Title of Invention	QUAD BREAK MECHANISM FOR SWITCHING DEVICE
Abstract	The embodiments of the present invention provide a compact quad break mechanism for switching devices. The contact mechanism has a rotary contact which is coupled to a connecting link through a pivot. The connecting link is coupled to a knob through U-pin and to an operating lever which is lockably engaged to a locking lever. The operating lever is also connected to the knob through U-pin. The knob is moved to displace the connecting link to move the rotary contact to make and break electrical contacts at four locations to divide an arc into a series of low intensities to quench the arc quickly. The mechanism is also used to obtain 2 normally closed and 2 normally open contacts simultaneously.

Title of Invention

QUAD BREAK MECHANISM FOR SWITCHING DEVICE

Abstract

The embodiments of the present invention provide a compact quad break mechanism for switching devices. The contact mechanism has a rotary contact which is coupled to a connecting link through a pivot. The connecting link is coupled to a knob through U-pin and to an operating lever which is lockably engaged to a locking lever. The operating lever is also connected to the knob through U-pin. The knob is moved to displace the connecting link to move the rotary contact to make and break electrical contacts at four locations to divide an arc into a series of low intensities to quench the arc quickly. The mechanism is also used to obtain 2 normally closed and 2 normally open contacts simultaneously.

Full Text	FORM 2 THE PATENTS ACT, 1970 COMPLETE SPECIFICATION (See Section 10) QUAD BREAK MECHANISM FOR SWITCHING DEVICE Numbered as dated INVENTORS: a) VIRENDER SINGH BURA b) SATBIR SINGH c) CHANDRAKANT ANKUSH PATIL APPLICANT: M/s. LARSEN & TOUBRO LIMITED L&T House, Ballard Estate, P.O. Box No 278, Mumbai, 400 001, Maharashtra, INDIA THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THE INVENTION QUAD BREAK MECHANISM FOR SWITCHING DEVICE A) TECHNICAL FIELD [0001] The present invention generally relates to electrical power supply units and controllers used for domestic and industrial applications and particularly to switching devices such as Miniature Circuit Breaker, Residual Current Circuit Breaker, and isolator, etc., that are generally used to provide protection against over current, under current supply and or line leakages to the end product. The present invention more specifically relates to an electrical contact breaking mechanism or an arc quenching device used in switching devices like circuit breaker etc. B) BACKGROUND OF THE INVENTION [0002] The Electrical switching devices are used to protect the electrical circuitry and equipment from the damage due to an abnormal condition, such as an overload condition, a relatively high level short circuit or a fault condition. [0003] The electrical switching devices typically have two operating handle positions corresponding to the status of the separable contacts. For example, these positions include an ON position, in which the separable contacts are closed and an OFF position in which the contacts are open. Some switching "devices have a third position which corresponds to a tripped condition in which the contacts are tripped open. [0004] Switching devices are usually installed in an enclosure so that the entire control and distribution network arranged in the form of metallic sheets and/or cable wires are housed inside the enclosure. All the operating means are arranged outside the enclosure to prevent an access to the high voltage sections to eliminate the generation of a potential hazard. It is often desirable or essential that the settings of the switching devices remain undisturbed in the switching device during a maintenance operation. Unauthorized or inadvertent changing of the position of these breakers could result in unwanted interruptions to service or operations and serious damage to an electrical apparatus, or even serious harm to a person. For example, accidental actuation of a circuit breaker might result in electrocution or shock to a workman performing electrical work or repair on equipment downstream from the circuit breaker. [0005] Therefore enough safety measures must be taken to prevent another person from inadvertently returning the circuit breaker handle to the ON position, when a worker is doing electrical work in an area other than the immediate vicinity of the circuit breaker box or electrical panel. One such safety measure is the addition of a locking assembly to the switching device to prevent the displacement of the circuit breaker operating handle. [0006] A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city. There are multiple types of circuit breakers currently available in the market. For example, the different types of circuit breakers available in the market are the magnetic circuit breaker, the thermal breaker, the thermo magnetic circuit breaker etc. [0007] The Magnetic circuit breakers are provided with a solenoid (electromagnet) in which the pulling force is increased proportionately with the magnitude of current. The contacts in the circuit breaker are held closed by a latch. When the current passed through the solenoid increases beyond the preset rating of the circuit breaker, the latch is released by the pulling force of the solenoid to permit the contacts to be opened by a spring action. Some types of magnetic breakers have a hydraulic time delay feature to allow brief surge current beyond a preset level for starting motor or energizing electrical equipment. [0008] The Thermal breakers use a bimetallic strip, which is heated and bent with increased current, and is similarly arranged to release the latch. Such thermal breakers are commonly used with motor control circuits. Thermal breakers often have a compensation element to reduce the effect of ambient temperature on the device rating. [0009] The Thermo magnetic circuit breakers are "found mosdy in distribution boards. The thermo magnetic circuit breakers include both an electromagnet that responds instantaneously to large surges in current (short circuits) and the bimetallic strip which responds with respect to less extreme but long -term over current conditions. [0010] There are different technologies used in circuit breakers and they do not always fall into distinct categories. The commonly used circuit breakers in domestic, commercial and light industrial applications at low voltages (less than 1000 V) include a miniature circuit breaker (MCB) and a moulded case circuit breaker (MCCB). [0011] A miniature circuit breaker (MCB) is used for a rated current of not more than 100 A. the trip characteristics are not adjustable normally. The MCB employs thermal or thermo-magnetic principles. The MCCB (Moulded Case Circuit Breaker) is used for a rated current up to 1000 A. the MCCB uses the Thermal or thermal-magnetic operation. The trip current may be adjusted in MCCB. [0012] The Circuit breakers for larger currents are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism. [0013] The