Delayed first half wave

In addition to the well-known parameters for the welding process, you will often find the parameter 1st delayed half-wave in the 50/60 Hz systems. The meaning of this setting is explained below.

When a welding transformer is switched on at zero crossing of the voltage or at a smaller ignition delay angle than that of the phase angle between voltage and current, a transient DC component occurs which decays periodically. In this case, the magnetising current is many times higher than in the steady state. In extreme cases, this can destroy the thyristors or the welding transformer. For the actual welding is disadvantageous in any case. To avoid this effect, there is the delayed half-wave setting.

To do this, the onset time of the first half-wave is set to an ignition delay angle that is greater than the phase angle (about 70 to 90 degrees). For seam units and controls with pulses, an extension is available for setting the delayed first half-wave after the pause time. In the basic setting, the delayed half-wave is set on our controllers in such a way that no problems can occur under normal circumstances.

You can find more information about this in our operating instructions and, of course, from your Harms & Wende partner.