What are NO and NC on the AC contactor?

On an AC contactor, NO stands for Normally Open and NC stands for Normally Closed. Here's a detailed explanation:

NO (Normally Open)

• Definition: A normally open contact is in an open state when the contactor coil is not energized. This means that there is no electrical connection or current flow through this contact in its normal, unpowered state.
• Function and Operation: When the coil of the AC contactor is energized, usually by applying an appropriate voltage, a magnetic field is generated. This magnetic field attracts the moving parts of the contactor, causing the normally open contact to close. Once closed, it allows current to flow through the contact, completing an electrical circuit. This is useful for various applications such as starting a motor or turning on a particular device when the contactor is activated.
• Example of Use: Suppose you have a motor starter circuit. The NO contact of the AC contactor can be wired in series with the motor's power supply. When the contactor coil is energized (for example, by a start button being pressed), the NO contact closes, allowing current to flow to the motor and start it running.

NC (Normally Closed)

• Definition: A normally closed contact is in a closed state when the contactor coil is not energized. In this state, current can flow through the contact, creating an electrical path.
• Function and Operation: When the coil of the AC contactor is energized and the magnetic field is produced, the normally closed contact is forced to open, breaking the electrical circuit. This interruption of the current flow can be used to perform specific functions in a circuit, such as stopping a motor when the contactor is activated or providing a safety interlock.
• Example of Use: In a motor control circuit, the NC contact of the AC contactor can be used in an interlocking arrangement. For example, it can be connected to a circuit that prevents another motor or device from operating simultaneously. When the contactor for one motor is energized and its NC contact opens, it can break the circuit for the other motor, ensuring that both motors do not run at the same time, which could cause overloading or other problems.