US Patent No. 6232570 discloses a rotary double-break circuit breaker which includes a case defining a circuit breaker enclosure with a rotatable bridge and contact arm arrangement. The contact arm has movable contacts, which is rotatable between a closed position and an open position. A pair of stationary contacts co-operates with the movable contacts, and a conductor is operatively connected to each of the stationary contacts for current input. [0014] The US Patent No.5030804 discloses a contact arrangement, particularly intended for current-limiting low voltage circuit breakers. The contact arrangement has a double break movable contact arm with the central portion attached to an insulating shaft which is rotatably moved in elongated holes in stand parts on each side of the contact arm. In the closed position of the arrangement, the movable contact arm is pressed against two U-shaped fixed contact arms with the aid of two torsion springs. [0015] The US patent No. 4910485 discloses a multiple circuit breaker with double break rotary contact arrangement. The circuit breaker has a pole provided with a pair of stationary contacts, a double break rotary contact and a switching bar provided with an arc chute at each end. Two contact pressure springs are provided to position the rotary contact along the longitudinal direction of the pole resiliently. r [0016] Under short-circuit conditions, a current which is several times greater than a normal level may flow through an electrical device. When the electrical contacts open to interrupt a large current, there is a tendency for an arc to form between the opened contacts, which would allow the flow of current to continue. Therefore, the circuit breakers must include various features to divide and extinguish the arc. In air-insulated and miniature breakers, an arc chute structure generally consisting of metal plates or ceramic ridges cools the arc, and blowout coils deflect the arc into the arc chute. Larger circuit breakers such as the one used in electrical, power distribution systems may use vacuum, an inert gas such as sulfur hexafluoride or have contacts immersed in oil to suppress the arc. [0017] In any kind of circuit breaker or switching device the arc plays a main role. If an arc may be extinguished in a better way, it improves the performance of the switching device. The two important methods used for extinguishing arc in a better way are, the lengthening of arc or the breaking of arc into various series arcs of low current intensity levels. These arcs of lower current intensities are easier to extinguish than to arc of greater current intensity. [0018] Auxiliary contact for low voltage switching devices now a days comes with either, two normally closed (NC) and one normally open (NO) contacts, or one normally closed (NC) and two normally open (NO) contacts i.e. (either 2 NO -1 NC or I NO - 2NC). [0019] None of the currently available circuit breakers have a compact contact arrangement of the quad-break type system particularly intended for low voltage switching devices to break the arc into a series of low intensity arcs to quench the arc effectively and efficiently. Also there is a need to obtain two normally open (NO) and two normally closed (NC) contacts simultaneously. C) OBJECT OF THE INVENTION [0020] The primary object of the present invention is to provide a switching device or circuit breaker with a quad break type compact contact arrangement to make and break contacts at multiple locations to quench an arc easily. [0021] Another object of the present invention is to provide a switching device with a rotary contact to divide an arc into a series of low intensity arcs to quench the arc generated between the contacts easily, efficiently and quickly. [0022] Yet another object of the present invention is to provide a switching device with an auxiliary contact having two normally closed and two normally open contacts simultaneously. D) SUMMARY OF THE PRESENT INVENTION [0023] The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification. [0024] According to one embodiment of the present invention, a switching device is provided with a quad break type compact contact to make and break contact at multiple places to divide an arc into a series of low intensity arcs so that each arc is extinguished easily and efficiendy. [0025] According to another embodiment of the present invention, a switching device is provided with a rotary contact to make and break electrical contact at four locations so that an arc is divided into a series of low intensity arcs to extinguish an arc easily and efficiendy. [0026] According to another embodiment of the present invention, a switching device is provided with an auxiliary contact to obtain two normally open (NO) and two normally closed contacts simultaneously. [0027] According to one embodiment of the present invention, the switching device is provided with a contact mechanism having a rotary contact. The rotary contact has four arms to make and break contacts with fixed or stationary contacts at four locations. The rotary contact is connected to a connecting link through a pivot. The other end of the connecting link is coupled to an operating knob through a U-pin. The operating knob is also connected to an operating lever through the U-pin. The other end of the operating lever is lockingly engaged with a locking lever. When the operating knob is moved, the connecting link is also moved to displace the rotary contact to make and break contact at four places. The contact opens at four different locations giving rise to four arcs of lower current intensities so that the four arcs of low intensity levels may be extinguished easily to improve the breaking capacity of the circuit breaker. [0028] According to another embodiment of the present invention, the compact contact mechanism is used for auxiliary contacts in a circuit breaker. When the circuit breaker is switched ON, the rotary contact makes contact with the fixed contacts at four locations and when switched OFF, it breaks contacts with fixed contacts. When the assembly is used in auxiliary contact, then during ON condition the rotary contact makes contact with the fixed contacts at four locations to provide two closed contacts and two open contacts (2 NC and 2 NO). When the circuit breaker is switched OFF, the rotary contact breaks contacts with fixed contact to make contact with other contacts which were open earlier thereby converting NC to NO and NO to NC. [0029] Thus the various embodiments of the present invention provides a switching device with a quad break type compact contact mechanism to make and break contacts at several locations to divide an arc into a series of low intensity arcs so that the arc is extinguished easily and efficiendy. The compact contact mechanism is used in an auxiliary contact mechanism to obtain 2 NC and 2 NO contacts simultaneously. [0030] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. E) BRIEF DESCRIPTION OF THE DRAWINGS [0031] 