Is NC Normally Open or Normally Closed?
2 Answers
NC stands for Normally Closed, which refers to a contact that remains in a closed and conductive state when not energized. A contact is an output form where the load current is not connected when the detection body is inactive. The working principle of a relay is: when the change in the input quantity meets the specified requirements, it causes a predetermined step change in the controlled quantity in the electrical output circuit. Relays are used in automated control circuits as automatic switches that use a small current to control the operation of a large current. Their functions in a circuit include: 1. Automatic adjustment; 2. Safety protection; 3. Circuit switching. They are categorized into normally open type, normally closed type, and changeover type.
In a vehicle's electrical system, NC refers to a normally closed contact, which is a point that remains closed under normal conditions, allowing current to flow freely. For example, in door locks or headlight relays, this design keeps the device connected when not activated, preventing accidental operation. If the NC contact malfunctions, such as due to corroded contacts or loose wiring, it may result in windows failing to roll up or lights not turning on, affecting daily use and safety. Compared to a normally open (NO) contact, which remains open and only closes when activated, the difference is significant. I recommend regular circuit maintenance to check plug and relay conditions; novice car owners can use a multimeter for simple testing—the resistance of an NC contact should be close to zero under normal conditions, otherwise, professional service is needed.
