The ATV21HD18M3X is an Altivar 21 variable speed drive sized for a 18.5 kW asynchronous motor on a 200-240 V three-phase supply. Line current draws 55.8 A at 240 V, so the upstream protection and cabling need to be rated for that draw. The switching frequency is adjustable from 6 to 16 kHz; running above 8 kHz requires derating the output current, which matters if you are trying to quiet a motor on a fan or pump load. The drive includes an adjustable PI regulator for closed-loop process control, and the Modbus RTU over RS-485 interface runs at 9600 or 19200 bps with RTU framing. For building management integration, optional communication cards support BACnet, LonWorks, Metasys N2, or APOGEE FLN.
The drive is assembled with a heat sink and must be mounted vertically within ±10 degrees. Operating altitude is limited to 1000 m standard, with derating up to 3000 m; note the 2000 m restriction for corner-grounded distribution networks. Pollution degree 2 per IEC 61800-5-1 applies, meaning the enclosure is suitable for typical control-room environments.