by the heater. When the MCCB is overloaded the current passing through the heater increases which in turn increases the amount of heat produced by the heater. Some part of this energy is absorbed by the bimetal and the bimetal gets deflected from its original dimensions. A high specific deflection bimetal is used for low current and the low specific deflection bimetal is used for high current settings. These bimetals can also be used interchangeably.

[24] When the MCCB is overloaded the bimetal-1 which is in active state hits the slider-1 and the slider-1 in turn makes the circuit breaker to trip. When the actuation knob is rotated in clockwise direction the slider-1 will be in operating condition. In this position, the bimetal-1 which is in active state hits the slider-1. When the actuating knob is rotated manually the slider-1 slide over slider-2 for some linear distance without disturbing slider-2 during this period bimetal-1 is in active state and the effective distance between the bimetal-1 and slider-1 is adjusted which in turn leads to the adjustment of the over load setting in lower range later when the knob is further rotated the slider-2 also starts moving linearly along with the slider-1 in this state only slider-2 is in active state and slider-1 goes to its inactive state here the effective distance between the bimetal-2 and the slider-2 is adjusted which in turn leads to the adjustment of the overload setting in the higher range. When the slider-2 is in active state, the slider-1 which was in-active state automatically gets deactivated. Now the bimetal-2 goes to active state and hits the slider-2. When the knob is rotated in the anti-clockwise direction the compression spring brings back the sliders to the original position. In all the above cases the linear displacement of the slider is dependent on the rotary motion of the knob.

[25] According to one embodiment of the present invention, an overload setting unit is designed for 3 pole operation of circuit breaker it is also for single pole circuit breaker. The overload setting unit for three pole circuit breaker comprises of 3 heaters (one per pole), 6 bimetals (2 per pole) and one actuating knob per pole for adjusting the overload settings. The effective distance between the bimetal and slider is adjusted by using actuation knob to adjust the over load setting in lower and higher current range.

[26] The overload setting unit is also used as a safety device for over current sensing. The thermal assembly in thermo-magnetic release for molded case circuit breaker is such that it can be manufactured for two releases one with extended current range and the other with lower current range . The overload setting unit can be used for single pole as well as 3 pole circuit breakers. The assembling of the various parts in the overload setting unit is very simple and hence can be manufactured with less effort.

E) BRIEF DESCRIPTION OF THE DRAWINGS

[27] 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:

[28] FIG, 1 shows a perspective view of a first slider mechanism in a wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention.

[29] FIG. 2 shows a perspective view of a second slider mechanism in a wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention.

[30] FIG. 3 shows an exploded perspective view of the sliders assembly in a wide range overload adjustment mechanism with multiple bimetals for thermo- magnetic release in circuit breaker devices, according to one embodiment of the present invention.

[31] FIG. 4 shows a perspective of the sliders assembly in a wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention, with the first slider mechanism in active condition.

[32] FIG. 5 shows a perspective of the sliders assembly in a wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention, with the second slider mechanism in active condition and the first slider mechanism in non-active condition.

[33] FIG. 6 shows a top side perspective view of the wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention, with the first slider mechanism in active condition.

[34] FIG, 7 shows a top side perspective view of the wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention, with the second slider mechanism in active condition and the first slider mechanism in non- active condition.

[35] FIG. 8 shows a top side perspective view of the wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention, with the compression spring and the first and the second slider mechanisms in original position.

[36] FIG. 9 shows a top side perspective view of the 3 pole molded case circuit breaker with wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release according to one embodiment of the present invention.

[37] Although 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

[38] In the following detailed description, 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.

[39] The various embodiments of the present invention provide a wide range overload setting unit with multiple bimetals for thermo-magnetic release in molded case circuit breaker. According to one embodiment of the present invention, a wide range over load adjustment mechanism with multiple bimetals for thermo magnetic release in circuit breaker has a first slider mechanism and a second slider mechanism which is coupled to the first slider mechanism. An actuating knob is connected to both the first slider mechanism and the second slider mechanism. A heater is provided in the circuit breaker. A trip plate is provided in the circuit breaker. A first bimetal and a second bimetal are connected to the heater and the trip plate,

[40] The actuating knob is rotated to adjust the effective distance between the first slider mechanism and the first bimetal to activate the first slider mechanism in low range over load conditions for adjusting the over load setting in low ranges and to adjust the effective distance between the second slider mechanism and the second bimetal to activate the second slider mechanism and to deactivate the first slider mechanism in high range over load conditions for adjusting the over load setting in high ranges. The actuating knob is rotated in clock wise direction to activate the first slider mechanism to deflect the first bimetal to activate the trip plate during the low range overload conditions while the actuating knob is rotated further in clock wise direction to activate the second slider mechanism to deflect the second bimetal to activate the trip plate and to deactivate the first slider mechanism during the high range overload conditions.

