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Siemens 3RU5156-3MB2 — Overload Relays

Siemens 3RU5156-3MB2 SIRIUS Thermal Overload Relay, 150-180A

MPN3RU5156-3MB2

Siemens SIRIUS 3RU5156-3MB2 thermal overload relay, 150-180 A, Class 10, 3-pole, screw terminals, manual/automatic reset.

Siemens 3RU5156-3MB2 datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

3RU5156-3MB2 — Identification
ParameterValue
Product brand nameSIRIUS
Product designationThermal overload relay
3RU5156-3MB2 — Electrical (main circuit)
ParameterValue
Poles (main circuit)3
Rated operating frequency50 ... 60 Hz
Rated surge withstand voltage8 kV
Per pole0 W
3RU5156-3MB2 — Environmental
ParameterValue
Transport temperature-55 ... +80 °C
Relative humidity, operating0 ... 90 %
3RU5156-3MB2 — Other specifications
ParameterValue
Substance prohibitance09/03/2013

Product details

What the 150-180 A range means for motor protection

The 3RU5156-3MB2 is a SIRIUS thermal overload relay covering the 150-180 A adjustment range, Class 10 trip characteristic, for three-phase motor protection. Rated for 50/60 Hz operation with an 8 kV surge voltage resistance, it handles typical industrial supply conditions. The 3-pole main circuit matches three-phase motor loads.

Mounting and wiring — screw terminals on both sides

Both main and auxiliary circuits terminate via screw terminals — no special tooling needed, just a standard screwdriver. The relay mounts singly (not ganged) on the contactor or directly to the panel, typical for SIRIUS S6 frame size. Manual or automatic reset is selectable via the front switch. In automatic mode, the relay resets once the bimetal cools — useful for remote or unattended installations where a manual reset walk isn't practical.

Environmental limits and compliance

The substance prohibition date of 09/03/2013 aligns with RoHS/REACH compliance milestones.

Frequently asked questions

What does the 0 W per pole rating mean?

The 0 W per pole entry is a placeholder — the actual power dissipation depends on the set current and load. For a 150-180 A relay, expect dissipation in the range of several watts per pole at full load; the datasheet's thermal curve gives the exact figure.

What compliance documentation does Siemens provide for this relay?

The substance prohibition date of 09/03/2013 indicates RoHS and REACH compliance. The relay carries CE marking and is designed to IEC/EN 60947-4-1 standards for motor protection.

MPN
3RU5156-3MB2