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Siemens 3RU1126-4CB1 — Overload Relays

Siemens 3RU1126-4CB1 SIRIUS Thermal Overload Relay, Class 10

MPN3RU1126-4CB1

Siemens SIRIUS thermal overload relay, 3RU1126-4CB1, S0 frame, Class 10 trip, screw-type terminals, IP20 front, 690 V max AC-3.

Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Jul 2026

Specifications

3RU1126-4CB1 — Identification
ParameterValue
Product brand nameSIRIUS
Product designationthermal overload relay
Frame size (overload relay)S0
Combinable contactor sizesS0
3RU1126-4CB1 — Protection & Trip
ParameterValue
Trip classCLASS 10
3RU1126-4CB1 — Electrical (main circuit)
ParameterValue
Poles (main circuit)3
Rated insulation voltage (AC, pollution degree 3)690 V
Rated surge withstand voltage6 kV
Main current circuitscrew-type terminals
3RU1126-4CB1 — Auxiliary contacts
ParameterValue
Auxiliary contacts: NO1
Auxiliary contacts: NC1
Auxiliary switch short-circuit protection (required fuse)fuse gL/gG: 6 A, quick: 10 A
Switching current at 24 V1 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
3RU1126-4CB1 — Connection & Mounting
ParameterValue
Mounting positionwith vertical mounting surface +/-135° rotatable, with vertical mounting surface +/- 45° tiltable to the front and back
Conductor cross-section: solid2x (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)
3RU1126-4CB1 — Environmental
ParameterValue
Operating temperature-20 ... +70 °C
Storage temperature-55 ... +80 °C
Transport temperature-55 ... +80 °C
Relative humidity, operating100 %
Shock resistance8g / 10 ms
3RU1126-4CB1 — Mechanical
ParameterValue
Width45 mm
Height97 mm
Depth96 mm
3RU1126-4CB1 — Specifications
ParameterValue
Type Of ProtectionDMT 98 ATEX G 001

Product details

The Siemens 3RU1126-4CB1 is a SIRIUS-brand thermal overload relay in the S0 frame size, designed to protect motors against sustained overloads and phase-loss conditions by monitoring current and tripping a contactor's control circuit when the thermal model exceeds the setpoint. Rated for AC-3 switching duty up to 690 V, this relay mounts standalone or in combination with a matching S0 contactor; the IP20 front cover keeps live terminals finger-safe inside the panel.

Mounts on a vertical surface with ±135° rotation and ±45° tilt front/back — flexible for tight enclosures. Stand-alone installation is the default; side clearance of 6 mm is needed for heat dissipation. Main circuit terminals are screw-type, accepting 1x (16…12) or 1x (14…8) AWG. Auxiliary/control wiring uses 2x (0.5…1.5 mm²) or 2x (0.75…2.5 mm²) solid or finely stranded with ferrule. At 8.1 W total heat dissipation (2.7 W per pole) in hot AC operation, the S0 frame sheds heat through natural convection — derate if stacking multiple relays without spacing.

Operates from -20 to +70 °C, stores and transports from -55 to +80 °C. Withstands 8g shocks over 10 ms and 100 % relative humidity — suited for washdown-adjacent environments inside a sealed panel. Carries ATEX protection type DMT 98 ATEX G 001 for use in potentially explosive atmospheres when properly installed per the directive.

Frequently asked questions

What is the current rating of 3RU1126-4CB1?

The 3RU1126-4CB1 is a thermal overload relay; its trip current is set by the user within the relay's adjustment range. The relay's auxiliary contacts are rated at 1 A at 24 V, 3 A at 120 V, 2 A at 230 V, and 1 A at 400 V. The main circuit is rated for AC-3 duty up to 690 V.

Where can I buy 3RU1126-4CB1?

The 3RU1126-4CB1 is sourced to order against an RFQ through independent distribution channels. Submit a request for quote to confirm current availability and pricing — stock positions change daily.

How to wire a 3RU1126-4CB1 overload relay?

Main circuit terminals accept 1x (16…12) or 1x (14…8) AWG screw-type connections. Control/auxiliary wiring uses 2x (0.5…1.5 mm²) or 2x (0.75…2.5 mm²) solid or finely stranded with ferrule. The relay has no built-in auxiliary contacts — external auxiliaries must be added if needed.

What is the difference between 3RU1126-4CB1 and 3RU2126-4CB1?

Both are SIRIUS S0-frame thermal overload relays with Class 10 trip and the same mounting footprint. The 3RU2126-4CB1 typically covers a higher current setting range — verify the specific adjustment window on the nameplate against your motor FLA before substituting.

MPN
3RU1126-4CB1