When a legacy drive specification cites Part 4

IEC 61800-4:2002 was the general requirements and rating standard for adjustable speed AC drive systems above 1,000 V AC. IEC lists it as replaced by IEC 61800-2:2021. For a new enquiry, review the Part 2 framework before carrying an old reference into the purchase specification. The IEC 61800 series distributes performance, EMC and safety requirements across separate documents.

The 35 kV title needs a qualification

The former standard addressed converter line-to-line voltages above 1 kV and up to 35 kV. Its published scope nevertheless stated that requirements above 15 kV were not included; these were to be agreed between the manufacturer and system supplier. The upper figure in the title should therefore not be read as a complete set of uniform requirements for every voltage within that range.

The old scope also distinguished systems using a transformer arrangement with a converter below 1,000 V. For a system above 1 kV using a step-down input transformer and/or step-up output transformer with that low voltage converter, it directed the reader to IEC 61800-2. Record supply, converter and motor voltages separately when identifying the architecture.

What the 2021 consolidation means

IEC 61800-2:2021 revised the 2015 edition and merged the high voltage PDS requirements from Part 4. Its input scope for AC motor systems reaches 35 kV AC and/or 1.5 kV DC. These figures describe document coverage; they are not a voltage range available on every drive. Ratings, functional attributes, installation conditions and their verification now sit within the Part 2 framework.

Define the equipment being assessed

A BDM comprises the converter and its associated control and protection. A CDM adds the relevant feeding and auxiliary sections. The PDS includes the drive module and motor. The pump or conveyor is driven equipment. State that boundary in the enquiry: a torque control capability is not a guarantee of the complete machine’s handling capacity.

Give the supplier a duty profile, not just a kW figure

Start with basic drive parameters, the motor’s rated current, its rated frequency and the required torque. For a constant torque application, distinguish the continuous demand from occasional peaks. Current, duration and repetition interval make an overload requirement comparable with a supplier’s declared capability.

Illustrative enquiry: Specify 80 A continuously, plus 120 A for 20 seconds once every 10 minutes. Ask the supplier to confirm both demands under the stated operating conditions and identify the supporting rating curve. These are example values, not prescribed IEC limits. Suitable motor overload protection must also respect the motor’s thermal capability.

Include the operating range and stopping duty

V/f control and vector control offer different approaches to meeting the process requirement. A shorter acceleration ramp can increase the torque needed to accelerate the load. Prolonged low speed operation can reduce cooling in a self-ventilated motor. Reaching the commanded speed and sustaining the load are separate checks.

Specify how the system handles regenerative energy during deceleration. A braking resistor dissipates energy as heat; a braking chopper controls the associated circuit. Returning energy to the supply requires a suitable converter arrangement. Confirm voltage compatibility, power capacity and duty cycle for the manufacturer’s actual system design.

Review the installation and record meaningful results

Consider voltage drop, cabling and earthing. An input filter must be selected and installed for the relevant EMC arrangement. A component’s declared performance does not establish the performance of every installation containing it.

Keep a record of recurring VFD fault codes. A ground fault indication calls for a different investigation from a low torque indication. For acceptance, record the load, speed range, test conditions and measured outcome. A trip description is a starting point for diagnosis, rather than proof of the underlying cause.

Keep the supporting assessments distinct

IEC 61800-3 addresses EMC; IEC 61800-5-1 addresses hazards including electrical and thermal hazards; IEC 61800-5-2 addresses functional safety. IEC 61800-9-2 covers losses and IE/IES efficiency classification. Explaining the transition from Part 4 to Part 2 does not establish compliance with these additional requirements.

For a documentation update, retain the edition, assessed system boundary, motor data, duty profile and verification evidence together. Map each relevant legacy requirement to the new assessment. Do not assume that an old clause number identifies the same requirement in the replacement edition.

References and sources

IEC 61800-4:2002 | AFNOR — IEC 61800-4 scope | IEC 61800-2:2021 | ABB — Dimensioning of a drive system | ABB — Electrical braking | ABB — EMC installation and PDS definitions | IEC 61800-3:2022 | IEC 61800-5-1:2022 | IEC 61800-5-2:2016 | IEC 61800-9-2:2023+AMD1:2025