| 摘要 |
<p>In arc welding, esp. in hazardous conditions, e.g. in a confined space, the power supply uses a transformer with a sec. circuit into which a rectifier stack can be switched. Under no-load conditions, the rectifier is connected in the sec. circuit, but is automatically cut out at the start of welding without interrupting the a.c. welding current. The rectifier can pref. be bridged over by a by-pass circuit contg. a controlled switch, esp. a thyristor. Used esp. for welding inside boilers, where the max. permissible effective a.c. voltage under no load is 42 V, but it is sometimes difficult to strike the arc, e.g. when using TIG welding with low currents. The max. permissible d.c. voltage is 100 V, and the invention exploits this fact for striking the arc.</p> |
