Title of Invention	DOUBLE BREAK CONTACT ARRANGEMENT FOR MINIATURE CIRCUIT BREAKERS
Abstract	The present invention relates to a contact system for breaking current into plurality of arcs ensuring double arc length. The contact system comprises housing (6), plurality of contact members which comprises fixed and moving contact members (2, 3). The fixed and moving contact members (2, 3) are ergonomically designed to produce high electrodynamic forces. Guide means (4) is operatively connected to the moving contact member (3) by means of a rigid bar means (11) and to support a spring mechanism for compression and/or decompression in ON and/or OFF operation. Arc chutes (10) are placed beneath the fixed contact (2) in an operative manner such that the arc is guided into the chutes thereby achieving rapid arc quenching.

Title of Invention

DOUBLE BREAK CONTACT ARRANGEMENT FOR MINIATURE CIRCUIT BREAKERS

Abstract

The present invention relates to a contact system for breaking current into plurality of arcs ensuring double arc length. The contact system comprises housing (6), plurality of contact members which comprises fixed and moving contact members (2, 3). The fixed and moving contact members (2, 3) are ergonomically designed to produce high electrodynamic forces. Guide means (4) is operatively connected to the moving contact member (3) by means of a rigid bar means (11) and to support a spring mechanism for compression and/or decompression in ON and/or OFF operation. Arc chutes (10) are placed beneath the fixed contact (2) in an operative manner such that the arc is guided into the chutes thereby achieving rapid arc quenching.

