Signals & Electrical
Normally Closed (NC)
A contact that is closed when it is not being activated.
IN ONE SENTENCE
The circuit normally conducts and opens when the device operates.
In normal English
NC circuits are often useful where a broken wire should also appear as a loss of signal, although the complete safety design matters.
Why would I use it?
Use it where the required logic or fail-detection strategy calls for a closed resting circuit.
THINK OF IT LIKE…
A door that starts closed and opens when triggered.
Related terms
Normally Open, changeover contact, relay
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