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Siemens 3RV2121-4NA10 — Motor Protection Circuit Breakers (MPCB)

Siemens 3RV2121-4NA10 SIRIUS Motor Protection Circuit Breake

MPN3RV2121-4NA10
Active

Siemens SIRIUS motor protection circuit breaker, 3RV2121-4NA10, Trip Class 10, for motor protection with overload relay function, screw-type terminals, 25 kA breaking capacity at 400 V, 65 mm width.

Siemens 3RV2121-4NA10 datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

3RV2121-4NA10 — Identification
ParameterValue
SeriesSIRIUS
Product designationCircuit breaker
Frame sizeS0
3RV2121-4NA10 — Electrical
ParameterValue
Rated operational current (Ie)28 A
Rated voltage20 ... 690 V
Rated voltage, AC-3 (max.)690 V
Rated frequency50 ... 60 Hz
Rated insulation voltage (Ui), pollution degree 3690 V
Rated impulse withstand voltage (Uimp)6 kV
Number of poles3
Power loss (AC, hot)13.25 W
Power loss, per pole (AC, hot)4.4 W
3RV2121-4NA10 — Protection & Tripping
ParameterValue
Overload release setting range23 ... 28 A
Instantaneous short-circuit trip current364 A
Trip classCLASS 10
Breaking capacity at 240 V (AC)100 kA
Breaking capacity at 400 V (AC)55 kA
Breaking capacity at 500 V (AC)10 kA
Breaking capacity at 690 V (AC)4 kA
Breaking capacity at 240 V100 kA
Breaking capacity at 690 V2 kA
Short-circuit trip typemagnetic
Overload release typethermal
Short-circuit protectionYes
Phase-failure detectionYes
Ground-fault detectionNo
Auxiliary switch extendableYes
3RV2121-4NA10 — Endurance & Switching
ParameterValue
Endurance, main contacts (typ.)100 000
Endurance, auxiliary contacts (typ.)100 000
Switching frequency, AC-3 (max.)15 1/h
Auxiliary CO (changeover) contacts0
3RV2121-4NA10 — Connections
ParameterValue
Main-circuit terminal typescrew-type terminals
Main-circuit connector arrangementTop and bottom
Conductor cross-section, solid / 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 contacts)2x (16 ... 12), 2x (14 ... 8)
3RV2121-4NA10 — Mechanical
ParameterValue
Height97 mm
Width65 mm
Depth97 mm
Mounting methodscrew and snap-on mounting onto 35 mm DIN rail according to DIN EN 60715
Mounting positionany
3RV2121-4NA10 — Environmental
ParameterValue
Operating temperature-20 ... +60 °C
Storage temperature-50 ... +80 °C
Transport temperature-50 ... +80 °C
Relative humidity (operation)10 ... 95 %
Max. installation altitude2 000 m
3RV2121-4NA10 — Specifications
ParameterValue
Design Of The ProductFor motor protection with overload relay function

Product details

It's a current-production part, so no last-time-buy scramble — this one's still a standard line item.

Integration Notes

Screw-type terminals on the main current circuit accept 2× (0.5 to 1.5 mm²) solid or stranded, or 2× (0.75 to 2.5 mm²). M4 bolts on the main contacts. Rated operational voltage covers 20 to 690 V, so it handles everything from 24 V control transformers up to 690 V motor feeds. At 230 V it's rated for 5 hp; at 200/208 V, 7.5 hp — useful for North American dual-voltage motor nameplates.

MPN
3RV2121-4NA10