Full Text	F O R M 2 THE PATENTS ACT, 1970 (39 of 1970) & The Patents Rules, 2003 PROVISIONAL SPECIFICATION (See section 10; rule 13) 1. Title of the invention. - "DOUBLE BREAK CONTACT ARRANGEMENT FOR MINIATURE CIRCUIT BREAKERS" 2. Applicant(s) (a) NAME : LARSEN & TOUBRO LIMITED (b) NATIONALITY : An Indian Company (c) ADDRESS : L & T House, Ballard Estate, Mumbai 400 001, State of Maharashtra, India 3. PREAMBLE TO THE DESCRIPTION The following specification describes the invention FIELD OF INVENTION The present invention relates to a contact system for miniature circuit breakers. More particularly, the invention relates to a contact system adapted to break current in two arcs ensuring double arc length in series resulting in rapid arc-quenching achieving a higher breaking capacity by means of translational movement of moving contact means with respect to the fixed contact means inside' miniature circuit breaker. BACKGROUND AND PRIOR ART US4910485 deals with the circuit-breaking arrangement of a low voltage circuit breaker which comprises in each pole a switching bar, a pair of 'fixed contact's connected to terminals, a double-break rotary contact extending in the housing of the bar, and two arc-chutes disposed on each side of the bar. Two contact pressure springs ensure elastic positioning of the rotary contact along the longitudinal direction of the pole. Pivoting of the rotary contact takes place around a fictitious axis mounted floating with respect to the fixed rotation axis of the bar. But this rotational dual-break is only achievable in a moulded case circuit breaker and not in a miniature circuit breaker because of the size constraints applicable. Hence our invention of translational dual-break retains the advantages of a rotary break as well as achieves the purpose in a smaller overall dimension. US6232570 describes a rotary double-break circuit breaker which includes a case defining a circuit breaker enclosure with a rotatable bridge and contact arm arrangement. The 2 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 thereto. Each of the movable contacts includes a heel portion and a toe portion, the heel portion contacting one of the stationary contacts and the toe portion spaced from the stationary contact when the contact bridge is in closed position, the movable contact being angled or curved relative to the stationary contact such that upon the contact bridge rotating to disengage the movable contacts from the stationary contacts, an electric arc formed between the movable contact and the stationary contact runs to the toe portion of the movable contact thereby protecting the heel portion from substantial damage. But this rotational dual-break is only achievable in a moulded case circuit breaker, (same as in case of US Patent No. 4910485) and not in a miniature circuit breaker because of the size constraints applicable. Hence our invention of translational dual-break retains the advantages of a rotary break as well as achieves the purpose in a smaller overall dimension. US5030804 discloses a contact arrangement, particularly intended for current-limiting low voltage circuit breakers, with a double break movable contact arm, the central part of which is attached to an insulating shaft which is rotatably journalled 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. The contact arms have flat shape and are arranged with their broad sides facing each other. The shaft consists of two sleeve-formed holders surrounding the torsion springs. One holder exhibits a 3 stop face for a latching member for arresting the movable contact arm in the open position. Again, this is not suitable for implementing in a miniature circuit breaker and hence our invention of translational dual-break retains the advantages of a rotary break as well as achieves the purpose in a smaller overall dimension. Thus there is a need to provide for a contact system for miniature circuit breakers which breaks the current in two arcs inside the device achieving a higher breaking capacity by means of translational movement of moving contact with respect to the fixed contact. The present inventors have found that the fixed and the moving contacts at a particular disposition give rise to high electrodynamic repulsion force, which entails a rapid contact separation upon a short circuit. The arc length is double that of any conventional single break system which ensures reduction of let-through energy thereby achieving high breaking capacity. OBJECTS OF INVENTION One object of the present invention to provide a contact system for breaking current in two arcs ensuring double arc length in series resulting in rapid arc-quenching. Another object of the present invention is to reduce the let-through energy and achieve high breaking capacity. Yet another object of the present invention is to provide high electrodynamic repulsion forces. 4 Yet another object of the present invention is to ensure rapid contact separation. Yet another object of the present invention is to provide essential contact pressure between moving contact and main spring means. SUMMARY OF INVENTION Thus according to one aspect of the present invention there is provided a contact system for breaking current in two arcs ensuring double arc length thereby reducing let-through energy substantially and achieve high breaking capacity, said contact system comprising : housing; plurality of contact members in said housing wherein the contact members comprises of fixed and moving contact members, said fixed and moving contact member being ergonomically designed and arranged in a manner that there exist a predetermined relationship between the two members so as to produce high electrodynamic forces; guide means operatively connected to said moving contact member by means of a rigid bar means and adapted to support a spring mechanism for compression and decompression in ON and/or OFF operation; and arc chutes being placed beneath the fixed contact in an operative manner such that the arc is guided into the chutes thereby achieving rapid arc quenching. 5 DETAILED DESCRIPTION OF INVENTION The double break contact system of the present invention comprises moving contact member comprising moving contact bridge having contact tips at its ends. Plurality of fixed contact members comprising of two fixed ergonomic contacts U-shaped and operatively and symmetrically to each other. The moving contact bridge is accommodated in a guide means so that a two and fro vertical motion (downward or upward) is possible. The moving and the fixed contacts are operatively arranged such that the at the time of making or breaking contact the fixed and the moving contact are disposed parallely to each other which causes high electrodynamic repulsion forces, which entails a rapid contact separation upon any short circuit even before the- operation of the mechanism. The guide means comprises of main compression spring guide to support the spring mechanism as it compresses and decompresses in ON-OFF operation. Rigid bar means comprises of a bar element so designed that the dead center of the mechanism is just before knob of the circuit breaker moves to final rest position. BRIEF DESCRIPTION OF ACCOMPANYING FIGURES Fig. 1 illustrates the miniature circuit breaker showing the contact system, mechanism, and the tripping magnet. Fig. 2 illustrates the contact system only with the rigid bar which connects the moving contact motion with the main spring. 6 DETAILED DESCRIPTION OF ACCOMPANYING FIGURES Referring to Fig. 1, it shows a 3-D view of the miniature circuit breaker showing the contact arrangement, mechanism, and the tripping magnet. It shows the moving contact bridge 3, with the contact tips at its ends, the U-shaped fixed contacts 2 and the terminal position 1. The figure is showing the contacts in the closed condition. The moving contact 3 moves downwards along the guide 9 on the housing 6 of the proposed MCB when the knob 5 goes from ON to OFF. The main compression spring guide 4 supports the spring as it compresses and decompresses in the ON-OFF operation. The rigid mechanism bar 11 is such designed that the dead centre of the mechanism is just before the knob 5 moves to the final rest position. When the MCB trips, the contacts 3 and 2 part because of the repulsion effect of electric current flowing parallel in opposite directions and simultaneously the hammer hits a trip lever (not shown) which is connected to the pivot point of the compression spring guide 4, and the mechanism de-latches. The arc chutes 10 are placed at two places where the contacts part so that the arc is guided straight into them in the repulsion effect between the two arcs and the quenching is quick. The arc length is double that of the conventional single break system assuming the same contact gap in OFF condition, which ensures substantial reduction of let-through energy, thereby achieving a higher breaking capacity. Thus a much higher breaking capacity can be achieved by using this double break system in the same external dimensions as a conventional single break MCB. 7 Referring to Fig. 2, it shows a 3-D view of the contact arrangement only with the rigid bar, which connects the moving contact motion with the main spring. The arc chutes 10 are placed just where the contacts 2 and 3 part. Due to the self-blast magnetic field as well as the oppositely flowing current repulsion of the two arcs the arcs move into the arc chutes and get quenched. The time taken for quenching the arc also is comparably less than that in case of a conventional single break system, which helps reduce the let-through energy further. Dated this 25th day of March 2006. Abhishek Sen of S. Majumdar & Co Applicant's agent

