WO2014020410A2

WO2014020410A2 - A compact circuit breaker and switchgear thereof

Info

Publication number: WO2014020410A2
Application number: PCT/IB2013/001670
Authority: WO
Inventors: Bhushan KULKARNI; Subbaiahthever DUKKAIAPPAN; Babu SANKAR; Hrishikesh S BRAMHAPURIKAR; V Ramesh
Original assignee: Abb Technology Ltd
Priority date: 2012-07-31
Filing date: 2013-07-31
Publication date: 2014-02-06
Also published as: CN104737396A; CN104737396B; WO2014020410A3; MY174993A

Abstract

The invention relates to a compact circuit breaker having a plurality of contacts. The circuit breaker comprises one set of contacts having one or more contacts and other set of contacts having one or more contacts, where the one set of contacts is mounted at an angle to the other set of contacts.

Description

A COMPACT CIRCUIT BREAKER AND SWITCHGEAR THEREOF

FIELD OF INVENTION

The present invention relates to circuit breakers and more particularly to a compact circuit breaker having contacts which are at an angle to the axis of the circuit breaker pole.

BACKGROUND OF THE INVENTION

In electrical systems, circuit breakers play an integral role. Circuit breakers protect electrical circuits from damage caused by overload or short circuit. This is done by detecting fault conditions and by breaking the electrical circuit to discontinue electrical flow.

When the electrical circuit is broken, the current in the circuit often creates an arc having extremely high temperatures. Such arcs are potentially harmful to the electrical circuit. To tackle this issue, the circuit breaker breaks the electrical circuit by connecting itself to the electrical circuit and by forcing the current to flow into it. In such a situation the arc is created inside the circuit breaker, where the circuit breaker can extinguish the arc without any harm to the electrical circuit. The circuit breaker connects to the electrical circuit using its contact arms, which have contacts mounted at the ends of the contact arms.

In the conventional design of circuit breaker the contact arms are long and parallel to each other. Due to long contact arms, the circuit breaker occupies a large area of space. Additionally due to long arms, cost of material is also high. The long contact arms also leads to a longer current flow path which contributes to power loss and excess material usage. Due to the parallel arrangement of contact arms, the contact arms experience electromagnetic forces, leading to structural weakness.

Therefore there is a need for a compact circuit breaker which is cost effective and has improved structural strength. OBJECTS OF THE INVENTION

It is an object of the invention to provide a compact circuit breaker.

Another object of the invention is to provide a compact circuit breaker which is cost effective.

Also another object of the invention is to provide a compact circuit breaker having improved structural strength.

Yet another object of the invention is to provide a compact circuit breaker which is easy to assemble.

Further object of the invention is to provide a compact circuit breaker having a shorter current path.

SUMMARY OF THE INVENTION

The invention provides a circuit breaker having a plurality of contacts where the circuit breaker comprises one set of contacts and other set of contacts. The one set of contacts from the plurality of contacts has one or more contacts and is mounted at an angle to the other set of contacts from the plurality of contacts. The other set of contacts has one or more contacts.

The invention also provides for a switchgear comprising the circuit breaker of the invention, where the one set of contacts is electrically connectable to the corresponding set of contacts of the busbars, or is electrically connectable to the corresponding set of contacts of the current transformer. The invention also provides a similar switchgear using the circuit breaker of the invention, where the said other set of contacts is electrically connectable to the corresponding set of contacts of the busbars, or is electrically connectable to the corresponding set of contacts of the current transformer. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram of a conventional circuit breaker according to prior art. Fig. 2 is a schematic diagram of a circuit breaker according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a compact circuit breaker which is cost effective and has improved structural strength. The invention is explained using an exemplary embodiment and is not limited to the same.

Fig. 1 shows a conventional circuit breaker 100 according to the prior art. The circuit breaker 100 consists of a circuit breaker pole 110, two contact arms 120 and 130 located on the circuit breaker pole 100 and two contacts 125 and 135 located on the contact arms 120 and 130 respectively. When the circuit breaker 100 becomes active, the circuit breaker pole 1 10 moves in a horizontal manner towards the contacts of the electrical circuit. This causes the contacts 125 and 135 of the circuit breaker 100 come into contact with the contacts of the electrical circuit, breaking the circuit and forcing the current to flow into the circuit breaker 100 which is capable of handling the arc created by the disruption of the current flow.

