What is Normally Closed?

Definition

A switch or relay contact that is closed (conducting) in its default unpowered state and opens when activated. Normally closed contacts are used in safety circuits so that a broken wire or lost power triggers protective shutdown.

Related Terms

Normally Open

A switch or relay contact that is open (non-conducting) in its default unpowered...

Emergency Stop

A safety function that immediately halts all machine motion when activated, typi...

Safety Relay

A relay module with redundant contacts and monitoring circuits designed for safe...

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