Overload protection relay
ATEX | SIRIUS 3RU Siemens Safety

SIRIUS overload relays with screw-type, spring-loaded or ring cable lug connections reliably protect loads as well as other switching and protective devices in the respective load feeder against overload, phase imbalance and phase failure. Thanks to ATEX certification, they can be used in many different applications, even under the particularly harsh conditions of the process industry. The overload relays can easily be used with the contactors of the modular SIRIUS system.

There are two versions of overload relays: thermal and electronic.

In the main circuit, the SIRIUS 3RU thermal overload relays are responsible for current-dependent overload protection of electrical loads (e.g. motors). The 3RU2 overload relays are available with spring-loaded, screw-type and ring cable lug connections - for a particularly flexible implementation. In the 3RU2 overload relays, the power losses are 5 to 10 % lower than for the previous models thanks to a new bimetal technology. Therefore, the temperature within the control cabinet can be reduced as well.