Which device is specifically designed to protect a motor from overload conditions?

Which device is specifically designed to protect a motor from overload conditions?

• A. Overload relay
• B. PLC input
• C. Timer relay
• D. Sensor

Answer: (A)

Protecting a motor from overload requires a device that responds to excessive current or heat and interrupts power to the motor. An overload relay is built for this purpose. It monitors motor current (and often motor temperature through a thermal element) and trips the circuit when the value exceeds a preset limit. By wiring in series with the motor contactor coil, it automatically opens the contactor to cut power and prevent winding damage. Many overload relays come in thermal or electronic forms and can be reset after the fault is cleared. Other options don’t provide this protective function by themselves. A PLC input is just a signal coming into the programmable logic controller; it doesn’t protect the motor. A timer relay introduces a delay in control actions but does not react to current or temperature to protect the motor. A sensor detects a physical condition but isn’t designed to stop motor power in an overload scenario.

Protecting a motor from overload requires a device that responds to excessive current or heat and interrupts power to the motor. An overload relay is built for this purpose. It monitors motor current (and often motor temperature through a thermal element) and trips the circuit when the value exceeds a preset limit. By wiring in series with the motor contactor coil, it automatically opens the contactor to cut power and prevent winding damage. Many overload relays come in thermal or electronic forms and can be reset after the fault is cleared.

Other options don’t provide this protective function by themselves. A PLC input is just a signal coming into the programmable logic controller; it doesn’t protect the motor. A timer relay introduces a delay in control actions but does not react to current or temperature to protect the motor. A sensor detects a physical condition but isn’t designed to stop motor power in an overload scenario.