[41 ] The first slider mechanism is an auxiliary slider mechanism. The second slider mechanism is a main slider mechanism. The first bimetal is a high sensitivity bimetal. The second bimetal is a low sensitivity bimetal. The first bimetal and the second bimetal have mutually different specific deflection, thermal conductivity and linearity range. The first bimetal is active during low range over voltage conditions. The second bimetal is active during high range over voltage conditions. The actuating knob is an adjustment knob for overload setting.

[42] The actuating knob is rotated in clock wise direction to move the first slider mechanism linearly over the second slider mechanism to activate the first slider mechanism to adjust the effective distance between the first bimetal and the first slider mechanism to adjust the overload setting in low range so that the deflection of the first bimetal is used to activate the trip plate in low range overload conditions. The actuating knob is rotated further in clock wise direction to make the second slider mechanism move linearly along with the first slider mechanism to activate the second slider mechanism and to deactivate the first slider mechanism to adjust the effective distance between the second bimetal and the second slider mechanism to adjust the overload setting in high range so that the deflection of the second bimetal is used to activate the trip plate in high range overload conditions.

[43] Each pole has a set of first bimetal and a second bimetal. Each pole has a heater connected to both the first bimetal and a second bimetal. The first slider mechanism and the second slider mechanism are provided in common to all the poles in a circuit breaker. A compression spring is connected to the second slider mechanism and to a cover plate in the circuit breaker housing to bring back the sliders to the original position. The compression springs are compressed and charged during the clock wise rotation of the actuating knob, The actuating knob is rotated in anti clockwise direction to release the compression spring to move the first slider mechanism and the second slider mechanism to the original position using the stored energy in the compression spring.

[44] According to one embodiment of the present invention, a wide range overload setting unit is provided with multiple bimetals for thermo-magnetic release in molded case circuit breaker. The overload setting unit mainly comprises of a pair of bimetal (bimetal-1 and bimetal-2), heater, pair of slider (slider-1 and slider-2), a compression spring and an actuating knob for adjusting the effective gap between the bimetal and the slider to trip the molded case circuit breaker. According to one embodiment, an overload setting unit is designed for 3 pole operation of circuit breaker it includes 3 heaters (one per pole), 6 bimetals (2 per pole) and one actuating knob per pole for adjusting the overload settings.
[45] According to one embodiment of the present invention, the slider-1 is housed in the horizontal protrusion in the slider-2. The two sliders slider-1 and slider-2 acts as a trip plate each working for different current range and is operated using a single actuating knob. An actuating knob is inserted between the two horizontal protrusions in the slider-1. The effective distance between the sliders is adjusted by rotating the operating knob which in turn lead to the adjustment of the overload setting in lower and higher current range. The two sliders are designed for varying the effective length between the bimetals and the trip liver. During overload setting, the slider either increases or decreases the deflection required by the bi-metal to trip the breaker depending on the direction of motion of the actuation knob. The deflection of bimetal is based on the temperature generated by the heater. When the molded case circuit breaker (MCCB) is overloaded, the current passing through the heater increases which in turn increases the amount of heat produced by the heater. Some part of this energy is absorbed by the bimetal and the bimetal gets deflected from its original dimensions. A high specific deflection bimetal is used for low current and the low specific deflection bimetal is used for high current settings. These bimetals can also be used interchangeably.

