Circuit breaker tripping curve introduced

Thu Nov 29 13:38:43 CST 2018

Circuit breaker tripping common thermal release, hydraulic - electromagnetic release, electronic release and so on. Tripping characteristic curve is measured at the specified temperature. Release characteristics should indicate the temperature. Tripping characteristic curve on the left is not tripping area, belonging to normal work; right and above the tripping area, belonging to the non-normal operation; the middle of the two lines for the delay tripping area (left line is not Tripping current, right line tripping current). 


The tripping curve reflects the tripping time of the circuit breaker under the specified operating conditions as a function of the expected current. This curve is also called the time-current curve. A total of A, B, C, D four categories.

  A type of curve: the release of tripping current is 2 to 3 times the left curve is not tripping current 2In, the right curve is the tripping current 3In; for the protection of semiconductor electronic circuits with low-power power transformer The measuring circuit or the line is long and the current is small system.


 Class B curve: tripping current triples 3 to 5 times the left curve is not tripping current 3In, the right curve is the tripping current 5In; for short-circuit current protection of small loads.

 C type curve: release current trip 5 to 10 times the left curve is not tripping current 5In, the right curve is the tripping 

current 10In; for distribution protection circuit and has a higher connection Current lighting circuit.


Class D curve: release current of 10 to 20 times, the left curve is not tripping current is 10In, the right curve is the tripping current of 20In; suitable for protection of equipment with high impact current, such as Motors, transformers, solenoid valves and so on. When selecting circuit breakers, the requirements of the equipment to be protected should be met. In the event of a line failure, a fault occurs near the protective circuit breaker action, while the superior circuit breaker does not move, so as not to affect the normal operation of other electrical appliances.

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