Trip control circuit for circuit breaker

A trip control circuit for a circuit breaker, the trip control circuit comprising:

• a current transformer that has a ring-shaped core allowing a circuit to pass through and a secondary coil wound around the core for detecting a current flowing on the circuit and providing a current detection signal;
• an oscillation circuit section that configured to apply an electrical signal to the secondary coil of the current transformer to increase a slope of a hysteresis loop of the current transformer to allow the secondary coil to detect a DC current, as well as an AC current, flowing on the circuit;
• and
• a trip determining circuit section that configured to compare a current value indicated by the current detection signal having an AC component and a DC component output from the secondary coil of the current transformer with a predetermined reference current value, and output a trip control signal when the current value indicated by the current detection signal exceeds the reference current value.