Momentary switch controls mains with latch-on and remote shutdown
The purpose of this Design Idea was to improve reliability, add new features, and replace a latching power switch with a momentary one.
The features are:
- The switch has foolproof protection against too frequent switching, which can be harmful for many applications.
- It can handle significant power because manual control and switching are separated.
- If an unexpected power outage occurs, the switch disconnects and remains off after power returns.
- A unit can switch itself off.
The control button BUT1 requires normally open and normally closed contacts, which must not be closed simultaneously.
Initially, while the button is not pressed, the switch is opened because relay K1 is deactivated. The normally-open contacts of the relay and the button are the only components under voltage in this state.
For more detail: Momentary switch controls mains with latch-on and remote shutdown