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Siemens 3RU6126-4NB1 — Overload Relays

Siemens 3RU6126-4NB1 SIRIUS Overload Relay, 23-28 A, Class 1

MPN3RU6126-4NB1

Siemens SIRIUS 3RU6126-4NB1 thermal overload relay, 23-28 A adjustable, Class 10, size S0, screw-type terminals, stand-alone installation.

Siemens 3RU6126-4NB1 datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

3RU6126-4NB1 — Identification
ParameterValue
Product brand nameSIRIUS
Product designationThermal overload relay
Combinable contactor sizesS0
3RU6126-4NB1 — Protection & Trip
ParameterValue
Overload current setting range23 ... 28 A
Trip classCLASS 10
Overload release typethermal
3RU6126-4NB1 — Electrical (main circuit)
ParameterValue
Rated operational current28 A
Poles (main circuit)3
Rated operating frequency50 ... 60 Hz
Rated insulation voltage (AC, pollution degree 3)690 V
Rated surge withstand voltage6 kV
Main current circuitscrew-type terminals
Power loss at rated current (hot)9.6 W
Per pole3.2 W
3RU6126-4NB1 — Auxiliary contacts
ParameterValue
Switching current at 24 V2 A
Switching current at 110 V0.22 A
Switching current at 230 V2 A
3RU6126-4NB1 — Connection & Mounting
ParameterValue
Mounting / fastening methodstand-alone installation
Mounting positionany
Main-circuit connector arrangementTop and bottom
Auxiliary/control circuit connection typescrew-type terminals
Conductor cross-section: solid or stranded2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²)
Conductor cross-section: finely stranded with ferrule2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²)
3RU6126-4NB1 — Environmental
ParameterValue
Operating temperature-40 ... +70 °C
Transport temperature-55 ... +80 °C
Relative humidity, operating0 ... 90 %
Max. installation altitude2 000 m
3RU6126-4NB1 — Mechanical
ParameterValue
Width45 mm
Height97 mm
Depth95 mm

Product details

Integrator note — SIRIUS 3RU6126-4NB1

The Siemens 3RU6126-4NB1 is a SIRIUS thermal overload relay sized for motor protection in the 23-28 A adjustable range, Class 10 trip curve. It mounts stand-alone on the panel or directly onto an S0-frame contactor. Screw terminals on both main and auxiliary circuits accept 2x (0.5-1.5 mm²) solid or stranded, or 2x (0.75-2.5 mm²) with ferrules.

The adjustable current range of 23-28 A sets the motor full-load current (FLC) the relay protects.

Deployment context

Mounts in any position in the control panel. The stand-alone installation method means it can be DIN-rail mounted or screw-fixed directly to a backplate. The manual/automatic reset selector gives the commissioning engineer flexibility for remote restart or local intervention after a trip.

Frequently asked questions

What contactor frame does this relay combine with?

It is designed to combine with S0-frame contactors from the SIRIUS family, such as the 3RT102 or 3RT602 series.

What are the key ratings for fit verification?

Adjustable current range 23-28 A, Class 10 trip, rated operating voltage 690 V, 50/60 Hz, 3 poles. Screw terminals for main and auxiliary circuits.

What compliance documentation is available?

The part carries a substance prohibitance date of 05/01/2012, indicating RoHS/REACH compliance. The SIRIUS series typically provides UL, CSA, and CE certifications; verify specific approvals with the order code.

MPN
3RU6126-4NB1