Overload Relays

An overload relay protects a motor from burning out when it draws too much current for too long because of a jammed load, a lost phase or a failing bearing. Paired with a contactor, it forms a motor starter that trips before heat damages the windings.

Overload Relay Types

• Thermal (bimetallic) overload relays – simple, proven protection for standard motors
• Electronic overload relays – wide adjustment ranges, phase-loss detection and tighter accuracy
• Solid-state relays with communication – motor diagnostics over industrial networks
• Class 10, 20 and 30 trip curves – matched to standard and high-inertia starting loads
• Accessories – reset buttons, mounting adapters and auxiliary contacts

Sizing an Overload

Set the overload to the motor's full-load amps from its nameplate and select a trip class that allows normal starting time. Make sure the relay is compatible with your contactor brand and frame size. Electronic relays are a good upgrade when motors run in hot panels or need ground-fault and phase-imbalance protection.

Centro carries overload relays that pair with popular IEC and NEMA contactors, and our team can help you select the right overload for your motor and contactor.

Related categories: Motor Control | Line Reactors and Output Filters | Variable Frequency Drives | Configured Drives / Control Systems