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Siemens 3RU6126-1FB0 — Overload Relays

Siemens 3RU6126-1FB0 SIRIUS Overload Relay, 3.5–5 A, Class 1

MPN3RU6126-1FB0

Siemens SIRIUS, thermal overload relay, 3RU6126-1FB0, adjustable 3.5–5 A, Class 10, size S0, screw-type terminals, contactor mounting.

Siemens 3RU6126-1FB0 datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

3RU6126-1FB0 — Identification
ParameterValue
Product brand nameSIRIUS
Product designationThermal overload relay
Combinable contactor sizesS0
3RU6126-1FB0 — Protection & Trip
ParameterValue
Overload current setting range3.5 ... 5 A
Trip classCLASS 10
Overload release typethermal
3RU6126-1FB0 — Electrical (main circuit)
ParameterValue
Rated operational current5 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)6.6 W
Per pole2.2 W
3RU6126-1FB0 — Auxiliary contacts
ParameterValue
Switching current at 24 V2 A
Switching current at 110 V0.22 A
Switching current at 230 V2 A
3RU6126-1FB0 — Connection & Mounting
ParameterValue
Mounting / fastening methodContactor mounting
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)
Conductor range (AWG), main contacts2x (16 ... 12), 2x (14 ... 8)
Conductor range (AWG), auxiliary contacts2x (20 ... 16), 2x (18 ... 14)
3RU6126-1FB0 — Environmental
ParameterValue
Operating temperature-40 ... +70 °C
Transport temperature-55 ... +80 °C
Relative humidity, operating0 ... 90 %
Max. installation altitude2 000 m
3RU6126-1FB0 — Mechanical
ParameterValue
Width45 mm
Height85 mm
Depth85 mm

Product details

Motor protection relay, size S0, 3.5–5 A

It mounts directly onto a size S0 contactor, forming a compact motor starter package.

Integration with S0 contactors

Fastening method is contactor mounting — the relay snaps onto the S0 contactor without additional brackets. The screw-type 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. Tightening torque for main contacts is 2 to 2.5 N·m. The 85 mm depth and 45 mm width leave room for side-by-side spacing; Siemens requires 6 mm clearance to grounded parts at the side.

The relay withstands 8g shock at 11 ms per IEC 60068-2-27. The substance prohibitance date of 05/01/2012 confirms RoHS compliance since that date.

Frequently asked questions

How do I get current pricing and availability for 3RU6126-1FB0?

The 3RU6126-1FB0 is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time.

What is the adjustable current range on 3RU6126-1FB0?

The adjustable current response value is 3.5 to 5 A.

What contactor size does 3RU6126-1FB0 mount onto?

It mounts onto a size S0 contactor using the contactor mounting fastening method.

What compliance documentation does 3RU6126-1FB0 have?

The substance prohibitance date of 05/01/2012 confirms RoHS compliance since that date. Rated insulation voltage is 690 V at pollution degree 3, with a surge voltage resistance of 6 kV.

MPN
3RU6126-1FB0