[46] When the MCCB is overloaded the bimetal-1 which is in active state hits the slider-1 and the slider-1 in turn makes the circuit breaker to trip. When the actuation knob is rotated in clockwise direction the slider-1 will be in operating condition. In this position, the bimetal-1 which is in active state hits the slider-1. When the actuating knob is rotated manually the slider-1 slide over slider-2 for some linear distance without disturbing slider-2, during this period bimetal-1 is in active state and the effective distance between the bimetal-1 and slider-1 is adjusted which in turn leads to the adjustment of the over load setting in lower range later when the knob is further rotated the slider-2 also starts moving linearly along with the slider-1 in this state only slider-2 is in active state and slider-1 goes to its inactive state here the effective distance between the bimetal-2 and the slider-2 is adjusted which in turn leads to the adjustment of the overload setting in the higher range. When the slider 2 is in active state and the slider-1 which was in-active stage automatically gets deactivated, Now the bimetal-2 goes to active state and hits the slider when the MCCB becomes overloaded. When the knob is rotated in the anti-clockwise direction the compression spring brings back the sliders to the original position. In all the above cases the linear displacement of the slider is dependent on the rotary motion of the knob.

[47] The overload setting unit can be used as a safety device for over current sensing. The thermal assembly in thermo-magnetic release for molded case circuit breaker is such that it can be manufactured for two releases one with extended current range and the other with lower current range . The overload setting unit can be used for single pole as well as 3 pole circuit breakers. The assembling of the various parts in the overload setting unit is very simple and hence can be manufactured with less effort.
[48] FIG. 1 shows a perspective view of a first slider mechanism in a wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention. With respect to FIG. 1, the first slider mechanism 10 is an auxiliary slider mechanism. The first slider mechanism 10 has a base frame 11 mounted with three contact projections 12, 13, 14. The three projections 12-14 are protruded from one side surface of the base frame 11. Two 12, 14 of the three contact projections 12-14 are provided at both the ends of the base frame 11 respectively. The remaining third projection 13 is arranged at the middle of the base frame 11. The three projections 12-14 act as contact points for the bimetals. Two finger-like projections 15, 16 are formed to protrude from the other side surface of the base frame 11. The two finger- like projections 15, 16 are formed at the middle portion of the base frame 11 and are separated from each other to form a gap to receive an actuating knob which is used for adjusting the overload setting. The first slider mechanism 10 is provided in common to all the three poles in a circuit breaker.

[49] FIG. 2 shows a perspective view of a second slider mechanism in a wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention. With respect to FIG.l, the second slider mechanism 20 is a main slider mechanism. The second slider mechanism 20 has a base frame 21 mounted with three legs 22 at the bottom portion. The base frame 21 has three contact projections 23, 24, 25. The three contact projections 23-25 are protruded from one side surface of the base frame 21. Two 23, 25 of the three contact projections 23-25 are provided at both the ends of the base frame 21 respectively. The remaining third contact projection 24 is arranged at the middle of the base frame 21. The three projections 23-25 act as contact points for the bimetals. Two U-shaped projections 26, 27 with slots are formed to protrude from the other side surface of the base frame. The two U-shaped projections 26, 27 are formed at the middle portion of the base frame 2land are separated from each other. A support projection 28 is formed on the top side of the base frame 21. The second slider mechanism 20 is provided in common to all the three poles in a circuit breaker.

[50] FIG. 3 shows an exploded perspective view of the sliders assembly in a wide range overload adjustment mechanism with multiple bimetals for thermo- magnetic release in circuit breaker devices, according to one embodiment of the present invention. With respect to FIG. 3, the first slider mechanism 10 is movably supported in the second slider mechanism 20. The first slider mechanism 10 act as an auxiliary slider mechanism. The second slider mechanism 20 act as a main slider mechanism. The slider assembly containing the first slider mechanism 10 and the second slider mechanism 20 is provided in common to all the three poles in a circuit breaker device. Both the first slider mechanism 10 and the second slider mechanism 20 are operated using a single knob. The first slider mechanism 10 and the slider mechanism 20 decrease or increase the deflection required by the bimetal to trip the circuit breaker depending on the motion of the knob or the overload setting condition. The first slider mechanism 10 is kept in active condition and the second slider mechanism 20 is kept in non active condition during the adjustment of the over load setting in the lower range. The second slider mechanism 20 is kept in active condition and the first slider mechanism 10 is kept in non active condition during the adjustment of the over load setting in the higher range. The first slider mechanism 10 is used to activate the trip plate in low overload conditions. The second slider mechanism 20 is used to activate the trip plate in high overload conditions.

