Drive selection memo — FRN250AR1S-4U
The Fuji FRN250AR1S-4U is a FRENIC-HVAC series variable frequency drive rated for 250 HP on a 3-phase 460 V supply, in a UL open-type enclosure. This is the HVAC-optimized variant of the FRENIC family, meaning the firmware includes pre-loaded pump and fan macros, sleep/wake functions, and fire mode override — features a general-purpose drive would need custom programming to match. The 460 V class and 250 HP rating place it squarely in the mid-to-large commercial HVAC segment — think chiller compressors, cooling tower fans, and primary/secondary chilled water pumps. The UL open-type chassis means it's intended for panel mounting, not standalone wall mount; plan for adequate enclosure ventilation or a forced-air cooling plenum.
The 250 HP rating at 460 V three-phase is the motor output capacity under typical HVAC load profiles (variable torque). That means it's sized for a 250 HP motor driving a centrifugal fan or pump — not a constant-torque conveyor or extruder. If the application is a positive-displacement load, the drive must be oversized by one frame; the FRENIC-HVAC firmware is not tuned for constant-torque starting. The UL open-type designation means the drive carries UL listing for the US market but lacks a NEMA 1 or 12 enclosure. It must be installed inside a UL-listed industrial control panel with appropriate short-circuit current rating (SCCR) coordination. The open-type rating also implies the heatsink is exposed — verify panel depth allows adequate airflow behind the drive.