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: [0032] FIG. 1 illustrates a side sectional view of a switching device with a compact contact switching mechanism according to one embodiment of the present invention, with the switch in ON position to make contacts at four locations. [0033] FIG. 2 illustrates a side sectional view of a switching device with a compact contact switching mechanism according to one embodiment of the present invention, with the switch in OFF position to break four contacts. [0034] FIG. 3 illustrates a side sectional view of a switching device with a compact contact switching mechanism according to one embodiment of the present invention, with the switch in ON position to make moving contact arms to establish contacts at four locations with fixed contacts. [0035] FIG. 4 illustrates a side sectional view of a switching device with a compact contact switching mechanism according to one embodiment of the present invention, with the switch in OFF position to make moving contact arms to break the four contacts. [0036] 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 PRESENT INVENTION [0037] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments which 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. [0038] According to one embodiment of the present invention, the switching device is provided with a contact mechanism having a rotary contact. The rotary contact has four arms to make and break contacts with fixed or stationary contacts at four locations. The rotary contact is connected to a connecting link through a pivot. The other end of the connecting link is coupled to an operating knob through a U-pin. The operating knob is also connected to an operating lever through the U-pin. The other end of the operating lever is lockingly engaged with a locking lever. When the operating knob is moved, the connecting link is also moved to displace the rotary contact to make and break contact at four places. The contact opens at four different locations giving rise to four arcs of lower current intensities so that the four arcs of low intensity levels may be extinguished easily to improve the breaking capacity of the circuit breaker. [0039] According to another embodiment of the present invention, the compact contact mechanism is used for auxiliary contacts in a circuit breaker. When the circuit breaker is switched ON, the rotary contact makes contact with the fixed contacts at four locations. When switched OFF, the rotary contact is moved to break contacts with fixed contacts. When the compact contact assembly is used for auxiliary contact, then the rotary contact makes contact with the fixed contacts at four locations during the switched ON condition of the circuit breaker to provide two closed contacts and two open contacts (2 NC and 2 NO). When the circuit breaker is switched OFF, the rotary contact is moved to break contact with existing fixed contacts to make contact with other contacts which were open earlier, thereby converting NC to NO and NO to NC. [0040] Thus the various embodiments of the present invention provides a switching device with a quad break type compact contact mechanism to make and break contacts at several locations to divide an arc into a series of low intensity arcs so that the arc is extinguished easily and efficiendy. The compact contact mechanism is used in an auxiliary contact mechanism to obtain 2 NC and 2 NO contacts simultaneously. [0041] The FIG. 1 and FIG. 2 indicate a side sectional view of a switching device provided with a compact contact mechanism according to one embodiment of the present invention, with the switch in ON and OFF conditions respectively. [0042] With respect to the FIG. 1 and FIG. 2, the switching device has a rotary contact 1 provided with several movable arms to make and break electrical contact with fixed contacts 8. An operating knob 2 is connected to a U-Pin 6. The U-Pin 6 is then connected to an operating lever 5 and to a connecting link 4. One end of the connecting link 4 is coupled to the knob 2 through the U-pin 6, while the other end of the connecting link 4 is attached to a rotary contact 1 through a pivot 3. The movement of the connecting link 4 is transferred to the rotary contact 1 with the help of a pivot 3 so that the connecting link 4 is moved by operating the knob 2 to rotate the rotary contact 1 to make and break the fixed contacts 8. One end of the operating lever 5 is coupled to the knob 2 through the U-pin 6, while the other end of the operating lever 5 is lockingly engaged to a locking lever 7. When the circuit breaker is switched on (FIG. 2), the U Pin 6 connected to knob 2 is pushed up to move the connecting link 4 accordingly. Then the movement of the connecting link is transferred to the rotary contact 1. But since the operating lever 5 is locked from other side by the locking lever 7 the connecting link 4 will move down and will push the pivot 8 through which it is connected to rotary contact 1. [0043] The contact assembly mechanism may also be used for auxiliary contacts in a switching device. The operation of the mechanism used in auxiliary contact may be easily illustrated again with respect to the FIG. 1 and FIG. 2. When the mechanism is used in circuit breaker, the rotary contact 1 during switched ON condition, makes contact with the fixed contacts 8 at four locations as shown in FIG. 1. When the circuit breaker is switched OFF, the rotary contact is moved away from the existing contacts to break contacts with fixed contact 8 as shown in FIG. 2. But when the contact assembly is used in the auxiliary contact, the rotary contact 1, during switched ON condition, makes contact with the fixed contacts 8 at four locations to provide two closed contacts and two open contacts (2 NC and 2 NO) as shown in FIG. 1. But when the circuit breaker is switched OFF, the rotary contact is moved to break contacts with existing fixed contact (8) and to make contact with other fixed contacts which are open earlier, to convert NC to NO and NO to NC. [0043] The FIG. 3 and FIG. 4 indicate a side sectional view of a switching device with a compact contact switching mechanism according to one embodiment of the present invention, with the switch in ON and OFF positions to make moving contact arms to make and break contacts at four locations with fixed contacts. [0044] With respect to FIG. 3 and 4, the switching device has an operating knob 2 which is connected to a U-Pin 6. The U-Pin 6 is then connected to an operating lever 5 and to a connecting link 4. One end of the connecting link 4 is coupled to the knob 2 through the U-pin 6, while the other end of the connecting link 4 is attached to a rotary contact 1 through a pivot 3. The movement of the connecting link 4 is transferred to the rotary contact 1 with the help of a pivot 3 so that the connecting link 4 is moved by operating the knob 2 to rotate the rotary contact 1 to make and break the fixed contacts 8. One end of the operating lever 5 is coupled to the knob 2 through the U-pin 6, while the other end of the operating