Nate Electrical Practice Exam

On a magnetic motor starter, what component opens and shuts off the motor if too much current is drawn?

1. Holding coil

2. Heater

3. Relay

4. Trip armature

The correct answer is: Trip armature

In a magnetic motor starter, the component responsible for opening and shutting off the motor when too much current is drawn is the trip armature. This mechanism is designed to respond to overcurrent conditions by mechanically disconnecting the starter contacts when the current exceeds a predetermined threshold. The trip armature operates by moving in response to the magnetic forces generated by the overload condition. When the current is too high, it causes the trip mechanism to engage and physically move the release lever, which opens the contacts that allow current to the motor. This action prevents damage to the motor and wiring by interrupting the electrical flow, ensuring safety and operational efficiency. Understanding the function of the trip armature is crucial because it serves as a protective feature of the magnetic starter, which is essential for maintaining equipment longevity and preventing hazards associated with electrical overloads. The other components, while important in the overall operation of the starter, do not perform this specific function of interrupting power due to overcurrent.