Selection of DC circuit breaker

Generally speaking, when choosing a DC circuit breaker, the main factors to be considered are the basic parameters such as rated working voltage, rated current, tripping set current and voltage and current of shunt and undervoltage trip.

l. According to the normal load current of the DC circuit, initially select the circuit breaker of the corresponding specification and model.

2. According to the rated voltage of the DC power supply, the grounding method (Type A, B, C) and the calculated short-circuit current value, finally determine the number of stages and the wiring method of the circuit breaker. The specific determination method is as follows:

For type A (negative ground) system: Determine the number of poles in series for the positive pole according to the power supply voltage and the calculated short-circuit current that needs to be broken. Considering the insulation isolation of the negative pole, an additional pole must be connected to the negative pole of the circuit breaker.

For type B (center point grounding) system: multiply the power supply voltage by one-half to obtain the voltage applied to the positive and negative poles, and use this voltage and the short-circuit current to be broken to determine the circuit breaker whose positive and negative poles need to be connected in series Number of poles.

For type C (both positive and negative poles are not grounded) system: determine the required number of circuit breaker poles based on the power supply voltage and the short-circuit current that needs to be broken. , Evenly distribute the number of poles obtained in the positive and negative poles respectively in series.

3. The rated working voltage Ue and rated current Ie of the DC circuit breaker. It should be no lower than the normal rated working voltage and working current or calculated current of the line and equipment respectively. The rated working voltage of a circuit breaker is related to the making and breaking capacity and usage category. The same circuit breaker product can have several rated working voltages and corresponding making and breaking capacities and usage categories.