Power supply circuit and electric device

A circuit breaker configured to trip in response to a low voltage condition of a power supply bus, the circuit breaker comprising:

• an electromagnetic actuator having an actuation coil and a movable contact, the electromechanical actuator configured to drive a movable member of the electromagnetic actuator to move in response to an excitation current flowing through the actuation coil, the movable member configured to cause the movable contact to move, thereby implementing a tripping or a closing operation of the circuit breaker;
• a first capacitor characterized by a first withstand voltage value less than a maximum specified voltage of the power supply bus and configured to store electrical charge for supplying a first part of the excitation current to the actuation coil;
• a first switch connected in series with the first capacitor, the first switch configured to implement charging of the first capacitor by the power supply bus and discharging of the first capacitor to provide the first part of the excitation current to the actuation coil;
• a second capacitor characterized by a second withstand voltage value greater than the maximum specified voltage of the power supply bus and configured to store electrical charge for supplying a second part of the excitation current to the actuation coil;
• and
• a control circuit configured to:
• cause the first switch to close in response to the voltage detected being less than a set threshold, the control circuit further configured to cause the first switch to open in response to the voltage detected being greater than the set threshold;
• and
• cause the first and second parts of the excitation current to flow, from the first and second capacitors, respectively, through the actuation coil, in response to the low voltage condition of the power supply bus being detected.