Magnetic Overload Relay

Magnetic Overload Relay is What?

A Magnetic Overload Relay is a type of electrical protection device designed to protect motors and circuits from overcurrent (Overcurrent) by utilizing the principle of electromagnetic fields to trip the circuit. This makes magnetic overload relays suitable for protecting against short circuits and abnormally high starting currents.

How Magnetic Overload Relay Works

A Magnetic Overload Relay operates using a coil through which the motor's current flows, creating an electromagnetic field. When current passes through the coil, it generates a magnetic field. If the current exceeds the set value, the magnetic force is strong enough to pull the iron core (Plunger or Armature) and trip the contact to cut off the control circuit (Control Circuit), causing the Magnetic Contactor to stop supplying power to the motor.

Types of Magnetic Overload Relay

• Instantaneous (Immediate Action): Cuts the circuit immediately when current exceeds the set value, commonly used for short-circuit protection.
• Time Delay / Dashpot (Delayed Action): Uses oil or a plunger (Dashpot) to slow down the movement of the iron core so that it does not trip too quickly during motor startup (when current is temporarily high).