[51] FIG, 4 shows a perspective of the sliders assembly in a wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention, with the first slider mechanism in active condition. With respect to FIG. 4, the first slider mechanism is movably supported in the second slider mechanism. The first slider mechanism act as an auxiliary slider mechanism. The second slider mechanism act as a main slider mechanism. The slider assembly containing the first slider mechanism and the second slider mechanism is provided in common to all the three poles in a circuit breaker device. The first slider mechanism is received in the recess between the contact projections 23-25 of the second slider mechanism and the base frame 21 of the second slider mechanism. The base frames 11,21 of the first slider mechanism and the second slider mechanism are arranged adjacent to each other. An actuating knob 30 for adjusting the over load setting is received in the gap formed between the two finger like projections 15,16 provided in the base frame 11 at the first slider mechanism. Both the first slider mechanism and the second slider mechanism are operated using the single actuating knob 30 for adjusting the overload setting. The first slider mechanism and the slider mechanism decrease or increases the deflection required by the bimetal to trip the circuit breaker depending on the motion of the knob 30 for the overload setting condition. The first slider mechanism is kept in active condition and the second slider mechanism is kept in non active condition during the adjustment of the over load setting in the lower range. The second slider mechanism is kept in active condition and the first slider mechanism is kept in non active condition during the adjustment of the over load setting in the higher range. The first slider mechanism is used to activate the trip plate in low overload conditions. The second slider mechanism is used to activate the trip plate in high overload conditions,

[52] The actuating knob 30 is rotated in clock wise direction to move the first slider mechanism linearly over the second slider mechanism to activate the first slider mechanism to adjust the effective distance between the first bimetal and the first slider mechanism to adjust the overload setting in low range so that the deflection of the first bimetal is used to activate the trip plate in low range overload conditions. The actuating knob 30 is rotated further in clock wise direction to make the second slider mechanism move linearly along with the first slider mechanism to activate the second slider mechanism and to deactivate the first slider mechanism to adjust the effective distance between the second bimetal and the second slider mechanism to adjust the overload setting in high range so that the deflection of the second bimetal is used to activate the trip plate in high range overload conditions. The actuating knob 30 is rotated in anti clockwise direction to move back the first slider mechanism and the second slider mechanism to the original position using a compression spring.

[53] With respect to FIG.4, The first slider mechanism is made active and the second slider mechanism is made non active to adjust the effective distance between the bimetals and the contact projections to adjust the overload setting in low range overload conditions. The contact projections 12-14 of the first slider mechanism are arranged adjacent to the contact projections 23-25 of the second slider mechanism to make contact with the first bimetals to activate a trip plate in the circuit breaker.

[54] FIG. 5 shows a perspective of the sliders assembly in a wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention, with the second slider mechanism in active condition and the first slider mechanism in non-active condition. With respect to FIG. 5, the first slider mechanism is movably supported in the second slider mechanism. The first slider mechanism act as an auxiliary slider mechanism. The second slider mechanism act as a main slider mechanism. The slider assembly containing the first slider mechanism and the second slider mechanism is provided in common to all the three poles in a circuit breaker device. The first slider mechanism is received in the recess between the contact projections 23-25 of the second slider mechanism and the base frame 21 of the second slider mechanism. The base frames 11, 21 of the first slider mechanism and the second slider mechanism are arranged adjacent to each other. An actuating knob 30 for adjusting the over load setting is received in the gap formed between the two finger like projections provided in the base frame at the first slider mechanism. Both the first slider mechanism and the second slider mechanism are operated using the single actuating knob 30 for adjusting the overload setting. The first slider mechanism and the slider mechanism decrease or increases the deflection required by the bimetal to trip the circuit breaker depending on the motion of the knob or the overload setting condition. The first slider mechanism is kept in active condition and the second slider mechanism is kept in non active condition during the adjustment of the over load setting in the lower range. The second slider mechanism is kept in active condition and the first slider mechanism is kept in non active condition during the adjustment of the over load setting in the higher range. The first slider mechanism is used to activate the trip plate in low overload conditions. The second slider mechanism is used to activate the trip plate in high overload conditions.

[55] The actuating knob 30 is rotated in clock wise direction to move the first slider mechanism linearly over the second slider mechanism to activate the first slider mechanism to adjust the effective distance between the first bimetal and the first slider mechanism to adjust the overload setting in low range so that the deflection of the first bimetal is used to activate the trip plate in low range overload conditions. As shown in the FIG.5, the actuating knob 30 is rotated further in clock wise direction to make the second slider mechanism move linearly along with the first slider mechanism to activate the second slider mechanism and to deactivate the first slider mechanism to adjust the effective distance between the second bimetal and the second slider mechanism to adjust the overload setting in high range so that the deflection of the second bimetal is used to activate the trip plate in high range overload conditions.

