What is a heater in the context of motor protection?

In the context of motor protection, a heater refers to a short length of conductor designed with specific resistance that generates heat when an electrical current passes through it. This heating element is usually part of a thermal overload relay or device used for motor protection. When the motor operates, the current flowing through the heater creates a predictable amount of heat based on the resistance.

As the motor experiences overload conditions, it draws higher currents, leading to increased heat in the heater. When the heat reaches a predetermined threshold, it activates a mechanism to open the circuit and stop the motor, preventing damage from overheating. This crucial function helps protect the motor from prolonged overload conditions, thus ensuring safe and reliable operation.

In contrast, the other choices do not align with the definition of a heater in motor protection. A device that increases motor speed does not relate to protection but rather to performance. A temperature monitoring device is more associated with thermocouples or sensors, while a safety cut-off switch performs a different role by interrupting electrical flow but does not generate heat for overload protection. Understanding the specific function of the heater clarifies its vital role in maintaining motor safety and longevity.