Motor protection relay for the SIRIUS line
The 3RU5166-5FB1: It mounts directly under a contactor or as a standalone unit, with screw terminals on both the main and auxiliary circuits. The adjustable current response range is 1.8 to 2.5 A, with a rated operational current of 2.5 A, making it suitable for smaller motor loads that need Class 10 trip protection against sustained overcurrent. It operates on 50 to 60 Hz supply and withstands surge voltages up to 8 kV, giving it solid noise immunity in industrial environments with switching transients.
Class 10 trip curve and what it means for your motor
The 3-pole design covers all three phases, and the adjustable dial lets you fine-tune the trip point to match the motor nameplate FLA. Set it at the motor's full-load amps, not the relay's maximum rating. Ambient compensation is built into the SIRIUS 3RU5 series, so the trip characteristic stays consistent whether the panel runs at 25 °C or 55 °C — no manual derating needed for normal enclosure temperatures.
The 3RU5166-5FB1 is stocked in the independent distribution channel and can be quoted to order against your BOM quantity. RoHS compliance is covered by the substance prohibitance date of 09/03/2013, meaning the relay meets the EU RoHS directive for materials restriction.