What is the effect of a properly functioning motor overload relay?

• A. Increases motor efficiency
• B. Prevents motor overheating by opening the circuit
• C. Allows continuous operation without interruption
• D. Maximizes voltage to the motor

Answer: (B)

A properly functioning motor overload relay plays a crucial role in protecting electric motors from damage caused by overheating. When an electric motor operates under excessive load, it can draw more current than it is designed to handle, leading to increased temperature and potential burnout. The overload relay detects this excess current and responds by opening the circuit, which disconnects the power supply to the motor. This protective mechanism helps to prevent overheating and ensures that the motor does not suffer catastrophic failure.

In contrast, increasing motor efficiency or maximizing voltage to the motor would not directly relate to the primary purpose of an overload relay. Additionally, while continuous operation may be desirable in many scenarios, the primary function of an overload relay is safety and protection, not necessarily uninterrupted operation. Thus, the correct identification of the relay's role in preventing overheating addresses the essential function it fulfills in motor protection systems.