Drive selection memo for a 0.75 kW motor
The Mitsubishi FR-D740-0.75K-CHT is a D700 series inverter sized for a 0.75 kW three-phase induction motor on a 380-480 V line. Its 2.2 A rated output and 1.7 kVA capacity match the full-load current of a standard 0.75 kW motor at 400 V, so the drive runs at nameplate without derating. The 150% overload for 60 seconds (200% for 0.5 s) handles short-duration high-torque events like starting a loaded conveyor or breaking away a sticky pump — the inverse-time characteristic means it lets the motor pull hard briefly but trips fast on a sustained stall. Input tolerance is wide: three-phase 380-480 V at 50/60 Hz, with permissible fluctuation from 325 to 528 V. That covers nominal 400 V and 480 V grids globally, plus saggy sites where line voltage drops under heavy load. The 2.5 kVA power supply capacity gives headroom for the DC bus charging circuit and internal losses.
What the overload rating buys you
The 150% overload for 60 seconds is the figure that governs real-world motor starting and intermittent overloads. For a 0.75 kW pump or fan, that means the drive can deliver 3.3 A (150% of 2.2 A) for a full minute to accelerate the load — enough for most direct-on-line starts. The 200% for 0.5 s covers the magnetizing inrush when the motor first picks up. The regenerative braking torque of 100% means the drive can absorb full rated torque during deceleration without an external braking resistor, as long as the duty cycle is moderate.