220V switch control circuit

tangwei8802429

220V switch control circuit [Copy link]

What are the functions of C2 and R11? What will be the impact if they are removed?

maychang

What are the functions of C2 and R11?

Reduces sparking when relay contacts switch.

tangwei8802429

maychang posted on 2022-2-12 07:57 "What are the functions of C2 and R11?" Reduce the sparks that occur when the relay contacts are switched.

Teacher, how does it work?

maychang

tangwei8802429 posted on 2022-2-12 08:33 How does it work?

Generally speaking, the loads controlled by industrial frequency switches are all inductive. We know that when the current passing through an inductor changes, an induced electromotive force will be generated, and the faster the current changes, the greater the induced electromotive force. Switch control can be said to be a process in which the current changes very, very quickly, so the induced electromotive force in the inductor is also high. When the contact is turned on and off, the induced electromotive force of the inductor acts on both ends of the contact, and sparks will be generated between the contacts.

After adding the capacitor, the speed of current change is slowed down, the induced electromotive force of the inductive load becomes smaller, and the spark when the contacts are opened will also be reduced.

maychang

tangwei8802429 posted on 2022-2-12 08:33 How does it work?

A small resistor is connected in series to prevent excessive current from discharging from the capacitor through the contacts when the contacts are opened and closed.