lever 5 is lockingly engaged to a locking lever 7. The rotary contact has four moving contact arms la-Id for making and breaking contacts with fixed contacts 8a- 8d at four locations. G) ADVANTAGES OF THE INVENTION [0045] The various embodiments of the present invention provide a switching device with a compact contact mechanism to make and break contact at multiple locations to divide an arc into a series of low intensity arcs to extinguish the arc efficiendy, easily and quickly thereby improving the breaking capacity. The compact contact assembly may be used for an auxiliary contact in the circuit breaker or switching device. The rotary contact used in the contact mechanism has a unique design and compact structure. The rotary contact makes and brakes contact at four locations to improve the breaking capacity of the circuit breaker. The rotary contact breaks from the fixed contact at four locations to break an arc into four arcs of low intensities to quench an arc easily and efficiendy. Since the arc is broken at four places, the energy passed through the circuit breaker is reduced. As the arc is broken into multiple arcs, the arc is quenched quickly. The contact mechanism is used for an auxiliary contact to obtain 2 NO -2 NC contacts simultaneously. The contact mechanism may be used in any kind of low voltage breaker for making and breaking electrical contacts. [0046] It is also to be understood that the following claims are intended to cover all of die 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 quad break mechanism for switching device comprising; an operating knob; an operating lever connected to said operating knob; a locking lever engaged to said operating lever; a connecting link operably coupled to said operating knob; and a rotary contact coupled to said connecting link; wherein said operating knob is moved to displace said connecting link to move said rotary contact to make or break electrical contacts to divide an arc into a series of arc of lower intensities to quench said arc completely. 2. The mechanism according to claim 1, wherein the rotary contact has plurality of movable arms to make and break electrical contacts at multiple locations. 3. The mechanism according to claim 2, wherein the rotary contact has 4 movable arms to make and break electrical contacts. 4. The mechanism according to claim 1, further comprises plurality of stationary contacts. 5. The mechanism according to claim 1, wherein the rotary contact is moved to make and break electrical contacts with said stationary contacts. 6. The mechanism according to claim 1, wherein said operating lever is connected to said operating knob through a pin. 7. The mechanism according to claim 6, wherein said pin is a U-shaped pin. 8. The mechanism according to claim 1, wherein said connecting link is coupled to said operating knob through a pin. 9. The mechanism according to claim 8, wherein said pin is a U-shaped pin. 10. The mechanism according to claim 1, wherein said operating lever and said connecting link are coupled to said operating knob through a same pin. 11. The mechanism according to claim 10, wherein the pin is a u-shaped pin. 12. The mechanism according to claiml, wherein said connecting link is coupled to said rotary contact through a pivot. 13. The mechanism according to claim 1, wherein said operating knob is moved between ON and OFF positions. 14. The mechanism according to claim 1, wherein said locking lever locks or releases the operating lever. 15. A quad break type contact mechanism for auxiliary contact in switching device, comprising: an operating knob; an operating lever connected to said operating knob; a locking lever engaged to said operating lever; a connecting link operably coupled to said operating knob; and a rotary contact coupled to said connecting link; wherein said operating knob is moved to displace said connecting link to move said rotary contact to make or break electrical contacts so that a preset number of normally closed and normally open contacts are obtained. 16. The mechanism according to claim 15, wherein the rotary contact has plurahty of movable arms to make and break electrical contacts at multiple locations. 17. The mechanism according to claim 16, wherein the rotary contact has 4 movable arms to make and break electrical contacts. 18. The mechanism according to claim 15, further comprises plurality of stationary contacts. 19. The mechanism according to claim 18, the number of stationary contacts is equal to 4. 20. The mechanism according to claim 15, wherein the rotary contact is moved to make electrical contact with a predetermined number of stationary contacts to close contacts and to move away from predetermined number of stationary contacts to break contacts at a given point pf time to obtain an equal number of normally open (NO) contacts and normally closed (NC) contacts simultaneously at given point of time. 21. The mechanism according to claim 20, the rotary contact is moved subsequently to make the NO contacts into NC contacts and vice versa. 22. The mechanism according to claim 20, the rotary contact is moved to make 2 NO contacts and 2 NC contacts simultaneously at any given point of time. 23. The mechanism according to claim 15, wherein said operating lever is connected to said operating knob through a pin. 24. The mechanism according to claim 23, wherein said pin is a U-shaped pin. 25. The mechanism according to claim 15, wherein said connecting link is coupled to said operating knob through a pin. 26. The mechanism according to claim 25, wherein said pin is a U-shaped pin. 27. The mechanism according to claim 15, wherein said operating lever and said connecting link are coupled to said operating knob through a same pin. 28. The mechanism according to claim 27, wherein the pin is a u-shaped pin. 29. The mechanism according to claiml5, wherein said connecting link is coupled to said rotary contact through a pivot. 30. The mechanism according to claim 15, wherein said operating knob is moved between ON and OFF positions. 31. The mechanism according to claim 15, wherein said locking lever locks or releases the operating lever. Rakesh Prabhu, Patent Agent, ALMT Legal, No.2, Lavelle Road, Bangalore-560 001, INDIA To, The Controller of Patents, The Patent office, At Mumbai ABSTRACT The embodiments of the present invention provide a compact quad break mechanism for switching devices. The contact mechanism has a rotary contact which is coupled to a connecting link through a pivot. The connecting link is coupled to a knob through U -pin and to an operating lever which is lockably engaged to a locking lever. The operating lever is also connected to the knob through U-pin. The knob is moved to displace the connecting link to move the rotary contact to make and break electrical contacts at four locations to divide an arc into a series of arc of low intensities to quench the arc quickly. The mechanism is also used to obtain 2 normally closed and 2 normally open contacts simultaneously. 31 Claims, 4 Drawing Sheets.

