| 摘要 |
PURPOSE: To house a power supply circuit, a DC sensor and a tripping device in a circuit breaker, by a method wherein a line current signal is outputted to a photocoupler by a pulse width modulator and is inputted to a pulse width demodulator by the photocoupler, and a real sensing current value formed by the demodulator is inputted to the tripping device. CONSTITUTION: A sensing signal Vdc is modulated into a pulse width modulation signal and is transmitted to a photocoupler PHT. The transmitted pulse width modulation signal is demodulated into a sensing current signal and is supplied to a line 4. If a power supply circuit applies a square wave voltage to a primary winding W1, a square wave current is induced in a secondary winding W2 and is supplied to a rectifier RCT which generates a fundamental voltage V. If a secondary winding W3 supplies a square wave current to the rectifier RCT, the rectifier RCT supplies the fundamental voltage to a pulse width modulator MOD. |
