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Siemens 3RU2126-4NB0 — Overload Relays

Siemens 3RU2126-4NB0 SIRIUS Thermal Overload Relay, Class 10

MPN3RU2126-4NB0
Active

Siemens SIRIUS S0 thermal overload relay, 3RU2126-4NB0, Class 10 trip, 690 V rated, 85 mm depth, with integrated auxiliary switch for tripped indication.

$36.83Ref. price · indicative, final on quote
Siemens 3RU2126-4NB0 datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

3RU2126-4NB0 — Identification
ParameterValue
Product brand nameSIRIUS
Product designationthermal overload relay
Frame size (overload relay)S0
Combinable contactor sizesS0
Reference code (IEC 81346-2)F
3RU2126-4NB0 — Protection & Trip
ParameterValue
Overload current setting range23 ... 28 A
Trip classCLASS 10
Overload release typethermal
3RU2126-4NB0 — 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 value (AC-3e), max.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
3RU2126-4NB0 — Auxiliary contacts
ParameterValue
Auxiliary contacts: NO1
Auxiliary contacts: NC1
Auxiliary contacts: CO (changeover)0
Auxiliary switch short-circuit protection (required fuse)fuse gG: 6 A, quick: 10 A
Switching current at 24 V2 A
Switching current at 60 V0.3 A
Switching current at 110 V0.22 A
Switching current at 120 V3 A
Switching current at 125 V0.22 A
Switching current at 220 V0.11 A
Switching current at 230 V2 A
Switching current at 400 V1 A
3RU2126-4NB0 — Connection & Mounting
ParameterValue
Mounting / fastening methodContactor mounting
Mounting positionany
Main-circuit connector arrangementTop and bottom
Auxiliary/control circuit connection typescrew-type terminals
Removable aux./control terminalNo
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)
3RU2126-4NB0 — Environmental
ParameterValue
Operating temperature-40 ... +70 °C
Storage temperature-55 ... +80 °C
Transport temperature-55 ... +80 °C
Relative humidity, operating10 ... 95 %
Max. installation altitude2 000 m
3RU2126-4NB0 — Mechanical
ParameterValue
Width45 mm
Height85 mm
Depth85 mm

Product details

Field notes

The 3RU2126-4NB0: The integrated auxiliary switch outputs a 'Tripped' message for PLC or indicator, sharing the same screw terminals. Mounts directly onto the SIRIUS contactor via the built-in fastening method – no separate DIN rail bracket needed. The S0 frame keeps the panel footprint compact at 45 mm wide, 85 mm deep. Temperature compensation from -40 to +60 °C ensures stable trip performance across the panel environment; operational range extends to -40 to +70 °C. The screw terminals accept 2x (0.5 to 2.5 mm²) solid or stranded with a Pozidriv PZ2 bit.

Frequently asked questions

What is 3RU2126-4NB0's listed note (for message 'Tripped') on this component line?

The relay's integrated auxiliary switch signals a 'Tripped' status, which is indicated in the specs as the note field.

What is 3RU2126-4NB0's listed depth (85 mm) on this component line?

The depth is 85 mm, with a width of 45 mm and height of 85 mm, all specified in the datasheet.

What compliance documentation does this brand provide for 3RU2126-4NB0 (RoHS, REACH, UL, IEC)?

The datasheet records a substance prohibitance date of 10/01/2009, indicating RoHS/REACH compliance. The relay meets IEC thermal overload relay standards.

MPN
3RU2126-4NB0