Slow Make-Slow Break:

Purposely designed switch mechanism (“see–saw” type) with relatively slow operation to provide a slight time delay, permitting the ac wave to go through its zero-energy level (natural current zero duration is 8.35 msec).

Normally Open:

A term used to describe contacts which interrupt the circuit when in their normal position.


Printed circuit board.


A wall or housing that surrounds a switch, button or toggle to protect the switch from accidental operation.

Motor Load:

A switch load that simulates an electric motor, it usually specifies an in-rush current seven times the running current.