Energising circuit for mains voltage electromagnetic switch controlling e.g. washing machine - has two parallel-connected semiconductor switches in series with capacitor which is charged and discharged during positive and negative half cycles

摘要

The electromagnetic switch drive circuit has a semiconductor switch in series with the relay coil, controlled by an electronic circuit. The semiconductor switch is formed by two semiconductor switches, e.g. triacs with series diodes (D1, T1; T2, D2), in parallel, one for the positive and the other one for the negative half-cycles of the mains a.c. voltage. The parallel semiconductor switches are connected in series with a capacitor (C), charged by the mains frequency via one semiconductor switch, and discharge via the other one, with the two switches uninterrupted. Each semiconductor switch is pref. formed by a triac (T1, 2) and a diode (D1, 2) in series. USE/ADVANTAGE - For household machines such as washing machine, drier, or dishwasher. Reliable contactor disconnection when fault occurs in one active element of semiconductor switch.