SIRIUS 3RU Thermal Overload Relays

3RU Thermal overload relays up to 100 A have been designed to provide current-dependent protection for loads with normal starting against impermissibly high temperature rises due to overload, phase asymmetry or phase failure.
An overload or phase failure results in an increase of the motor current beyond the set rated motor current. Via heating elements, this current rise increasingly heats up the bimetal strips located inside the device. The deflection of these bimetal strips eventually activates the auxiliary contacts via a release mechanism. The contacts then disconnect the load via a contactor.
(Thecontactor function is not an integral component of the overload relay).