What is an overload relay and why is it used in motor circuits?

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Multiple Choice

What is an overload relay and why is it used in motor circuits?

Overload relays in motor circuits act as protective devices that watch the motor current. If the current rises above the motor’s rated full-load current for a period long enough to cause overheating, the relay trips and opens the circuit to the motor. This stops power to the motor and helps prevent damage to windings and insulation from overheating due to overload, stall, or blocked rotor conditions. They’re usually thermal (bimetal) or electronic and are wired so that tripping the relay also drops the motor out via the contactor. The current setting is adjustable to match the motor, and trips can be automatic after cooling or manually reset. They respond to sustained overloads rather than brief startup surges, providing protection without hindering normal operation.

Overload relays in motor circuits act as protective devices that watch the motor current. If the current rises above the motor’s rated full-load current for a period long enough to cause overheating, the relay trips and opens the circuit to the motor. This stops power to the motor and helps prevent damage to windings and insulation from overheating due to overload, stall, or blocked rotor conditions. They’re usually thermal (bimetal) or electronic and are wired so that tripping the relay also drops the motor out via the contactor. The current setting is adjustable to match the motor, and trips can be automatic after cooling or manually reset. They respond to sustained overloads rather than brief startup surges, providing protection without hindering normal operation.

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