| 摘要 |
A protective circuit for a wire-feed control system of a welding apparatus is described in which a p-gate thyristor is connected in parallel with a direct-current motor which is fed from a thyristor-half-controlled bridge and can be adjusted in its speed via a wire-feed controller, and a closing contact of a relay which can be activated via the torch switch-on contact of the apparatus lies in each gate section of the two bridge thyristors. To avoid a short circuit when switching the torch on again before the motor of the wire-feed control system slows down to a stop, a resistor is connected as a protective measure in the cathode section of the thyristor, with which resistor the base-emitter section of a transistor is connected in parallel, in the collector section of which transistor a second relay and a break contact of the second relay are connected in series with the first relay.
|
