The Siemens SIRIUS 3RB series is a manual-automatic reset solid-state overload relay for inverse-time delayed protection of loads with normal and heavy starting against excessive temperature rises due to overload, phase unbalance or phase failure. It has a size S10 and S12. It can be mounted with any type mounting as contactor mounting or stand-alone installation. The type of electrical connection for main circuit is through bus bar connection and for auxiliary circuit is through screw-type terminal. Due to the wide current setting ranges and various tripping characteristics, complete series of motors are covered with just a few types. It has low heat loss which makes it energy-efficient and help to reduce the temperature rise in the control cabinet. Ambient operating temperature is -25 to +60 °C Operating frequency is 50 to 60 Hz Trip class is CLASS 10E