| 摘要 |
A power supply has a full-wave rectified signal which is alternately switched between a low impedance path, which does not provide power to the power supply, and a charging path, which does provide power to the power supply. During the major portion of the a.c. cycle, the full-wave rectified signal follows the low impedance path without loading the current transformer (12) or distorting the current signal. Near the zero crossings of the a.c. current signal, the low impedance path is opened so that the full-wave rectified signal charges a charging circuit (20) which feeds a voltage regulator (22) to provide output power from the power supply. While the rectified signal flows through the low impedance path, the charging circuit (20) discharges and provides the power required by the peripheral circuitry of the circuit breaker. When the charge in the charging circuit (20) drops below a predetermined set point, which is governed by the output of the regulator (22) and feedback from the rectified signal, power is diverted from the low impedance path to recharge the charging circuit (20). |
