Sourcing rotary phase converters from China

Duty on rotary phase converters

Heading 8502 covers electric generating sets and rotary converters. For this guide, the relevant supplied line is 8502 40 00 90, electric rotary converters, other. The table shows buying configurations under that same line, rather than separate tariff bands. Confirm classification for the actual assembly supplied. For diesel rotary UPS equipment, see our diesel rotary UPS sourcing guide.

Read from the UK Trade Tariff on 1 October 2026, the relevant line carried 0% duty for goods from China. The supplied tariff record lists no anti-dumping or countervailing measure, suspension or attached import control. Import VAT is normally 20%; see the import duty and VAT guide.

Give your broker the operating description, circuit diagram and details of the rotating machine and controls when confirming the commodity code. For the wider heading context, see the rotary frequency converter guide.

Specify the supply and motor starting load

Write down the available input supply, required output voltage and phases, frequency, connected motor ratings and which machines may run together. Describe the hardest starting load, including whether a compressor or pump starts against pressure. Ask the factory to demonstrate starting and sustained operation with a representative load, rather than approving an unloaded demonstration.

Define the rotating unit, capacitor bank, starting circuit, contactors, overload protection, enclosure, cooling and terminal layout. Agree acceptable voltage balance under the intended loads, restart behaviour after a supply interruption and the spare components to accompany the order. Check compatibility separately for machinery containing electronic controls.

For electrical equipment within the voltage scope of the safety regulations, confirm the conformity assessment, technical documentation, declaration of conformity and CE or UKCA marking requirements for the Great Britain market with the relevant authority. Importers must check the manufacturer's assessment, provide their identifying details and ensure understandable English instructions accompany the equipment. Electromagnetic compatibility rules cover equipment liable to generate disturbance, subject to exceptions. Check hazardous-substance scope and producer registration separately with your testing and certification adviser.

Worked duty example

Illustrative example, not a quote: 16 enclosed rotary phase converters, illustrative order under 8502 40 00 90, invoiced at £20,000 free on board, with £1,500 of freight and insurance to the UK. The customs value is £21,500. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £21,500, so it is £4,300. With no duty, the only import tax is the VAT, which a VAT-registered importer can usually reclaim. The import duty and VAT guide explains each step.

Inspection checklist

Load test: record input current, output voltages between phases and voltage balance during starting and sustained operation with the agreed machinery load.

Controls and protection: compare capacitors, contactors, overload settings and terminal markings with the approved circuit diagram; demonstrate start, stop and agreed restart behaviour.

Construction and arrival: check earth continuity and insulation through a competent tester; inspect guards, ventilation, cable entries, mounting feet and transit damage before energising.

Documents and identity: match the delivered model and rating plate to the declaration, test reports and English instructions. Use the agreed inspection checklist before shipment and repeat condition checks on arrival.

What goes wrong

A converter can run an unloaded motor yet struggle when the customer's machine starts under load. Poor voltage balance can create uneven motor currents and heating. Incorrect capacitor selection, loose terminals or unsuitable control components can produce unreliable starting. Test the intended operating combination and record the results against the agreed specification.

A separate control cabinet can arrive with wiring or components different from the tested sample. Missing connection instructions leave the installer guessing which output terminals serve the machinery controls. Freeze the circuit diagram and component list, check changes before shipment and have a competent installer assess the delivered assembly before connection.

Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For components and parts, see sourcing for manufacturers.