What happens to the control circuit in a magnetic motor starter when the melting alloy overload activates?

• A. It continues to provide power to the motor
• B. It opens to de-energize the coil
• C. It becomes a closed circuit
• D. It bypasses the overload protection

Answer: (B)

When the melting alloy overload activates, the control circuit in a magnetic motor starter opens to de-energize the coil. This occurs because the melting alloy is designed to respond to excessive current by melting and breaking the circuit connection. As the alloy melts, it effectively disconnects the control circuit, which in turn de-energizes the coil that operates the magnetic contactor. This action stops the power supplied to the motor, thus protecting it from damage caused by overheating or excessive current draw.

Understanding this mechanism is crucial for ensuring that electric motors operate safely and efficiently, preventing damage or failure due to overload conditions.