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Siemens 3RB2123-4PD0 — Overload Relays

Siemens 3RB2123-4PD0 SIRIUS Solid-State Overload Relay, Adju

MPN3RB2123-4PD0

Siemens SIRIUS solid-state overload relay, 3RB2123-4PD0, adjustable trip class 5E/10E/20E/30E, contactor-mount, ATEX Ex II (2) GD, 3-pole, screw-type main terminals, spring-loaded auxiliary terminals.

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

Specifications

3RB2123-4PD0 — Identification
ParameterValue
Product brand nameSIRIUS
Product designationsolid-state overload relay
Combinable contactor sizesS0
Reference code (IEC 81346-2)F
3RB2123-4PD0 — Protection & Trip
ParameterValue
Overload current setting range1 ... 4 A
Trip classCLASS 5E, 10E, 20E and 30E adjustable
3RB2123-4PD0 — 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
Power loss at rated current (hot)0.05 W
Per pole0.02 W
3RB2123-4PD0 — Auxiliary contacts
ParameterValue
Auxiliary contacts: NO1
Auxiliary contacts: NC1
Auxiliary contacts: CO (changeover)0
Auxiliary switch short-circuit protection (required fuse)fuse gL/gG: 6 A
Switching current at 24 V2 A
Switching current at 60 V0.55 A
Switching current at 110 V0.3 A
Switching current at 120 V4 A
Switching current at 125 V0.3 A
Switching current at 220 V0.11 A
Switching current at 230 V3 A
3RB2123-4PD0 — Connection & Mounting
ParameterValue
Mounting / fastening methodContactor mounting
Mounting positionany
Auxiliary/control circuit connection typespring-loaded terminals
Removable aux./control terminalYes
Conductor cross-section: solid2x (0.25 ... 1.5 mm²)
Conductor cross-section: finely stranded with ferrule2x (0.25 ... 1.5 mm²)
Conductor range (AWG), main contacts2x (14 ... 10)
Conductor range (AWG), auxiliary contacts2x (24 ... 16)
3RB2123-4PD0 — Environmental
ParameterValue
Operating temperature-25 ... +60 °C
Storage temperature-40 ... +80 °C
Transport temperature-40 ... +80 °C
Relative humidity, operating100 %
Max. installation altitude2 000 m
Shock resistance15g / 11 ms
3RB2123-4PD0 — Mechanical
ParameterValue
Width45 mm
Height73 mm
Depth75 mm
3RB2123-4PD0 — Specifications
ParameterValue
Type Of ProtectionPTB 06 ATEX 3001 Ex II (2) GD

Product details

Solid-state overload relay with adjustable trip class

The Siemens 3RB2123-4PD0 is a SIRIUS solid-state overload relay for three-phase motor protection. Trip class is field-adjustable among CLASS 5E, 10E, 20E, and 30E — so you match the thermal curve to the motor start profile: fast for submersible pumps, slow for high-inertia fans. Mounts directly to a contactor (fastening method: contactor mounting), saving panel width compared to a separate base.

ATEX and environmental ratings

ATEX certification PTB 06 ATEX 3001 Ex II (2) GD. Operating temperature range -25 to +60 °C, storage/transport -40 to +80 °C, 100 % relative humidity during operation. Shock resistance 15g / 11 ms; mounting position any.

Main current circuit uses screw-type terminals accepting 2x (0.25... 1.5 mm²) solid or 2x (14... 10) AWG. Auxiliary and control circuit uses spring-loaded terminals for faster wiring — 2x (0.25... 1.5 mm²) finely stranded with ferrule, or 2x (24... 16) AWG. Surge voltage resistance rated 6 kV; burst immunity 2 kV on power ports, 1 kV on signal ports per IEC 61000-4-4 severity 3.

Listed as current-production lifecycle stage. Substance prohibitance date 07/01/2006 aligns with RoHS compliance. No auxiliary CO contacts on this variant — the 3RB2123-4PD0 is a pure overload relay without integrated auxiliary contacts.

Frequently asked questions

Will 3RB2123-4PD0 drop into a panel that was specified around 3RT1016-1AR11 without rewiring?

The 3RB2123-4PD0 mounts directly to a contactor (contactor mounting), so it fits the same mechanical footprint as the 3RT1016 series contactors. Wiring differs: main terminals are screw-type, auxiliary terminals are spring-loaded — verify terminal assignments against your existing panel drawing.

MPN
3RB2123-4PD0