55 kW VFD for pump and fan duty
The ATV21HD55N4 is a 55 kW Altivar 21 AC drive from Schneider Electric, designed for variable-torque loads like pumps and fans. It runs on a 380-480 V three-phase supply and delivers 89 A line current at 480 V (102.7 A at 380 V). The drive is rated for asynchronous motors and includes an integrated Class A EMC filter, meeting EN 55011 Class A Group 1 emissions limits out of the box.
Lifecycle and sourcing reality
The ATV21 series remains a supported product line for pump and fan applications.
Switching frequency and derating
The switching frequency is adjustable from 6 to 16 kHz, with a derating factor required above 8 kHz. Running at 16 kHz quiets motor whine but reduces continuous output current — plan the thermal budget accordingly in the panel. The drive is assembled with a heat sink and must be mounted vertically (±10°). Pollution degree 3 per IEC 61800-5-1 means it tolerates conductive dust in industrial environments, but the heat sink needs free airflow.
Transient overtorque and speed control
The drive delivers 120 % of nominal motor torque for 60 seconds (±10 %), useful for breakaway loads or short-duration overloads on conveyor or crusher starts. Speed accuracy is ±10 % of nominal slip from 0.2 Tn to Tn, and the adjustable PI regulator handles closed-loop process control for pressure or flow regulation.
Communication and fieldbus options
The drive includes a 2-wire RS-485 physical interface with RTU transmission frame, supporting 1 to 247 addresses at 9600 or 19200 bps. Data format is 8 bits, 1 stop, with configurable parity. Optional communication cards add BACnet, LonWorks, Metasys N2, or Apogee FLN — common for building automation integration. The RJ45 connector on the front panel is for the Modbus bus.