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Siemens 3RU2126-4CB0 — Overload Relays

Siemens 3RU2126-4CB0 SIRIUS Overload Relay, CLASS 10

MPN3RU2126-4CB0
Active

Siemens SIRIUS thermal overload relay, 3RU2126-4CB0, CLASS 10, rated 690 V, S0 frame, screw terminals, for contactor mounting.

$117.75Ref. price · indicative, final on quote
Siemens 3RU2126-4CB0 datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

3RU2126-4CB0 — Identification
ParameterValue
Product brand nameSIRIUS
Product designationthermal overload relay
Frame size (overload relay)S0
Combinable contactor sizesS0
Reference code (IEC 81346-2)F
3RU2126-4CB0 — Protection & Trip
ParameterValue
Overload current setting range17 ... 22 A
Trip classCLASS 10
Overload release typethermal
3RU2126-4CB0 — Electrical (main circuit)
ParameterValue
Rated operational current22 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)8.1 W
Per pole2.7 W
3RU2126-4CB0 — 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
3RU2126-4CB0 — 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)
3RU2126-4CB0 — 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
3RU2126-4CB0 — Mechanical
ParameterValue
Width45 mm
Height85 mm
Depth85 mm

Product details

The Siemens 3RU2126-4CB0 is a SIRIUS thermal overload relay with CLASS 10 trip protection, rated for 690 V and mounted directly on a contactor. CLASS 10 trip class. S0 frame size. Screw terminals accept 2x 0.5…1.5 mm² solid or 2x 0.75…2.5 mm² stranded. Torque with PZ2 bit. Mount in any position; the relay fastens to the contactor via M4 screws.

The built-in auxiliary switch signals a tripped condition — the part carries a 'Note for message Tripped' in its documentation, so you get a positive indication on fault. Ambient operating range -40…+70°C with temperature compensation active to +60°C. Storage and transport hold -55…+80°C. Fits standard 45 mm DIN space when coupled to the contactor.

Substance prohibitance date 10/01/2009.

Frequently asked questions

What does the 'Note for message Tripped' mean?

The relay includes an integrated auxiliary switch that provides a tripped indication signal.

What is the depth of this overload relay?

85 mm depth, with 45 mm width and 85 mm height.

What compliance documentation is available?

A substance prohibitance date of 10/01/2009 is listed. For specific RoHS, REACH, or UL declarations, request via RFQ.

MPN
3RU2126-4CB0