Full Text

FORM 2
THE PATENTS ACT, 1970 COMPLETE SPECIFICATION
(See Section 10)
QUAD BREAK MECHANISM FOR SWITCHING DEVICE
Numbered as dated
INVENTORS:
a) VIRENDER SINGH BURA
b) SATBIR SINGH
c) CHANDRAKANT ANKUSH PATIL
APPLICANT:
M/s. LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No 278, Mumbai, 400 001, Maharashtra,
INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
NATURE OF THE INVENTION

QUAD BREAK MECHANISM FOR SWITCHING DEVICE
A) TECHNICAL FIELD
[0001] The present invention generally relates to electrical power supply units and controllers used for domestic and industrial applications and particularly to switching devices such as Miniature Circuit Breaker, Residual Current Circuit Breaker, and isolator, etc., that are generally used to provide protection against over current, under current supply and or line leakages to the end product. The present invention more specifically relates to an electrical contact breaking mechanism or an arc quenching device used in switching devices like circuit breaker etc.
B) BACKGROUND OF THE INVENTION
[0002] The Electrical switching devices are used to protect the electrical circuitry and equipment from the damage due to an abnormal condition, such as an overload condition, a relatively high level short circuit or a fault condition.
[0003] The electrical switching devices typically have two operating handle positions corresponding to the status of the separable contacts. For example, these positions include an ON position, in which the separable contacts are closed and an OFF position in which the contacts are open. Some switching "devices have a third position which corresponds to a tripped condition in which the contacts are tripped open.

[0004] Switching devices are usually installed in an enclosure so that the entire control and distribution network arranged in the form of metallic sheets and/or cable wires are housed inside the enclosure. All the operating means are arranged outside the enclosure to prevent an access to the high voltage sections to eliminate the generation of a potential hazard. It is often desirable or essential that the settings of the switching devices remain undisturbed in the switching device during a maintenance operation. Unauthorized or inadvertent changing of the position of these breakers could result in unwanted interruptions to service or operations and serious damage to an electrical apparatus, or even serious harm to a person. For example, accidental actuation of a circuit breaker might result in electrocution or shock to a workman performing electrical work or repair on equipment downstream from the circuit breaker.
[0005] Therefore enough safety measures must be taken to prevent another person from inadvertently returning the circuit breaker handle to the ON position, when a worker is doing electrical work in an area other than the immediate vicinity of the circuit breaker box or electrical panel. One such safety measure is the addition of a locking assembly to the switching device to prevent the displacement of the circuit breaker operating handle.
[0006] A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city. There are multiple types of circuit breakers currently available in the market. For example, the different types of

circuit breakers available in the market are the magnetic circuit breaker, the thermal breaker, the thermo magnetic circuit breaker etc.
[0007] The Magnetic circuit breakers are provided with a solenoid (electromagnet) in which the pulling force is increased proportionately with the magnitude of current. The contacts in the circuit breaker are held closed by a latch. When the current passed through the solenoid increases beyond the preset rating of the circuit breaker, the latch is released by the pulling force of the solenoid to permit the contacts to be opened by a spring action. Some types of magnetic breakers have a hydraulic time delay feature to allow brief surge current beyond a preset level for starting motor or energizing electrical equipment.
[0008] The Thermal breakers use a bimetallic strip, which is heated and bent with increased current, and is similarly arranged to release the latch. Such thermal breakers are commonly used with motor control circuits. Thermal breakers often have a compensation element to reduce the effect of ambient temperature on the device rating.
[0009] The Thermo magnetic circuit breakers are "found mosdy in distribution boards. The thermo magnetic circuit breakers include both an electromagnet that responds instantaneously to large surges in current (short circuits) and the bimetallic strip which responds with respect to less extreme but long -term over current conditions.
[0010] There are different technologies used in circuit breakers and they do not always fall into distinct categories. The commonly used circuit breakers in domestic, commercial and light industrial applications at low voltages (less than 1000 V) include a miniature circuit breaker (MCB) and a moulded case circuit breaker (MCCB).

[0011] A miniature circuit breaker (MCB) is used for a rated current of not more than 100 A. the trip characteristics are not adjustable normally. The MCB employs thermal or thermo-magnetic principles. The MCCB (Moulded Case Circuit Breaker) is used for a rated current up to 1000 A. the MCCB uses the Thermal or thermal-magnetic operation. The trip current may be adjusted in MCCB.
[0012] The Circuit breakers for larger currents are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism.
[0013] The US Patent No. 6232570 discloses a rotary double-break circuit breaker which includes a case defining a circuit breaker enclosure with a rotatable bridge and contact arm arrangement. The contact arm has movable contacts, which is rotatable between a closed position and an open position. A pair of stationary contacts co-operates with the movable contacts, and a conductor is operatively connected to each of the stationary contacts for current input.
[0014] The US Patent No.5030804 discloses a contact arrangement, particularly intended for current-limiting low voltage circuit breakers. The contact arrangement has a double break movable contact arm with the central portion attached to an insulating shaft which is rotatably moved in elongated holes in stand parts on each side of the contact arm. In the closed position of the arrangement, the movable contact arm is pressed against two U-shaped fixed contact arms with the aid of two torsion springs.
[0015] The US patent No. 4910485 discloses a multiple circuit breaker with double break rotary contact arrangement. The circuit breaker has a pole provided with a pair of stationary contacts, a double break rotary contact and a switching bar provided with an