Full Text

F O R M 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
PROVISIONAL SPECIFICATION
(See section 10; rule 13)
1. Title of the invention. - "DOUBLE BREAK CONTACT ARRANGEMENT FOR MINIATURE CIRCUIT BREAKERS"
2. Applicant(s)
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L & T House, Ballard Estate, Mumbai 400 001, State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification describes the invention

FIELD OF INVENTION
The present invention relates to a contact system for miniature circuit breakers. More particularly, the invention relates to a contact system adapted to break current in two arcs ensuring double arc length in series resulting in rapid arc-quenching achieving a higher breaking capacity by means of translational movement of moving contact means with respect to the fixed contact means inside' miniature circuit breaker.
BACKGROUND AND PRIOR ART
US4910485 deals with the circuit-breaking arrangement of a low voltage circuit breaker which comprises in each pole a switching bar, a pair of 'fixed contact's connected to terminals, a double-break rotary contact extending in the housing of the bar, and two arc-chutes disposed on each side of the bar. Two contact pressure springs ensure elastic positioning of the rotary contact along the longitudinal direction of the pole. Pivoting of the rotary contact takes place around a fictitious axis mounted floating with respect to the fixed rotation axis of the bar. But this rotational dual-break is only achievable in a moulded case circuit breaker and not in a miniature circuit breaker because of the size constraints applicable. Hence our invention of translational dual-break retains the advantages of a rotary break as well as achieves the purpose in a smaller overall dimension.
US6232570 describes a rotary double-break circuit breaker which includes a case defining a circuit breaker enclosure with a rotatable bridge and contact arm arrangement. The
2

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 thereto. Each of the movable contacts includes a heel portion and a toe portion, the heel portion contacting one of the stationary contacts and the toe portion spaced from the stationary contact when the contact bridge is in closed position, the movable contact being angled or curved relative to the stationary contact such that upon the contact bridge rotating to disengage the movable contacts from the stationary contacts, an electric arc formed between the movable contact and the stationary contact runs to the toe portion of the movable contact thereby protecting the heel portion from substantial damage. But this rotational dual-break is only achievable in a moulded case circuit breaker, (same as in case of US Patent No. 4910485) and not in a miniature circuit breaker because of the size constraints applicable. Hence our invention of translational dual-break retains the advantages of a rotary break as well as achieves the purpose in a smaller overall dimension.
US5030804 discloses a contact arrangement, particularly intended for current-limiting low voltage circuit breakers, with a double break movable contact arm, the central part of which is attached to an insulating shaft which is rotatably journalled 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. The contact arms have flat shape and are arranged with their broad sides facing each other. The shaft consists of two sleeve-formed holders surrounding the torsion springs. One holder exhibits a
3

stop face for a latching member for arresting the movable contact arm in the open position. Again, this is not suitable for implementing in a miniature circuit breaker and hence our invention of translational dual-break retains the advantages of a rotary break as well as achieves the purpose in a smaller overall dimension.
Thus there is a need to provide for a contact system for miniature circuit breakers which breaks the current in two arcs inside the device achieving a higher breaking capacity by means of translational movement of moving contact with respect to the fixed contact.
The present inventors have found that the fixed and the moving contacts at a particular disposition give rise to high electrodynamic repulsion force, which entails a rapid contact separation upon a short circuit. The arc length is double that of any conventional single break system which ensures reduction of let-through energy thereby achieving high breaking capacity.
OBJECTS OF INVENTION
One object of the present invention to provide a contact system for breaking current in two arcs ensuring double arc length in series resulting in rapid arc-quenching.
Another object of the present invention is to reduce the let-through energy and achieve high breaking capacity.
Yet another object of the present invention is to provide high electrodynamic repulsion forces.
4

Yet another object of the present invention is to ensure rapid contact separation.
Yet another object of the present invention is to provide essential contact pressure between moving contact and main spring means.
SUMMARY OF INVENTION
Thus according to one aspect of the present invention there is provided a contact system for breaking current in two arcs ensuring double arc length thereby reducing let-through energy substantially and achieve high breaking capacity, said contact system comprising :
housing;
plurality of contact members in said housing wherein the
contact members comprises of fixed and moving contact members,
said fixed and moving contact member being ergonomically
designed and arranged in a manner that there exist a
predetermined relationship between the two members so as to
produce high electrodynamic forces;
guide means operatively connected to said moving contact
member by means of a rigid bar means and adapted to support a
spring mechanism for compression and decompression in ON
and/or OFF operation; and
arc chutes being placed beneath the fixed contact in an
operative manner such that the arc is guided into the chutes
thereby achieving rapid arc quenching.
5

