The Schneider Electric ATV21WU55N4 is a 5.5 kW (7.5 HP) variable-frequency drive from the Altivar 21 family, built on a 380–480 V three-phase supply with an integrated class A EMC filter and an IP54 enclosure. Its target application is HVAC — centrifugal pumps, cooling-tower fans, air-handling units, and condenser-water loops where the drive lives in a mechanical room rather than a clean panel.
This drive is obsolete. Schneider announced the phase-out of the Altivar 21 series and the recommended successor is the ATV212 range. The direct cross-reference for the ATV21WU55N4 is the ATV212WU55N4 — same power rating, same voltage class, updated control board with native BACnet support instead of requiring an option card.
If your facility runs a fleet of ATV21 drives and you want to keep a common spare on the shelf, we can still source the ATV21WU55N4 through independent channels. Reference pricing is approximately $1,408 but varies with availability — the obsolete status means pricing moves with remaining channel inventory.
Key ratings
| Parameter | Value |
|---|---|
| Motor power | 5.5 kW (7.5 HP) |
| Supply | 380–480 VAC, 3-phase, 50/60 Hz |
| Line current | 10.9 A at 380 V / 8.6 A at 480 V |
| Output current (cont.) | 12 A |
| Transient overtorque | 120% × Tn for 60 s |
| Switching frequency | 6–16 kHz (derate above 12 kHz) |
| Enclosure | IP54 |
| EMC filter | Class A, integrated |
| Dimensions (H×W×D) | 340 × 230 × 208 mm |
| Weight | Approx. 11 kg |
| Communication | Modbus RTU (RS-485); optional BACnet / LonWorks / METASYS N2 cards |
What the IP54 enclosure means in an HVAC mechanical room
IP54 is dust-protected and splash-proof from any direction — not washdown-rated, not immersion-rated. That is the right enclosure class for a drive mounted on a wall next to a chiller or in a fan penthouse where it might see condensation drips or a stray hose spray during coil cleaning. It is not sealed well enough for a cooling-tower deck exposed to direct weather. If your mechanical room is unconditioned and hits 40 °C ambient in summer, derate output current by approximately 2.5% per degree above 40 °C up to the 50 °C maximum.
If you are replacing one that failed
Before ordering a replacement, check the nameplate on the failed drive:
- ATV21WU55N4 vs ATV21WU55N4C — the "C" variant has a different EMC configuration for IT (ungrounded) supplies. Do not swap them without checking the supply type.
- The drive stores parameters in non-volatile memory. If the old drive still powers up, upload the parameter set via the RJ45 Modbus port before disconnecting it. The ATV212 successor does not directly import ATV21 parameter files — you will need to re-enter the motor nameplate data, ramp times, and PI loop gains manually.
Sourcing
We can quote the ATV21WU55N4 as long as channel inventory exists. If your timeline allows, we recommend the ATV212WU55N4 successor instead — it is in active production, BACnet is native, and lead times are shorter. Send your BOM for a line-item quote covering the drive plus any option cards and line reactors.