Selection of Circuit Breaker for Power Supply Protection

• The current to a controller should flow as three time as much at the maximum during acceleration and deceleration. Select one that would not trip when this much current flows. Select a breaker with the rated current one rank higher in case it trips. (Check the performance in the operation characteristics curve shown in a product catalog.)
• Select a breaker that would not trip with inrush current. (Check the performance in the operation characteristics curve shown in a product catalog.)
• For the rated cutoff current, select a current value that can be cut off certainly even if short-circuit current flows.
  Rated cutoff current > Short-circuit current = Primary power amperage / Power voltage
• Select a circuit breaker with margin to the rated current.
  Circuit breaker rated current > Motor power amperage [VA] / AC input voltage * Safety margin (1.2 to 1.4)

• A clear purpose is necessary when selecting a leakage breaker such as to protect from fire or protection of personnel.
• As the leak current may vary depending on the motor wattage, cable length and ambient environment, it is required to have a measurement of leak current at the point to install a leakage breaker when a leakage protection measure is to be taken.
• For leakage breaker, use a high frequency applicable type.