[56] With respect to FIG.5. The second slider mechanism is made active and the first slider mechanism is made non active to adjust the effective distance between the bimetals and the contact projections to adjust the overload setting in high range overload conditions. The contact projections 12-14 of the first slider mechanism are arranged behind the contact projections 23-25 of the second slider mechanism so that the contact projections 23-25 of the second slider mechanism are made to contact the second bimetals to activate a trip plate in the circuit breaker.

[57] FIG. 6 shows a top side perspective view of the wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention, with the first slider mechanism in active condition. With respect to FIG.6, a wide range over load adjustment mechanism with multiple bimetals for thermo magnetic release in circuit breaker has a first slider mechanism and a second slider mechanism which is coupled to the first slider mechanism. An actuating knob 30 is connected to both the first slider mechanism and the second slider mechanism. A heater 40 is provided in the circuit breaker. A trip plate is provided in the circuit breaker. A first bimetal 50 and a second bimetal 60 are connected to the heater 40 and the trip plate.

[58] The actuating knob 30 is rotated to adjust the effective distance between the first slider mechanism and the first bimetal to activate the first slider mechanism in low range over load conditions for adjusting the over load setting in low ranges and to adjust the effective distance between the second slider mechanism and the second bimetal to activate the second slider mechanism and to deactivate the first slider mechanism in high range over load conditions for adjusting the over load setting in high ranges. The actuating knob 30 is rotated in clock wise direction to activate the first slider mechanism to deflect the first bimetal 50 to activate the trip plate during the low range overload conditions while the actuating knob 30 is rotated further in clock wise direction to activate the second slider mechanism to deflect the second bimetal 60 to activate the trip plate and to deactivate the first slider mechanism during the high range overload conditions.

[59] The first slider mechanism is an auxiliary slider mechanism. The second slider mechanism is a main slider mechanism. The first bimetal 50 is a high sensitivity bimetal. The second bimetal 60 is a low sensitivity bimetal. The first bimetal 50 and the second bimetal 60 have mutually different specific deflection, thermal conductivity and linearity range. The first bimetal 50 is active during low range over voltage conditions. The second bimetal 60 is active during high range over voltage conditions. The actuating knob 30 is an adjustment knob for overload setting.

[60] The actuating knob 30 is rotated in clock wise direction to move the first slider mechanism linearly over the second slider mechanism to activate the first slider mechanism to adjust the effective distance between the first bimetal 50 and the first slider mechanism to adjust the overload setting in low range so that the deflection of the first bimetal 50 is used to activate the trip plate in low range overload conditions. The actuating knob 30 is rotated further in clock wise direction to make the second slider mechanism move linearly along with the first slider mechanism to activate the second slider mechanism and to deactivate the first slider mechanism to adjust the effective distance between the second bimetal 60 and the second slider mechanism to adjust the overload setting in high range so that the deflection of the second bimetal 60 is used to activate the trip plate in high range overload conditions.

[61] Each pole has a set of first bimetal 50 and a second bimetal 60. Each pole has a heater 40 connected to both the first bimetal 50 and a second bimetal 60. The first slider mechanism and the second slider mechanism are provided in common to all the poles in a circuit breaker. A compression spring is connected to the second slider mechanism and to a cover plate in the circuit breaker housing to bring back the sliders to the original position. The compression springs are compressed and charged during the clock wise rotation of the actuating knob. The actuating knob is rotated in anti clockwise direction to release the compression spring to move the first slider mechanism and the second slider mechanism to the original position using the stored energy in the compression spring.

[62] The two sliders are designed for varying the effective length between the bimetals and the trip liver. A high specific deflection bimetal 50 is used for low current and the low specific deflection bimetal 60 is used for high current settings. The bimetals 50,60 are also used interchangeably.

[63] With respect to FIG.6, the first slider mechanism is under active condition and the second slider mechanism is under non active condition. The contact projections of the first slider mechanism are made to contact the first bimetal 50 so that the first bimetal 50 is deflected to contact the trip plate in the circuit breaker device. The first slider mechanism is moved to adjust the effective distance between the contact projections 12-14 and the first bimetal 50 to adjust the overload setting in the low range over load conditions.

