Overload protection relays are essential components in electrical systems, playing a critical role in safeguarding electrical equipment and ensuring the safety and reliability of industrial and residential power systems. These relays are designed to prevent overheating and subsequent damage to electrical machinery caused by excessive current flow. By detecting abnormal conditions such as overloads, they act as protective devices to cut off power when needed, thus preventing costly repairs and minimizing risks.

What is an Overload Protection Relay? An overload protection relay is an electrical device that monitors the current flowing through a circuit. If the current exceeds a predetermined threshold for a specific period, the relay activates and opens the circuit to protect the equipment. Typically, overload protection relays are used in conjunction with circuit breakers, fuses, or other protective devices in motors, transformers, and other electrical systems. The relay can be adjusted according to the system’s requirements, offering customized protection. Overload protection relays operate based on various principles, including thermal, magnetic, and electronic mechanisms. The thermal overload relay, one of the most commonly used types, utilizes a bimetallic strip that bends when it heats up due to excessive current. As the strip bends, it triggers the relay to trip and disconnect the power supply. Magnetic overload relays, on the other hand, use an electromagnet to trip the circuit when the current exceeds a set limit.