Panel Seal:

Sealed against the panel by way of o-ring or sealing washer preventing the ingress of dirt, dust or moisture based on the IP rating stated.

Sliding Contact:

Contacts that make or interrupt current flow by means of tangential motion (rotary, slip ring).

Normally Closed:

A term used to describe contacts which establish a circuit when in the normal position.

Passive Components:

Components which have no gain characteristics, such as capacitors and resistors.