[64] The deflection of bimetal 50 is based on the temperature generated by the heater 40. The heater 40 is a current carrying part, When the MCCB is overloaded the current passing through the heater 40 increases which in turn increases the amount of heat produced by the heater 40. Some part of this energy is absorbed by the bimetal 50, 60 and the bimetal 50, 60 gets deflected from its original dimensions. The overload adjusting is done by considering the deflection of bimetal 50, 60 and by changing the effective distance between the slider and the bimetal 50, 60 to trip the MCCB.

[65] When the MCCB is overloaded the bimetal 50 which is in active state hits the first slider and the first slider in turn makes the circuit breaker to trip. When the actuation knob 30 is rotated the first slider is in operating condition. In this position, the bimetal 50 which is in active state hits the first slider. When the actuating knob 30 is rotated manually the first slider slides over the second slider for some linear distance without disturbing the second slider. During this period the first bimetal 50 is in active state and the effective distance between the first bimetal 50 and the first slider is adjusted which in turn leads to the adjustment of the over load setting in lower range. Later when the actuation knob 30 is further rotated the second slider also starts moving linearly along with the first slider in this state only the second slider is in active state and first slider goes into its inactive state thereby adjusting the effective distance between the second bimetal 60 and the second slider which in turn leads to the adjustment of the overload setting in the higher range.

[66] FIG. 7 shows a top side perspective view of the wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention, with the second slider mechanism in active condition and the first slider mechanism in non- active condition. With respect to FIG.7, the contact projections 12-14 of the first slider mechanism are arranged behind the contact projections 23-25 of the second slider mechanism by rotating the knob 30 in clock wise direction to move the first slider mechanism along the second slider mechanism. Then the second slider mechanism is under active condition and the first slider mechanism is under non active condition. The contact projections 23-25 of the second slider mechanism are made to contact the second bimetal 60 so that the second bimetal 60 is deflected to contact the trip plate in the circuit breaker device. The second slider is moved to adjust the effective distance between the contact projections 23-25 and the second bimetal 60 to adjust the overload setting in the high range over load conditions.

[67] With respect to FIG .7, the second slider is in active state and the first slider which was in-active stage automatically gets deactivated. Now the second bimetal 60 goes to active state and hits the second slider, when the MCCB becomes overloaded. When the actuation knob 30 is rotated in the opposite direction the compression spring brings back the sliders to the original position. In all the above cases the linear displacement of the slider is dependent on the rotary motion of the knob 30.

[68] FIG. 8 shows a top side perspective view of the wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release in circuit breaker devices, according to one embodiment of the present invention, with the compression spring and the first and the second slider mechanisms in original position. With respect to FIG.8, a compression spring 70 is connected to the second slider mechanism and to a cover plate in the circuit breaker housing to bring back the sliders to the original position. The compression spring 70 is compressed and charged during the clock wise rotation of the actuating knob. The actuating knob 30 is rotated in anti clockwise direction to release the compression spring 70 to move the first slider mechanism and the second slider mechanism to the original position using the stored energy in the compression spring 70.

[69] FIG. 9 shows a top side perspective view of the three pole molded case circuit breaker with wide range overload adjustment mechanism with multiple bimetals for thermo-magnetic release according to one embodiment of the present invention. The circuit breaker has three poles. A slider assembly comprising a first slider mechanism and a second slider mechanism are provided in common to all the three poles of the circuit breaker. An actuating knob 30 is provided in common to adjust the overload setting. An actuating knob 90 for adjusting the short circuit condition is also provided in common to all the three poles. Each pole has a heater and a pair of bimetals.

[70] The thermo-magnetic release module with overload setting unit is enclosed in the housing 80 of the circuit breaker. The overload setting unit is designed for three pole operation, It is possible to design an overload setting unit for a single pole operation in a circuit breaker. The overload setting unit for three pole circuit breaker comprises of three heaters 40 and six bimetals so that each pole has one heater and two bimetals. The assembly also consists of a pair of adjustment knobs 30, 90 one for adjusting overload settings and the other for short-circuit settings. This present invention mainly deals with the overload adjustment which mainly consists of bimetals and the slider pair used for adjusting the effective gap between the bimetal and the slider.

