overload relay： essential protection for electric motors
Release time:2025-09-24 23:16:50
An overload relay is a crucial protective device commonly used in electrical motor control circuits. Its primary purpose is to safeguard electric motors from damage caused by prolonged overcurrent conditions, ensuring the longevity and reliability of the motor. Overload relays are designed to detect when the motor's current exceeds a preset safe limit, automatically interrupting the power supply to prevent motor failure. This simple yet effective protection is essential in various industrial, commercial, and residential applications where electric motors are used.
How Does an Overload Relay Work?
The basic principle behind an overload relay is to monitor the current flowing through the motor. When the current exceeds the motor's rated value, the relay intervenes and disconnects the circuit to avoid motor damage. Overload relays operate through two main types： thermal overload relays and electronic overload relays.
Thermal Overload Relays
Thermal overload relays use a heating element to detect overcurrent conditions. As the motor draws excessive current, the heating element becomes hot. This heat causes a bimetallic strip inside the relay to bend, eventually opening the contacts and breaking the circuit. Once the relay is triggered, it will remain open until the system is manually reset.
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