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Siemens 3RT1934-5AC21 — Contactors

Siemens 3RT1934-5AC21 SIRIUS Magnet Coil, 24 V AC, Size S2

MPN3RT1934-5AC21

Siemens SIRIUS 3RT1934-5AC21, Size S2 magnet coil, 24 V AC 50/60 Hz, screw terminal, phased-out product.

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

3RT1934-5AC21 — Control & Coil
ParameterValue
Control supply voltage typeAC
Rated value @ 50 Hz0.8 ... 1.1
Rated value @ 50 Hz24 V
3RT1934-5AC21 — Other specifications
ParameterValue
At 60 Hz rated value24 V

Product details

The Siemens SIRIUS 3RT1934-5AC21 is a replacement magnet coil for Size S2 contactors in the SIRIUS family. The coil's operating range at 50 Hz is 0.8 to 1.1 times the rated voltage, meaning it'll pull in reliably down to about 19.2 V and hold up to 26.4 V before the thermal limit starts to matter.

This coil mounts onto SIRIUS Size S2 contactors via screw terminals. The 24 V AC control voltage is common across European panel designs — it shares the same transformer tap as the PLC and HMI supplies in most cabinets.

Frequently asked questions

What replaces the 3RT1934-5AC21?

The official successor is the SIRIUS 3RT2 series. That's a different contactor platform, so verify the mounting footprint and coil voltage before substituting — it's not a direct mechanical swap without checking the full contactor assembly.

What are the coil voltage and frequency ratings?

The coil is rated 24 V AC at both 50 Hz and 60 Hz. The operating range at 50 Hz is 0.8 to 1.1 times the rated voltage, so it pulls in between about 19.2 V and 26.4 V.

Will the 3RT1934-5AC21 fit a panel built around the 3RT7027-1AC25?

No — the 3RT1934-5AC21 is a Size S2 coil, while the 3RT7027-1AC25 is a Size S0 contactor. The mounting hole pattern and coil geometry are different. You'd need the correct coil for the S0 frame, not this one.

MPN
3RT1934-5AC21