arc chute at each end. Two contact pressure springs are provided to position the rotary contact along the longitudinal direction of the pole resiliently.
r
[0016] Under short-circuit conditions, a current which is several times greater than a normal level may flow through an electrical device. When the electrical contacts open to interrupt a large current, there is a tendency for an arc to form between the opened contacts, which would allow the flow of current to continue. Therefore, the circuit breakers must include various features to divide and extinguish the arc. In air-insulated and miniature breakers, an arc chute structure generally consisting of metal plates or ceramic ridges cools the arc, and blowout coils deflect the arc into the arc chute. Larger circuit breakers such as the one used in electrical, power distribution systems may use vacuum, an inert gas such as sulfur hexafluoride or have contacts immersed in oil to suppress the arc.
[0017] In any kind of circuit breaker or switching device the arc plays a main role. If an arc may be extinguished in a better way, it improves the performance of the switching device. The two important methods used for extinguishing arc in a better way are, the lengthening of arc or the breaking of arc into various series arcs of low current intensity levels. These arcs of lower current intensities are easier to extinguish than to arc of greater current intensity.
[0018] Auxiliary contact for low voltage switching devices now a days comes with either, two normally closed (NC) and one normally open (NO) contacts, or one normally closed (NC) and two normally open (NO) contacts i.e. (either 2 NO -1 NC or I NO - 2NC).
[0019] None of the currently available circuit breakers have a compact contact arrangement of the quad-break type system particularly intended for low voltage

switching devices to break the arc into a series of low intensity arcs to quench the arc effectively and efficiently. Also there is a need to obtain two normally open (NO) and two normally closed (NC) contacts simultaneously.
C) OBJECT OF THE INVENTION
[0020] The primary object of the present invention is to provide a switching device or circuit breaker with a quad break type compact contact arrangement to make and break contacts at multiple locations to quench an arc easily.
[0021] Another object of the present invention is to provide a switching device with a rotary contact to divide an arc into a series of low intensity arcs to quench the arc generated between the contacts easily, efficiently and quickly.
[0022] Yet another object of the present invention is to provide a switching device with an auxiliary contact having two normally closed and two normally open contacts simultaneously.
D) SUMMARY OF THE PRESENT INVENTION
[0023] The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.

[0024] According to one embodiment of the present invention, a switching device is provided with a quad break type compact contact to make and break contact at multiple places to divide an arc into a series of low intensity arcs so that each arc is extinguished easily and efficiendy.
[0025] According to another embodiment of the present invention, a switching device is provided with a rotary contact to make and break electrical contact at four locations so that an arc is divided into a series of low intensity arcs to extinguish an arc easily and efficiendy.
[0026] According to another embodiment of the present invention, a switching device is provided with an auxiliary contact to obtain two normally open (NO) and two normally closed contacts simultaneously.
[0027] According to one embodiment of the present invention, the switching device is provided with a contact mechanism having a rotary contact. The rotary contact has four arms to make and break contacts with fixed or stationary contacts at four locations. The rotary contact is connected to a connecting link through a pivot. The other end of the connecting link is coupled to an operating knob through a U-pin. The operating knob is also connected to an operating lever through the U-pin. The other end of the operating lever is lockingly engaged with a locking lever. When the operating knob is moved, the connecting link is also moved to displace the rotary contact to make and break contact at four places. The contact opens at four different locations giving rise to four arcs of lower current intensities so that the four arcs of low intensity levels may be extinguished easily to improve the breaking capacity of the circuit breaker.

[0028] According to another embodiment of the present invention, the compact contact mechanism is used for auxiliary contacts in a circuit breaker. When the circuit breaker is switched ON, the rotary contact makes contact with the fixed contacts at four locations and when switched OFF, it breaks contacts with fixed contacts. When the assembly is used in auxiliary contact, then during ON condition the rotary contact makes contact with the fixed contacts at four locations to provide two closed contacts and two open contacts (2 NC and 2 NO). When the circuit breaker is switched OFF, the rotary contact breaks contacts with fixed contact to make contact with other contacts which were open earlier thereby converting NC to NO and NO to NC.
[0029] Thus the various embodiments of the present invention provides a switching device with a quad break type compact contact mechanism to make and break contacts at several locations to divide an arc into a series of low intensity arcs so that the arc is extinguished easily and efficiendy. The compact contact mechanism is used in an auxiliary contact mechanism to obtain 2 NC and 2 NO contacts simultaneously.
[0030] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0031] 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:

[0032] FIG. 1 illustrates a side sectional view of a switching device with a compact contact switching mechanism according to one embodiment of the present invention, with the switch in ON position to make contacts at four locations.
[0033] FIG. 2 illustrates a side sectional view of a switching device with a compact contact switching mechanism according to one embodiment of the present invention, with the switch in OFF position to break four contacts.
[0034] FIG. 3 illustrates a side sectional view of a switching device with a compact contact switching mechanism according to one embodiment of the present invention, with the switch in ON position to make moving contact arms to establish contacts at four locations with fixed contacts.
[0035] FIG. 4 illustrates a side sectional view of a switching device with a compact contact switching mechanism according to one embodiment of the present invention, with the switch in OFF position to make moving contact arms to break the four contacts.
[0036] 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 PRESENT INVENTION
[0037] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments which 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.
[0038] According to one embodiment of the present invention, the switching device is provided with a contact mechanism having a rotary contact. The rotary contact has four arms to make and break contacts with fixed or stationary contacts at four locations. The rotary contact is connected to a connecting link through a pivot. The other end of the connecting link is coupled to an operating knob through a U-pin. The operating knob is also connected to an operating lever through the U-pin. The other end of the operating lever is lockingly engaged with a locking lever. When the operating knob is moved, the connecting link is also moved to displace the rotary contact to make and break contact at four places. The contact opens at four different locations giving rise to four arcs of lower current intensities so that the four arcs of low intensity levels may be extinguished easily to improve the breaking capacity of the circuit breaker.
[0039] According to another embodiment of the present invention, the compact contact mechanism is used for auxiliary contacts in a circuit breaker. When the circuit breaker is switched ON, the rotary contact makes contact with the fixed contacts at four locations. When switched OFF, the rotary contact is moved to break contacts with fixed contacts. When the compact contact assembly is used for auxiliary contact, then the rotary contact makes contact with the fixed contacts at four locations during the switched ON condition of the circuit breaker to provide two closed contacts and two open contacts (2 NC and 2 NO). When the circuit breaker is switched OFF, the rotary contact is moved

