75 kW VFD for HVAC — normal and heavy duty ratings
The ATH650D75N4 is a wall-mount AC drive from the Altivar HVAC ATH600 series, rated 75 kW (100 hp) normal duty and 55 kW (75 hp) heavy duty at 480 V input. The heavy-duty rating governs constant-torque loads like screw compressors or belt conveyors; the normal-duty figure applies to variable-torque fan and pump applications where overload margin is lower. Line current at 480 V is 113 A normal duty, 86.9 A heavy duty — the heavy-duty current is the one to size input fusing and contactors against if the drive runs a constant-torque load. Apparent power is 93.7 kVA normal duty, 72.2 kVA heavy duty.
Safety function and compliance package
Safe Torque Off (STO) is built in, certified SIL 3 per IEC 61508 and PL = e per ISO 13849-1. That means the drive can be integrated into a safety circuit without an external contactor for the power removal function — the STO input removes torque-producing energy at the gate-drive level. The drive carries CE, UKCA, cULus, EAC, RCM, ATEX, WEEE, RoHS, and KCC markings, with standards compliance to UL 61800-5-1, EN/IEC 61800-3 (EMC), EN/IEC 61800-5-1, IEC 61000-3-12, IEC 60721-3, IEC 61508, and ISO 13849-1. The integrated Class C3 EMC filter covers most industrial environments without an external filter for conducted emissions.
Application functions and fieldbus options
Built-in functions include fire mode, forced fire mode, PID controller with three additional PID sets, damper control, underload detection for broken belt, scroll compressor management, skipped frequencies, catch on the fly, power monitoring, and cybersecure firmware update. These are HVAC-specific — the fire mode overrides normal protection to keep the fan running during a fire event, and the PID set handles multi-zone pressure or temperature control. Communication options cover BACnet IP, PROFINET, Ethernet IP/Modbus TCP via option cards, plus a 2-wire RS-485 port supporting Modbus RTU and BACnet MS/TP at baud rates up to 76.8 kbit/s. The RJ45 and open-style terminal connectors give flexibility for both pre-terminated patch cables and field-wired screw terminals.