Question

The overload protector provides protection against the _________.

• A. extreme compression ratio
• B. freezing up of the evaporator
• C. leak of air into the system
• D. overheating and burn out of motor winding

Hint:

Overload means excess current, which heats the motor winding. The protector cuts the supply to save the winding.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
A hermetic or semi-hermetic compressor motor needs protection from too much current and heat. The overload protector is a safety device fitted for this.

Step 2: Key Approach:
The overload protector senses the motor current and temperature. When either becomes too high, it opens the circuit and stops the motor.

Step 3: Detailed Explanation:
High current can flow when the motor starts under load, when the voltage is low, or when the compressor is stuck.
This current heats the motor winding. A bimetallic strip inside the protector bends when it gets hot and breaks the circuit.
So the winding is saved from overheating and burning out.

Step 4: Why the other options are wrong.
Extreme compression ratio is controlled by pressure cutouts (high and low pressure controls).
Freezing up of the evaporator is controlled by the thermostat or defrost control.
Leak of air into the system is not guarded by an overload protector. It is avoided by proper evacuation and leak testing.

Final Answer:
The overload protector guards against overheating and burn out of the motor winding. This is option (D).