As seen from the circuit breaker 100, the size of the circuit breaker is directly proportional to the length of the contact arms. Hence the conventional circuit breaker which has long contact arms, occupies more space. Additionally when contact arms of the circuit breaker are long, the cost of material is also high. The long contact arms also leads to a longer current flow path which contributes to power loss and excess material usage. Moreover in the conventional circuit breaker the contact arms are parallel to each other, which cause the contact arms to experience electromagnetic forces when current flows through them. These electromagnetic forces weaken the structural integrity of the housing in which the pole is located.

The invention overcomes all these problems by modifying the circuit breaker. Fig. 2 shows a circuit breaker 200 according to the invention. The circuit breaker 200 comprises a circuit breaker pole 210, contacts 230 and 220 mounted directly on the circuit breaker pole 210, and a moving arrangement. The contacts 220 and 230 are mounted on the circuit breaker pole 210 in such a manner that the contacts are at an angle to each other. In the exemplary embodiment, the contacts are positioned perpendicular to each other. The circuit breaker 200 of the invention has a moving arrangement to move itself. In the exemplary embodiment, this moving arrangement is shown by a racking screw 250, racking mechanism 260 and an integrated frame with wheels 240. By rotating the racking screw 250 in clockwise or anti-clockwise manner, the operator can move the circuit breaker 200. Upon activation, the circuit breaker 200 moves in a horizontal manner towards the contacts of the electrical circuit. The contacts 220 and 230 engage with the corresponding contacts of the electrical circuit. This results in a disconnection of the electrical circuit, forcing the current to flow into the circuit breaker 200 which suitably handles the arc created by it.

This novel and inventive construction of the circuit breaker makes the circuit breaker more compact. Also by removing the contact arms of the circuit breaker, the cost of material is also reduced, the cost effectiveness of the circuit breaker is improved. As there are less number of components, the assembly process is simplified. This also reduces the chances for incorrect assembly. By reducing the size of the circuit breaker and by removing the contact arms of the circuit breaker, the current carrying path is also reduced. This helps in improving the efficiency, reducing power loss, improving thermal life and reducing material usage. Also by keeping the contacts at an angle to each other, the resultant magnetic forces acting upon the contacts is also reduced. This results in improved structural strength of the housing of the circuit breaker pole.

Hence the inventions provides a compact circuit breaker which is cost effective, easy to assemble, has improved structural strength and shorter current path.

Claims

I / WE CLAIM:

1. A circuit breaker having a plurality of contacts, the said circuit breaker comprising: one set of contacts from the said plurality of contacts, the said one set of contacts having one or more contacts; and

other set of contacts from the said plurality of contacts, the said other set of contacts having one or more contacts

wherein the said one set of contacts is mounted at an angle to the said other set of contacts.

2. The circuit breaker as claimed in claim 1, wherein the said one set of contacts is perpendicular to the said other set of contacts.

3. The circuit breaker as claimed in claim 1, wherein the said one set of contacts includes one or more of tulip contacts or slidable contacts or both.

4. The circuit breaker as claimed in claim 1, wherein the said other set of contacts includes one or more of tulip contacts or slidable contacts or both.

5. The circuit breaker as claimed in claim 3 or 4, wherein the said slidable contacts comprises contacts slidable over the corresponding set of contacts.

6. The circuit breaker as claimed in any one of the preceding claims, wherein the said circuit breaker is movable.

7. The circuit breaker as claimed in claim 7, wherein the said circuit breaker includes moving arrangements to move the said circuit breaker.

8. A switchgear comprising a circuit breaker as claimed in any one of the preceding claims, wherein the said one set of contacts is electrically connectable to the corresponding set of contacts of the busbars, or is electrically connectable to the corresponding set of contacts of the current transformer.

9. A switchgear comprising a circuit breaker as claimed in any one of the claims 1 to 7, wherein the said other set of contacts is electrically connectable to the corresponding set of contacts of the busbars, or is electrically connectable to the corresponding set of contacts of the current transformer.