DETECTION OF ARC DISCHARGE

摘要

PURPOSE: To detect arc discharge by monitoring the change of the load voltage between electrodes and the change of the voltage drop of the current-limiting resistor in a power supply device from glow discharge to arc discharge in a vacuum tank on the basis of the change of the load voltage and that of the voltage drop. CONSTITUTION: The voltage corresponding to the voltage drop VR corresponding to a load current Ic is detected as the voltage drop generated by a load current detecting resistor LR1 on the basis of the correlation between the voltage drop VR and load voltage Vc in an arc detection circuit and the voltage corresponding to the load voltage Vc is detected as the load voltage divided by load voltage detecting resistors R1, R2. The displacement of VR and that of Vc are compared by a comparator circuit to detect the change from the relation of 'VR<>Vc' to detect the transition from glow discharge to arc discharge and an arc detection signal is outputted to a power supply operation control circuit.