Overview
IEC 60947-4-2:2020 (consolidated with Amendment 1, edition 4.1) is the International Electrotechnical Commission standard for low-voltage switchgear and controlgear covering semiconductor motor controllers, starters and soft-starters intended for circuits with rated voltages up to 1 000 V AC. This fourth edition cancels and replaces the 2011 edition and constitutes a technical revision that updates scope exclusions, safety rules, EMC and measurement requirements, and alignment with IEC 60947-1:2020.
Key topics and requirements
- Scope and classification: Defines types of semiconductor motor controllers, starters and soft-starters and their intended operating conditions (rated voltages ≤ 1 000 V AC).
- Safety aspects: New/updated requirements for general safety, limited energy circuits, electronic circuits, stored-charge energy circuits and dedicated wiring accessories.
- Performance and construction: Requirements for materials, clearances/creepage, terminals, enclosures, and provisions for earthing and isolation.
- Rated and limiting values: Specification of rated voltages, currents, frequencies, duty cycles, temperature-rise and power losses for semiconductor equipment.
- Coordination and protection: Rules for coordination with short-circuit protective devices (SCPD) and verification of crossover current behavior (see normative annexes).
- EMC and power consumption: Immunity and emission tests plus guidance on power consumption measurement.
- Tests and verification: Type, routine, sampling and special tests including abnormal operating tests and EMC tests; annexes cover marking, terminal identification and coordination test procedures.
- Documentation and marking: Requirements for product information, installation/maintenance instructions and terminal marking (Annex A normative).
- Standards alignment: Includes reference to IEC 62683-1 and alignment with IEC 60947-1:2020.
Applications and who uses it
This standard is essential for:
- Manufacturers of semiconductor motor controllers, starters and soft-starters to design, test and certify products.
- Test laboratories and conformity assessment bodies performing type and routine tests.
- Panel builders, OEMs and electrical contractors specifying and installing low-voltage motor control equipment.
- Design and safety engineers ensuring coordination with SCPDs, EMC compliance and safe wiring practices.
- Procurement and compliance teams verifying product markings, datasheets and installation instructions.
Practical uses include product design validation, selecting starters and soft-starters for motors, preparing technical specifications, and ensuring safe installation and maintenance in industrial and commercial motor-control applications.
Related standards
- IEC 60947-1:2020 (general rules for low-voltage switchgear and controlgear) - alignment and cross-references.
- IEC 62683-1 - referenced for related requirements.
Keywords: IEC 60947-4-2, semiconductor motor controllers, soft-starters, low-voltage switchgear, motor-starters, SCPD coordination, EMC, limited energy circuits, IEC 60947-1.
Open preview (PDF)Low-voltage switchgear and controlgear – Part 4-2: Contactors and motor-starters – Semiconductor motor controllers, starters and soft-starters
