Overload Relays

Overload Relays for reliable motor protection

IPD offers a complete range of overload relays designed for industrial electric motors in motor control systems. Our portfolio includes both thermal overload relays for temperature-based protection and electronic overload relays for accurate, adjustable trip settings. These devices safeguard motors from sustained overcurrent conditions, reducing downtime and preventing damage. Designed to integrate seamlessly with contactors and other motor control components, the range of overload relays are suitable for a variety of motor applications, from manufacturing to process control.

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Overload Relays - FAQs

What is a motor overload relay and how does it work?

A motor overload relay is a motor protection device that trips a circuit when the motor draws current above its rated load for a sustained period. In thermal types, a bimetal strip bends with heat, opening the circuit. In electronic overload relays, current sensors measure load and activate a trip signal when overload conditions are detected. Both types prevent motor damage from overheating.

What is a 3-phase overload relay used for?

A 3-phase overload relay protects three-phase electric motors from sustained overloads, phase loss, and unbalanced currents. It continuously monitors all three phases and trips the motor circuit when abnormal conditions are detected. This type is standard in motor control panels for industrial machinery.

How do I set overload relay parameters for motor protection?

Overload relay settings must match the motor’s full load current rating, as specified on the motor nameplate. The adjustment dial or programming interface is set to trip just above this current, allowing for normal start-up surges while protecting against sustained overloads. Incorrect settings can lead to nuisance tripping or motor damage.

Please note: The relay remains inactive at currents up to 1.05 x I setting current, but will operate in a definite-trip mode once the current reaches 1.2 x I setting current.

How do overload relays integrate into motor control panels?

Overload relays are typically mounted with contactors in motor starters within a motor control panel. They form part of the overload protection device chain, ensuring safe motor shutdown during overloads without damaging upstream switchgear.