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Siemens 3RU7146-4KB0 — Overload Relays

Siemens 3RU7146-4KB0 SIRIUS thermal overload relay, 75 A

MPN3RU7146-4KB0

Siemens SIRIUS 3RU7146-4KB0 thermal overload relay, S3 size, 75 A rated operational current, Class 10 trip class, screw terminals, IP20 front / IP00 terminal area.

Siemens 3RU7146-4KB0 datasheet (PDF)
Source DocumentedChannel stated on listing & quote
Condition PhotosReal unit photos / video on request
WhatsApp AnswersFast human replies for machine-down parts
Worldwide DispatchDHL/FedEx — transit quoted per order
Independent China distributor & sourcing agent· Listing updated Sep 2026

Specifications

3RU7146-4KB0 — Identification
ParameterValue
Product brand nameSIRIUS
Product designationThermal overload relay
Frame size (overload relay)S3
Combinable contactor sizesS3
3RU7146-4KB0 — Protection & Trip
ParameterValue
Overload current setting range57 ... 75 A
Trip classCLASS 10
Overload release typethermal
3RU7146-4KB0 — Electrical (main circuit)
ParameterValue
Rated operational current75 A
Poles (main circuit)3
Rated operating frequency50 ... 60 Hz
Rated insulation voltage (AC, pollution degree 3)1 000 V
Rated surge withstand voltage8 kV
Main current circuitscrew-type terminals
Power loss at rated current (hot)18.9 W
Per pole6.3 W
3RU7146-4KB0 — Auxiliary contacts
ParameterValue
Switching current at 24 V3 A
Switching current at 230 V2 A
3RU7146-4KB0 — Connection & Mounting
ParameterValue
Mounting / fastening methodContactor mounting
Mounting positionwith vertical mounting surface +/-135° rotatable, with vertical mounting surface +/- 45° tiltable to the front and back
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)
3RU7146-4KB0 — Environmental
ParameterValue
Operating temperature-20 ... +55 °C
Transport temperature-25 ... +70 °C
Relative humidity, operating0 ... 90 %
Max. installation altitude2 000 m
3RU7146-4KB0 — Mechanical
ParameterValue
Width70 mm
Height120 mm
Depth140 mm

Product details

What the 75 A and Class 10 mean for motor protection

The 3RU7146-4KB0 is a SIRIUS thermal overload relay rated 75 A operational current — that's the full-load motor current it's sized to protect, not a switching rating. It mounts directly onto a S3-size contactor via the contactor mounting fastening method, saving DIN rail space and keeping the power loop short. The relay is rated for AC/DC main circuits up to 1000 V at 50/60 Hz.

Main terminal torque is 4 to 6 N·m; auxiliary terminals are 0.8 to 1.2 N·m — over-torquing strips the threads on the smaller auxiliary screws. Side clearance to grounded parts is 6 mm minimum. The relay is IP20 on the front face but IP00 at the terminal area — the terminals are live-touch accessible, so the panel door or a terminal cover must provide the touch protection.

Frequently asked questions

What contactor does the 3RU7146-4KB0 mount on?

It mounts on S3-size SIRIUS contactors via the contactor mounting fastening method. The S3 size designation matches the company-specific contactor frame, so the relay clips directly onto the contactor without a separate base.

What is the IP rating on the 3RU7146-4KB0?

IP20 on the front face, IP00 at the terminals. The terminal area is not touch-protected — the panel door or a terminal shroud must provide the safety barrier.

MPN
3RU7146-4KB0