to break contact with existing fixed contacts to make contact with other contacts which were open earlier, thereby converting NC to NO and NO to NC.
[0040] Thus the various embodiments of the present invention provides a switching device with a quad break type compact contact mechanism to make and break contacts at several locations to divide an arc into a series of low intensity arcs so that the arc is extinguished easily and efficiendy. The compact contact mechanism is used in an auxiliary contact mechanism to obtain 2 NC and 2 NO contacts simultaneously.
[0041] The FIG. 1 and FIG. 2 indicate a side sectional view of a switching device provided with a compact contact mechanism according to one embodiment of the present invention, with the switch in ON and OFF conditions respectively.
[0042] With respect to the FIG. 1 and FIG. 2, the switching device has a rotary contact 1 provided with several movable arms to make and break electrical contact with fixed contacts 8. An operating knob 2 is connected to a U-Pin 6. The U-Pin 6 is then connected to an operating lever 5 and to a connecting link 4. One end of the connecting link 4 is coupled to the knob 2 through the U-pin 6, while the other end of the connecting link 4 is attached to a rotary contact 1 through a pivot 3. The movement of the connecting link 4 is transferred to the rotary contact 1 with the help of a pivot 3 so that the connecting link 4 is moved by operating the knob 2 to rotate the rotary contact 1 to make and break the fixed contacts 8. One end of the operating lever 5 is coupled to the knob 2 through the U-pin 6, while the other end of the operating lever 5 is lockingly engaged to a locking lever 7. When the circuit breaker is switched on (FIG. 2), the U Pin 6 connected to knob 2 is pushed up to move the connecting link 4 accordingly. Then the movement of the connecting link is transferred to the rotary contact 1. But since the

operating lever 5 is locked from other side by the locking lever 7 the connecting link 4 will move down and will push the pivot 8 through which it is connected to rotary contact 1.
[0043] The contact assembly mechanism may also be used for auxiliary contacts in a switching device. The operation of the mechanism used in auxiliary contact may be easily illustrated again with respect to the FIG. 1 and FIG. 2. When the mechanism is used in circuit breaker, the rotary contact 1 during switched ON condition, makes contact with the fixed contacts 8 at four locations as shown in FIG. 1. When the circuit breaker is switched OFF, the rotary contact is moved away from the existing contacts to break contacts with fixed contact 8 as shown in FIG. 2. But when the contact assembly is used in the auxiliary contact, the rotary contact 1, during switched ON condition, makes contact with the fixed contacts 8 at four locations to provide two closed contacts and two open contacts (2 NC and 2 NO) as shown in FIG. 1. But when the circuit breaker is switched OFF, the rotary contact is moved to break contacts with existing fixed contact (8) and to make contact with other fixed contacts which are open earlier, to convert NC to NO and NO to NC.
[0043] The FIG. 3 and FIG. 4 indicate a side sectional view of a switching device with a compact contact switching mechanism according to one embodiment of the present invention, with the switch in ON and OFF positions to make moving contact arms to make and break contacts at four locations with fixed contacts.
[0044] With respect to FIG. 3 and 4, the switching device has an operating knob 2 which is connected to a U-Pin 6. The U-Pin 6 is then connected to an operating lever 5 and to a connecting link 4. One end of the connecting link 4 is coupled to the knob 2 through

the U-pin 6, while the other end of the connecting link 4 is attached to a rotary contact 1 through a pivot 3. The movement of the connecting link 4 is transferred to the rotary contact 1 with the help of a pivot 3 so that the connecting link 4 is moved by operating the knob 2 to rotate the rotary contact 1 to make and break the fixed contacts 8. One end of the operating lever 5 is coupled to the knob 2 through the U-pin 6, while the other end of the operating lever 5 is lockingly engaged to a locking lever 7. The rotary contact has four moving contact arms la-Id for making and breaking contacts with fixed contacts 8a- 8d at four locations.
G) ADVANTAGES OF THE INVENTION
[0045] The various embodiments of the present invention provide a switching device with a compact contact mechanism to make and break contact at multiple locations to divide an arc into a series of low intensity arcs to extinguish the arc efficiendy, easily and quickly thereby improving the breaking capacity. The compact contact assembly may be used for an auxiliary contact in the circuit breaker or switching device. The rotary contact used in the contact mechanism has a unique design and compact structure. The rotary contact makes and brakes contact at four locations to improve the breaking capacity of the circuit breaker. The rotary contact breaks from the fixed contact at four locations to break an arc into four arcs of low intensities to quench an arc easily and efficiendy. Since the arc is broken at four places, the energy passed through the circuit breaker is reduced. As the arc is broken into multiple arcs, the arc is quenched quickly. The contact mechanism is used for an auxiliary contact to obtain 2 NO -2 NC contacts simultaneously. The contact mechanism may be used in any kind of low voltage breaker for making and breaking electrical contacts.

[0046] It is also to be understood that the following claims are intended to cover all of die 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 quad break mechanism for switching device comprising;
an operating knob;
an operating lever connected to said operating knob;
a locking lever engaged to said operating lever;
a connecting link operably coupled to said operating knob; and
a rotary contact coupled to said connecting link;
wherein said operating knob is moved to displace said connecting link to move said rotary contact to make or break electrical contacts to divide an arc into a series of arc of lower intensities to quench said arc completely.
2. The mechanism according to claim 1, wherein the rotary contact has plurality of movable arms to make and break electrical contacts at multiple locations.
3. The mechanism according to claim 2, wherein the rotary contact has 4 movable arms to make and break electrical contacts.
4. The mechanism according to claim 1, further comprises plurality of stationary contacts.
5. The mechanism according to claim 1, wherein the rotary contact is moved to make and break electrical contacts with said stationary contacts.

