What is the breaking capacity of the circuit breaker and how to choose?

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(Last Updated On: 2020年11月24日)

Introduction of breaking capacity of circuit breaker

The breaking capacity of a circuit breaker refers to the maximum short-circuit current value that the circuit breaker can break in the event of a short-circuit fault without any damage to the circuit breaker, which is a protective function of the circuit breaker switch.

Breaking capacity refers to a special function of the circuit breaker switch and it refers to the ability to cut off the fault current safely and also the most important factor on price and is not necessarily related to its current rating.

How to select different breaking capacities in different environments.

Breaking capacity is the main technical indicators of the circuit breaker, and also represents the technical level of the brand, so the higher the breaking capacity of the same type of circuit breaker, the more secure for the safety of electricity.

Generally speaking, the breaking capacity of circuit breakers is selected according to the calculation of the expected short-circuit current of the line.

1- residential buildings, small shopping malls and public buildings,

In this condition, which is powered by the low-voltage grid of the local power supply department, the cable or overhead conductor cross-section of the power supply line is thin, and the distance of the electrical equipment from the power supply is far, a circuit breaker with a breaking capacity of 4.5kA and above should be used.

2.- For users with dedicated supply or 10kV substation

This is often due to the coarser cable plane of the power supply line, the power supply distance is shorter, 6kA and above rated breaking capacity circuit breakers should be used.

Above all, different environments could choose the different breaking capacity of circuit breakers. We usually choose the breaking capacity below 6KA in the household use, while in the substation and another biding, we should choose above 6KA to ensure safety.

4.5&6KA Breaking Capacity
10KA Breaking Capacity

Product Features

Excellent current limiting, short time in burning arcing, high breaking capacity, accurate protection, long service life, reliable performance

Housing designed with cambered surface, pipeline type ventilating slot on the side, improve the capacity of heat dissipation and prevent product from temperature rising

Obvious indicator of contact position state

1P+N and 3p+N, N pole can be breaking

Terminal blocks can be connected with copper bar and conductive wire.

Complete accessories with auxiliary contact, alarm contact, shunt release, under-voltage release, over-voltage release, over and under-voltage release, etc.

Different breaking capacity at different voltage environment.

The breaking capacity of circuit breaker is divided into:

1.1 Limit short-circuit breaking capacity Icu: After breaking the short-circuit current, the circuit breaker is not required to carry the rated current, which means it needs to be replaced with a new circuit breaker.

1.2 Operational short-circuit breaking capacity Ics: After breaking the short-circuit current of the circuit breaker, it can still carry the rated current, that is, it can continue to be used without replace a new circuit breaker.

Ics can be expressed as Ics percent:

Standard Ratios between Ics and Icu
Standard Ratios between Ics and Icu

For example, the ultimate short-circuit breaking capacity of a circuit breaker Icu is 100kA, then the operating short-circuit breaking capacity Ics is 75% of Icu, that is, 75kA, the circuit breaker in the customer’s field operation, due to a three-phase short-circuit fault occurred at the load side, the fault current is about 100kA, then the circuit breaker can not be used after breaking, if the short-circuit fault current occurs in the field 75kA or less, the circuit breaker can also break the fault current, but can continue to use.

The corresponding breaking capacity values are different for 220V, 440V, 525V, 690V, and generally the same low-voltage circuit breaker, the higher the voltage level, the lower the short-circuit breaking capacity.

Conclusion

The breaking capacity of a circuit breaker is the most factor of a circuit breaker, different environment, you should choose different breaking capacity for your security. Fachine circuit breaker is your excellent choice with high breaking capacity.

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