G) ADVANTAGES OF THE INVENTION

[71] The various embodiments of the present invention provide a wide range overload setting unit with multiple bimetals for thermo-magnetic release in molded case circuit breaker. It comprises of a pair of bimetal, heater, pair of slider and an actuating knob for adjusting the effective gap between the bimetal and the slider to trip the molded case circuit breaker. The linear displacement of the sliders is used to increase or decrease the deflection of the bimetal to trip the circuit breaker depending on the direction of the motion of actuation knob. The overload setting unit is also used as a safety device for over current sensing. The thermal assembly in thermo- magnetic release for molded case circuit breaker is such that it can be manufactured for two releases one with extended current range and the other with lower current range . The overload setting unit can be used for single pole as well as 3 pole circuit breakers. The assembling of the various parts in the overload setting unit is very simple and hence can be manufactured with less effort.

[72] 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.

[73] 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 language might be said to fall there between.

CLAIMS

What is claimed is:

1. A wide range over load adjustment mechanism with multiple bimetals for thermo magnetic release in circuit breaker comprising:

A first slider mechanism;

A second slider mechanism coupled to the first slider mechanism;

An actuating knob connected to both the first slider mechanism and the
second slider mechanism;

A heater provided in the circuit breaker;

A trip plate provided in the circuit breaker;

A first bimetal connected to the heater and to the trip plate; and

A second bimetal connected to the heater and to the trip plate;

Wherein the actuating knob is rotated to adjust the effective distance between
the first slider mechanism and the first bimetal to activate the first slider
mechanism in low range over load conditions for adjusting the over load
setting in low ranges and to adjust the effective distance between the second
slider mechanism and the second bimetal to activate the second slider
mechanism and to deactivate the first slider mechanism in high range over
load conditions for adjusting the over load setting in high ranges.

2. The mechanism according to claim 1, wherein the actuating knob is rotated in clock wise direction to activate the first slider mechanism to deflect the first bimetal to activate the trip plate during the low range overload conditions while the actuating knob is rotated further in clock wise direction to activate the second slider mechanism to deflect the second bimetal to activate the trip plate and to deactivate the first slider mechanism during the high range overload conditions.

3. The mechanism according to claim 1, wherein the second slider mechanism is a main slider mechanism.

4. The mechanism wherein the first slider mechanism is an auxiliary slider mechanism.

5. The mechanism according to claim 1, wherein the first bimetal is a high sensitivity bimetal.

6. The mechanism according to claim 1, wherein the second bimetal is a low sensitivity bimetal.

7. The mechanism according to claim 1, wherein the first bimetal and the second bimetal have mutually different specific deflection, thermal conductivity and linearity range.

8. The mechanism according to claim 1, wherein the first bimetal is active during low range over voltage conditions.

9. The mechanism according to claim 1, wherein the second bimetal is active during high range over voltage conditions.

10. The mechanism according to claim 1, wherein the' actuating knob is an adjustment knob for overload setting.

11. The mechanism according to claim 1, wherein the actuating knob is rotated in clock wise direction to move the first slider mechanism linearly over the second slider mechanism to activate the first slider mechanism to adjust the effective distance between the first bimetal and the first slider mechanism to adjust the overload setting in low range so that the deflection of the first bimetal is used to activate the trip plate in low range overload conditions.

12. The mechanism according to claim 1, wherein the actuating knob is rotated further in clock wise direction to make the second slider mechanism move linearly along with the first slider mechanism to activate the second slider mechanism and to deactivate the first slider mechanism to adjust the effective distance between the second bimetal and the second slider mechanism to adjust the overload setting in high range so that the deflection of the second bimetal is used to activate the trip plate in high range overload conditions.

13. The mechanism according to claim 1, wherein each pole has a set of first bimetal and a second bimetal.

14. The mechanism according to claim 1, wherein each pole has a heater connected to both the first bimetal and a second bimetal.

15. The mechanism according to claim 1, wherein the first slider mechanism and the second slider mechanism are provided in common to all the poles in a circuit breaker.

16. The mechanism according to claim 1, further comprises a compression spring connected to the second slider mechanism and to a cover plate in the circuit breaker housing to bring backs the sliders to the original position.

17. The mechanism according to claim 16, wherein the compression springs are compressed and charged during the clock wise rotation of the actuating knob.

18. The mechanism according to claim 1, wherein the actuating knob is rotated in anti clockwise direction to release the compression spring to move the first slider mechanism and the second slider mechanism to the original position using the stored energy in the compression spring.