Quiet mains switch with triac - has thermal switch and triac in parallel between supply and load and in thermal contact

摘要

The mains switch, for 220V and 16A max., is made to operate quietly by using a semiconductor switch in parallel with thermally triggered mechanical switch. The semiconductor eg a triac (1) is in thermal contact with the thermally triggered switch (3), with its make contacts (7, 8) normally open. The two switches are in parallel in the main current path. The mechanical thermal switch consists of a bimetal strip onto which the triac is mounted to ensure the necessary thermal contact.