| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent a current exceeding specified value from flowing to the secondary winding 24b of a coupling transformer 24 at turn-on of a main current switch 26. SOLUTION: This power unit has a chopper circuit 10 which switches the output currents of DC power sources 6 and 8, a means which supplies the output voltage to the first electrode 32a of a plasma arc fusion furnace via the winding 24b of the coupling transformer 24 constituting a high-frequency high voltage generating circuit 20' and also supplies it to the second electrode 32b and an electrode 34 at the bottom of a furnace, a main current switch 26 which is connected in parallel with the winding, and a current detector 64 which detects the magnitude of the current flowing in the winding. When the magnitude of the current detected with the current detector at ON of the main current switch gets over a specified value, control means 16 and 18 stop the action of the above chopper circuit thereby putting it in break state.</p> |
