| 摘要 |
<p>A high frequency, high voltage starting circuit for a plasma arc cutting torch (18) is constructed and operated with isolation between a pilot arc circuit (44) and a transfer arc circuit (42). The duration and value of the energy flow in the pilot arc (12) after initiating the HFHV signal are controlled electronically. The maximum value is sufficient to initiate and support the pilot arc (12) and its transfer. The duration is sufficiently long to allow the pilot arc (12) to transfer, but sufficiently short than nozzle wear is reduced. In the preferred form both circuits have a common D.C. power supply (24) and independent surge injector circuits (32) each formed by of a resistor and surge capacitor connected in parallel with the power supply (24). An L-C loop in the pilot arc circuit maintains a generally constant current output on discharge.</p> |
