Classification of circuit breaker
Classification of power breaker according to poles:
According to poles, circuit breaker can be classified as 2 pole circuit breaker, 3 pole circuit breaker and 4 pole circuit breaker. And there are following four types for neutral N pole in 4 pole circuit breaker.
A type : N pole is not to be connected with over-current shunt trip. This N pole is always connected and do not make or break with other 3 poles.
B type: N pole is not to be connected with over-current shunt trip. This N pole make and break with other three poles( this N pole is to first make and then to break)
C type: N pole is connected with over-current shunt trip and make and break with other three poles(this N pole is to make first and then to break)
D type: N pole is to be connected with over-current shunt trip. It is always connected and does not make or break with other three poles.
There are different amperes for circuit breaker, 6A 10A 16A 20A 25A 32A 40A 50A 63A 80A 100A 125A 140A 160A 180A 200A 225A 250A 325A 400A 500A 630A 800A 1000A and so on.
There are three types for wire connection: front panel connection, back panel connection and plug in type connection.
Classification of electrical breakers according to over-current shunt trip:
According to different over-current shunt trip, there are thermodynamic-electromagnetic(complex)type and electromagnetic(transient)type.
Circuit breaker can work with auxiliaries or without auxiliaries. Auxiliaries divided into internal auxiliaries and external auxiliaries. For internal auxiliaries, there are Shunt release, under-voltage release, auxiliary contacts, and alarm contacts.
For external auxiliaries, there are Rotary handle operation mechanism, electric operation mechanism, chain mechanism and auxiliary device wiring terminal row, etc.
Circuit breaker for 1KV and below is called low voltage circuit breaker, such as frame style circuit breaker, molded case circuit breaker and miniature circuit breaker. Rated ampere of frame style circuit breaker ranges from 630A to 6300A. Rated amp of molded case circuit breaker ranges from 63A to 1600A. And rated amp of mini circuit breaker ranges from 0.3A to 125A.
Low voltage circuit breaker adopts open-type structure and to be mounted on metal bracket. All components are designed for convenient maintenance, examination and replacement.
Tripping element is of big adjusting range and can exchange within framed specifications. Tripping element can be electromagnetic-over-current direction action type or static tripping type.
Low voltage circuit breaker can be assembled with current limiting fuse to constitute drawer structure to meet the requirements of breaking current up to 200KA(symmetric effective value). And the fuse, as a part of the circuit breaker, combines with multi-phased mechanical interlocks to cancel out the possibility of single phase running.
Die casting case circuit breaker is a kind of switch to be assembled with automatic protective device in the holistic case made of insulation material. It has following general types.
- Thermo-magnetic type: there are thermal element for overload protection and instantaneous electromagnetic tripping element for short circuit protection.
- Electromagnetic type: there is only instantaneous tripping element to be used where only requires short circuit protection.
- Die casting case type with fuse: there are common thermo-magnetic protective device for short circuit and overload protection; and current limiting fuse to protect from bigger short circuit fault.
- High break flow type: compared with standard structure and thermo-magnetic circuit breaker without fuse, it can be used to protect from bigger short circuit and does not need to increase space. It has strong contacts and operating mechanism and strong mold processing case.
Circuit breaker of less than 1KV always break fault current more quickly then high voltage circuit breaker. In current designs, contacts of circuit breaker of less than 1KV begin to break during the first cycle of short circuit. Thus circuit breaker must be calibrated by the asymmetrical current of first cycle the biggest breaking. But circuit breakers of less than 1KV is to be calibrated by symmetrical current. It does not need multiply by DC component compensation coefficient to decide the rated value of the equipment. Thus, instantaneous bearing is the same as breaking capacity.
Circuit breaker must can close, carry and break the possible biggest fault current arise at the assembling place. To choose circuit breaker, the most important thing is that the interrupt short circuit current of circuit breaker is to be smaller than possible short circuit current arise at the assembling place.