Electrical safety circuit for plasma-arc cutting appliances

摘要

In known plasma-arc cutting appliances, a high rectified output voltage for generating the cutting arc between the cutting torch and workpiece is applied. A circuit which, with the arc extinguished, avoids dangerous contact voltages for operators is to be specified. For this purpose, a safety circuit senses the applied output voltage via a detector circuit. Provided in the detector circuit is a threshold stage which, when a predeterminable voltage value of the output voltage is exceeded, actuates a breaker located in the control circuit of the cutting appliance and switching off the output voltage. The safety circuit can be used in plasma-arc cutting appliances.