What is a Form B relay, and when should they be used?

Form B relays (or normally closed/NC relay) have a single set of contacts that are normally closed, meaning the circuit is closed when the relay is not energized. When the relay is energized, the contacts open, interrupting the current flow. Form B relays are frequently used to ensure that a circuit is normally closed and only opens when triggered. They are used for safety applications, such as emergency shutdowns or fault detection systems.

Read more about relays in our white paper: “Choosing the Correct Relay for Your Application“