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Siemens 3RU2126-4EJ0 — Overload Relays

Siemens 3RU2126-4EJ0 SIRIUS Thermal Overload Relay, Class 10

MPN3RU2126-4EJ0

Siemens SIRIUS, thermal overload relay, 3RU2126-4EJ0, size S0, Class 10, 32 A at 480/600 V, contactor mounting.

Source DocumentedChannel stated on listing & quote
Condition PhotosReal unit photos / video on request
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Worldwide DispatchDHL/FedEx — transit quoted per order
Independent China distributor & sourcing agent· Listing updated Sep 2026

Specifications

3RU2126-4EJ0 — Identification
ParameterValue
Product brand nameSIRIUS
Product designationthermal overload relay
Frame size (overload relay)S0
Combinable contactor sizesS0
Reference code (IEC 81346-2)F
3RU2126-4EJ0 — Protection & Trip
ParameterValue
Overload current setting range27 ... 32 A
Trip classCLASS 10
Overload release typethermal
3RU2126-4EJ0 — Electrical (main circuit)
ParameterValue
Rated operational current32 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 circuitRing cable lug connection
Power loss at rated current (hot)9.6 W
Per pole3.2 W
3RU2126-4EJ0 — 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
3RU2126-4EJ0 — Connection & Mounting
ParameterValue
Mounting / fastening methodContactor mounting
Mounting positionany
Main-circuit connector arrangementTop and bottom
Auxiliary/control circuit connection typering terminal lug connection
Removable aux./control terminalNo
3RU2126-4EJ0 — 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
3RU2126-4EJ0 — Mechanical
ParameterValue
Width45 mm
Height85 mm
Depth85 mm

Product details

It's designed to bolt directly onto a matching contactor, saving DIN-rail space and keeping the motor branch circuit compact. At 480 V or 600 V it carries a full-load motor current of 32 A, which corresponds to 15 kW at 400 V and 18.5 kW at 500 V — a common range for small-to-medium fixed-speed pumps, fans, and compressors.

That's the standard for standard motors with normal starting times — a pump that spins up in a couple seconds is fine; a high-inertia fan that takes 15 seconds to accelerate will nuisance-trip on a Class 10. If you've got a long-start load, you'd need a Class 20 or 30 relay instead. The 32 A rating at 480 V and 600 V tells you the heater element is sized for that full-load current point. The relay accepts a range of current settings below that maximum, so you dial it to the motor nameplate FLA. The 15 kW / 18.5 kW / 30 kW power ratings at 400 V, 500 V, and 690 V respectively are the motor power the relay can protect at those line voltages — match the motor's rated voltage and power, not just the current. The auxiliary contact is integrated — no separate add-on block needed for the trip-indication or status feedback to the PLC. The Note 'for message Tripped' on the nameplate means the relay has a visual flag and a separate N/C contact that opens when the bimetals trip, so the control system sees the fault even if the contactor coil drops out.

It mounts directly onto the contactor via the Fastening Method 'Contactor mounting', so no DIN rail bracket is needed underneath; the whole assembly clips onto the rail as one unit. The main circuit connection uses ring cable lugs, with M4 screw terminals sized for a Pozidriv PZ2 bit. Temperature compensation is active from -40 to +60 °C, so the trip curve stays accurate in a hot panel or a cold enclosure. The 3.2 W dissipation per pole at full load adds up — three poles at 9.6 W total — so if you're packing multiple contactor/relay pairs in a sealed cabinet, factor that heat into the ventilation calc.

Frequently asked questions

What is the note 'for message Tripped' on the 3RU2126-4EJ0?

That note indicates the relay has a built-in trip-indicator flag and a separate auxiliary contact (N/C) that opens when the bimetals trip. It provides a discrete signal — a 'message Tripped' — back to the control system, separate from the contactor coil circuit.

What is the depth of the 3RU2126-4EJ0?

The depth is 85 mm. The overall dimensions are 45 mm wide, 85 mm high, and 85 mm deep — size S0 frame.

What compliance documentation does Siemens provide for the 3RU2126-4EJ0?

The evidence records a Substance Prohibitance date of 10/01/2009, indicating RoHS compliance from that date. The SIRIUS family typically carries CE, UL, CSA, and IEC certifications. For specific documentation (declaration of conformity, UL file number), request it with your RFQ.

MPN
3RU2126-4EJ0