What is the role of a thermal overload relay?

The role of a thermal overload relay is to prevent motor overheating by monitoring the temperature of the motor or the current flowing through it. When a motor experiences excessive heat due to prolonged overload conditions, the thermal overload relay activates to open the circuit, thereby disconnecting power to the motor to prevent potential damage from overheating. This is crucial for protecting both the motor and the overall electrical system, ensuring longevity and reliability of the equipment.

In the context of electrical systems, thermal overload relays are essential because motors can draw excessive current under various conditions, which can generate heat. If this heat is allowed to build up without any form of control, it can lead to insulation failure and ultimately motor burnout. Hence, the primary function of a thermal overload relay is vital for the safe operation of motors in various applications.

The other options focus on different functions that are not within the scope of a thermal overload relay. For example, measuring energy consumption pertains to devices like energy meters, while short circuit protection is usually handled by circuit breakers or fuses. Signaling voltage spikes relates to surge protectors or transient voltage surge suppressors, which are designed to manage unexpected voltage increases rather than controlling overheating. Thus, option C correctly identifies the specific protective role of a thermal overload relay in