Siemens AG 3RU1146-4HBO Sirius Overload Relay

Siemens Sirius 3RU1146-4HBO overload relay is a size S3 thermal overload relay for motor protection, designed to mount directly on a compatible Sirius contactor in a three‑phase system. It provides screw-terminal connections for the main circuit and for the auxiliary circuit, and it includes 1 normally open plus 1 normally closed auxiliary contact with a manual-automatic reset option for field servicing. This device is part of the Sirius 3RU1146 family, with suffix-dependent current ratings; for example EB0 variants cover roughly 22–32 A and JB0 variants about 45–63 A, while LD0 configurations reach 70–90 A in other versions, so verify the exact rating for the 4HBO model from the supplier. The relay is intended to cut power to a motor when overheating is detected, aligning with Siemens’ standard motor protection approach and enabling reliable integration with Siemens control gear.