| 摘要 |
Method and auxiliary power source in plasma arc welding in order to strike a stable pilot arc. An electrical voltage is fed from an auxiliary power source 10 between the poles A, B of the pilot arc of a plasma arc torch. The voltage of the auxiliary power source consists of a pulsating direct current voltage Uk, the frequency of which is selected from within the audio frequency range 800 Hz B 6 kHz. The arc current Ik that is generated by the auxiliary power source and the arc voltage are set so low that the method is also suitable for micro-plasma welding. In the auxiliary power source 10 there is a rectifier unit 13, a transformer 19 and semiconductor couplings 16a, 16b. Coupled to the secondary coil 19c of the said transformer 19 is a rectifier unit 20, to the coils of which an LC circuit is coupled, which serves to actively maintain the pilot current, the circuit comprising a shunt capacitor 23 and a series coil 24 as filter capacitors. <IMAGE>
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