DETAILED DESCRIPTION OF INVENTION
The double break contact system of the present invention comprises moving contact member comprising moving contact bridge having contact tips at its ends. Plurality of fixed contact members comprising of two fixed ergonomic contacts U-shaped and operatively and symmetrically to each other. The moving contact bridge is accommodated in a guide means so that a two and fro vertical motion (downward or upward) is possible. The moving and the fixed contacts are operatively arranged such that the at the time of making or breaking contact the fixed and the moving contact are disposed parallely to each other which causes high electrodynamic repulsion forces, which entails a rapid contact separation upon any short circuit even before the- operation of the mechanism. The guide means comprises of main compression spring guide to support the spring mechanism as it compresses and decompresses in ON-OFF operation. Rigid bar means comprises of a bar element so designed that the dead center of the mechanism is just before knob of the circuit breaker moves to final rest position.
BRIEF DESCRIPTION OF ACCOMPANYING FIGURES
Fig. 1 illustrates the miniature circuit breaker showing the contact system, mechanism, and the tripping magnet.
Fig. 2 illustrates the contact system only with the rigid bar which connects the moving contact motion with the main spring.
6

DETAILED DESCRIPTION OF ACCOMPANYING FIGURES
Referring to Fig. 1, it shows a 3-D view of the miniature circuit breaker showing the contact arrangement, mechanism, and the tripping magnet. It shows the moving contact bridge 3, with the contact tips at its ends, the U-shaped fixed contacts 2 and the terminal position 1. The figure is showing the contacts in the closed condition. The moving contact 3 moves downwards along the guide 9 on the housing 6 of the proposed MCB when the knob 5 goes from ON to OFF. The main compression spring guide 4 supports the spring as it compresses and decompresses in the ON-OFF operation. The rigid mechanism bar 11 is such designed that the dead centre of the mechanism is just before the knob 5 moves to the final rest position. When the MCB trips, the contacts 3 and 2 part because of the repulsion effect of electric current flowing parallel in opposite directions and simultaneously the hammer hits a trip lever (not shown) which is connected to the pivot point of the compression spring guide 4, and the mechanism de-latches. The arc chutes 10 are placed at two places where the contacts part so that the arc is guided straight into them in the repulsion effect between the two arcs and the quenching is quick. The arc length is double that of the conventional single break system assuming the same contact gap in OFF condition, which ensures substantial reduction of let-through energy, thereby achieving a higher breaking capacity. Thus a much higher breaking capacity can be achieved by using this double break system in the same external dimensions as a conventional single break MCB.
7

Referring to Fig. 2, it shows a 3-D view of the contact arrangement only with the rigid bar, which connects the moving contact motion with the main spring. The arc chutes 10 are placed just where the contacts 2 and 3 part. Due to the self-blast magnetic field as well as the oppositely flowing current repulsion of the two arcs the arcs move into the arc chutes and get quenched. The time taken for quenching the arc also is comparably less than that in case of a conventional single break system, which helps reduce the let-through energy further.

Dated this 25th day of March 2006.

Abhishek Sen
of S. Majumdar & Co
Applicant's agent

Documents:

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Patent Number

271106

Indian Patent Application Number

445/MUM/2006

PG Journal Number

06/2016

Publication Date

05-Feb-2016

Grant Date

03-Feb-2016

Date of Filing

27-Mar-2006

Name of Patentee

LARSEN & TOUBRO LIMITED

Applicant Address

L & T HOUSE, BALLARD ESTATE, MUMBAI.

Inventors:

#	Inventor's Name	Inventor's Address
1	BURA, VIRENDER SINGH	SWITCHGEAR DESIGN & DEVELOPMENT CENTER, LARSEN & TOUBRO LIMITED, ELECTRICAL SECTOR-(EBG), POWAI WORKS (EAST), GATE NO. 7, SAKI VIHAR ROAD, MUMBAI-400 072.
2	NANDI, SHUVABRATA	SWITCHGEAR DESIGN & DEVELOPMENT CENTER, LARSEN & TOUBRO LIMITED, ELECTRICAL SECTOR-(EBG), POWAI WORKS (EAST), GATE NO. 7, SAKI VIHAR ROAD, MUMBAI-400 072.

PCT International Classification Number

H01H1/22

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA