SIRIUS thermal overload relay for motor protection
The Siemens 3RU2126-4BB0-ZX95 is a SIRIUS thermal overload relay, size S0, designed for direct mounting onto a contactor to protect motors against overload and phase loss.
Auxiliary contact and tripped signal
The relay includes an integrated auxiliary switch with a dedicated 'Tripped' message contact — the note 'for message Tripped' means this variant has a separate signal contact that changes state when the relay trips, so a PLC or indicator can register the fault without wiring through the main contactor coil circuit.
Dimensions are 85 mm wide × 85 mm high × 45 mm deep — the S0 footprint is the smallest SIRIUS overload relay size, so it fits tightly on a contactor in a crowded DIN-rail enclosure. Mounting is direct onto the contactor via the fastening method 'contactor mounting' — no separate DIN-rail clip needed; the relay snaps onto the contactor and the power connections pass through.
Environmental range and compliance
RoHS compliance date is 10/01/2009 — the part meets the EU RoHS directive for restricted substances.