6. The mechanism according to claim 1, wherein said operating lever is connected to said operating knob through a pin.
7. The mechanism according to claim 6, wherein said pin is a U-shaped pin.
8. The mechanism according to claim 1, wherein said connecting link is coupled to said operating knob through a pin.
9. The mechanism according to claim 8, wherein said pin is a U-shaped pin.
10. The mechanism according to claim 1, wherein said operating lever and said connecting link are coupled to said operating knob through a same pin.
11. The mechanism according to claim 10, wherein the pin is a u-shaped pin.
12. The mechanism according to claiml, wherein said connecting link is coupled to said rotary contact through a pivot.
13. The mechanism according to claim 1, wherein said operating knob is moved between ON and OFF positions.

14. The mechanism according to claim 1, wherein said locking lever locks or releases the operating lever.
15. A quad break type contact mechanism for auxiliary contact in switching device, comprising:

an operating knob; an operating lever connected to said operating knob; a locking lever engaged to said operating lever; a connecting link operably coupled to said operating knob; and a rotary contact coupled to said connecting link;
wherein said operating knob is moved to displace said connecting link to move said rotary contact to make or break electrical contacts so that a preset number of normally closed and normally open contacts are obtained.
16. The mechanism according to claim 15, wherein the rotary contact has plurahty of movable arms to make and break electrical contacts at multiple locations.
17. The mechanism according to claim 16, wherein the rotary contact has 4 movable arms to make and break electrical contacts.
18. The mechanism according to claim 15, further comprises plurality of stationary contacts.
19. The mechanism according to claim 18, the number of stationary contacts is equal to 4.
20. The mechanism according to claim 15, wherein the rotary contact is moved to
make electrical contact with a predetermined number of stationary contacts to
close contacts and to move away from predetermined number of stationary
contacts to break contacts at a given point pf time to obtain an equal number of

normally open (NO) contacts and normally closed (NC) contacts simultaneously at given point of time.
21. The mechanism according to claim 20, the rotary contact is moved subsequently
to make the NO contacts into NC contacts and vice versa.
22. The mechanism according to claim 20, the rotary contact is moved to make 2 NO contacts and 2 NC contacts simultaneously at any given point of time.
23. The mechanism according to claim 15, wherein said operating lever is connected to said operating knob through a pin.
24. The mechanism according to claim 23, wherein said pin is a U-shaped pin.
25. The mechanism according to claim 15, wherein said connecting link is coupled to said operating knob through a pin.
26. The mechanism according to claim 25, wherein said pin is a U-shaped pin.
27. The mechanism according to claim 15, wherein said operating lever and said connecting link are coupled to said operating knob through a same pin.
28. The mechanism according to claim 27, wherein the pin is a u-shaped pin.
29. The mechanism according to claiml5, wherein said connecting link is coupled to said rotary contact through a pivot.

30. The mechanism according to claim 15, wherein said operating knob is moved
between ON and OFF positions.
31. The mechanism according to claim 15, wherein said locking lever locks or
releases the operating lever.

Rakesh Prabhu,
Patent Agent, ALMT Legal,
No.2, Lavelle Road, Bangalore-560 001, INDIA
To,
The Controller of Patents,
The Patent office,
At Mumbai

ABSTRACT
The embodiments of the present invention provide a compact quad break mechanism for switching devices. The contact mechanism has a rotary contact which is coupled to a connecting link through a pivot. The connecting link is coupled to a knob through U -pin and to an operating lever which is lockably engaged to a locking lever. The operating lever is also connected to the knob through U-pin. The knob is moved to displace the connecting link to move the rotary contact to make and break electrical contacts at four locations to divide an arc into a series of arc of low intensities to quench the arc quickly. The mechanism is also used to obtain 2 normally closed and 2 normally open contacts simultaneously.
31 Claims, 4 Drawing Sheets.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=jiNZUSiRW2/EJsvcgt8Wpw==&loc=vsnutRQWHdTHa1EUofPtPQ==

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Patent Number

269811

Indian Patent Application Number

2591/MUM/2007

PG Journal Number

46/2015

Publication Date

13-Nov-2015

Grant Date

07-Nov-2015

Date of Filing

27-Dec-2007

Name of Patentee

LARSEN & TOUBRO LIMITED

Applicant Address

L&T HOUSE, BALLARD ESTATE, P.O.BOX NO. 278, MUMBAI.

Inventors:

#	Inventor's Name	Inventor's Address
1	VIRENDER SINGH BURA	SWITCHGEAR DESIGN & PRODUCT DEVELOPMENT CENTER, LARSEN & TOUBRO LIMITED, ELECTRICAL SECTOR-(EBG), POWAI WORKS(EAST), GATE NO. 7, SAKI VIHAR ROAD, MUMBAI-400072.
2	SATBIR SINGH	SWITCHGEAR DESIGN & PRODUCT DEVELOPMENT CENTER, LARSEN & TOUBRO LIMITED, ELECTRICAL SECTOR-(EBG), POWAI WORKS(EAST), GATE NO. 7, SAKI VIHAR ROAD, MUMBAI-400072.
3	CHANDRAKANT ANKUSH PATIL	SWITCHGEAR DESIGN & PRODUCT DEVELOPMENT CENTER, LARSEN & TOUBRO LIMITED, ELECTRICAL SECTOR-(EBG), POWAI WORKS(EAST), GATE NO. 7, SAKI VIHAR ROAD, MUMBAI-400072.

PCT International Classification Number

H01H 9/30

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA