Starting circuit for switch drive operated by three=phase AC - has triac and glow discharge lamp whose ignition voltage determines triac ignition

摘要

The switch is monitored by direct current. Monitoring contacts dependent on the switch position are in series with a motor winding each. A circuit part is inserted between the motor winding disconnected by the monitoring contact and the other two windings. It passes the driving current but blocks the monitoring current. The circuit part contains a triac (T) and a glow discharge lamp (G) whose ignition voltage determines the phase of the triac (T) ignition. The glow discharge lamp is connected between a resistor (R) and a capacitor (C1).