Single Phase VFD: How to Choose the Right One

A single-phase VFD converts 1-phase 220 V input into 3-phase output to run a small three-phase motor, and it is the right choice when only a domestic or light-commercial single-phase supply is available – typically up to about 2.2 kW. Choose it by checking three things: the drive's single-phase input rating matches your supply, the output rating covers the motor's full-load current, and the control mode suits the load (V/f for fans and pumps, sensorless vector for machines needing low-speed torque). This guide covers power limits, selection criteria, wiring and common mistakes.

What Is a Single-Phase VFD

A single-phase VFD is a standard drive whose input section is designed to accept one phase (typically 220–240 V) and whose output still delivers three phases to the motor. Many low-voltage VFDs are dual-rated: the same unit can take 1-phase or 3-phase input, with a lower power rating on single-phase input because the rectifier carries all the current through one line. This makes them ideal for small pumps, fans, conveyors, packaging machines and workshop equipment where only a wall outlet is available.

Power Limits and Derating

On 1-phase input, the practical limit for a standard LV drive is around 2.2 kW (some up to 3.7 kW in 230 V regions). Above that, the input current and rectifier stress grow quickly, and the drive's rated output on single-phase input is typically derated versus its 3-phase rating. The same ambient-temperature derating rules apply – see our derating guide for the temperature side.

How to Choose a Single-Phase VFD

Wiring and Installation Notes

• Use the dedicated single-phase input terminals (L, N), never connect the third phase terminal on a 3-phase-rated drive
• Check the manual for the input fuse or MCB rating – single-phase input current is higher than 3-phase at the same kW
• Keep the motor cable short or add a filter in domestic environments with sensitive equipment (EMC considerations per IEC 61800-3)
• Mount with airflow clearance and derate for ambient temperature above 40 °C

Frequently Asked Questions

Can I run a 2.2 kW motor from a 1-phase supply? Yes, up to roughly 2.2–3.7 kW with a single-phase-input VFD; beyond that, a phase converter or a 3-phase supply is normally more practical. The drive must be rated for single-phase input – not all drives are.

Does a single-phase VFD output 3-phase? Yes – the output is always three phases; the single-phase input is only the supply side. The motor still runs as a standard 3-phase induction motor.

Not sure which single-phase VFD matches your motor? Our selection team can work from your motor nameplate. See the low-voltage VFD range and the FAQs.