What is NO and NC?

NO (Normally Open) and NC (Normally Closed) are basic contactor types used in electrical circuits. These are terms that describe whether the contacts are open or closed in their normal state.

+ NO (Normally Open): NO is a contact type that is normally open. This means that when a circuit is closed, the contact is open. NO contacts are used to open a circuit when closed.

+ NC (Normally Closed): NC is a contact type that is normally closed. This means that when a circuit is closed, the contact is closed. NC contacts are used to close a circuit when closed.

These contact types are also used to describe the output type of sensors, such as inductive sensors. For example, a PNP NC inductive sensor has a normally closed output, and it opens its output when a metal object is detected. An NPN NO inductive sensor, on the other hand, has a normally open output, and it closes its output when a metal object is detected.

In summary, which contact type is more advantageous depends on your application requirements. NC output sensors are advantageous from a safety perspective because they open the circuit if the sensor cable breaks or there is a fault. NO output sensors are more advantageous when a metal object needs to be removed from the circuit. These contact types are used in a variety of electrical devices, such as sensors, relays, switches, and contactors.