Overview
IEC 60947-2:2016 (Edition 5.0) is the International Electrotechnical Commission standard that specifies requirements for low-voltage circuit-breakers used in switchgear and controlgear. It applies to circuit-breakers with main contacts intended for circuits with rated voltages up to 1 000 V a.c. or 1 500 V d.c. and includes additional rules for integrally fused circuit‑breakers. This fifth edition is a technical revision (cancelling the 2006 edition and subsequent amendments) and adds new test and application annexes for modern uses such as photovoltaic systems and residual‑current devices with auto‑reclose.
Key Topics and Requirements
- Scope and classification: Types of circuit‑breakers, rated voltages, currents, frequency and duty, and utilization (selectivity) categories.
- Construction and safety: Mechanical and electrical design requirements including clearances, creepage, operator safety, isolation capability, withdrawable designs and provisions for neutral poles.
- Performance characteristics: Making, breaking and short‑circuit behaviour; rated service and ultimate breaking capacities; short‑time withstand; temperature rise; dielectric strength and EMC considerations.
- Releases and protection functions: Overcurrent, undervoltage, shunt and residual current functions, including marking and calibration checks.
- Testing regimes: Defined type tests, routine tests, mechanical operation, dielectric, temperature‑rise, short‑circuit breaking, short‑time withstand, and special tests (damp heat, salt mist, vibration, shock). New or highlighted tests include:
- Tests for verification of selectivity between upstream/downstream devices (Annex A, see A.5.3).
- Critical load current tests for d.c. circuit‑breakers (8.3.9).
- New Annex P covering circuit‑breakers for photovoltaic applications.
- New Annex R for residual‑current circuit‑breakers with automatic reclosing.
- Product information & documentation: Required marking, installation/operation/maintenance instructions and coordination data.
Applications and Who Uses It
IEC 60947-2 is essential for:
- Circuit‑breaker manufacturers designing and certifying low‑voltage breakers for AC and DC systems.
- Test laboratories and certification bodies performing type and routine testing to demonstrate compliance.
- Electrical designers and specifiers selecting breakers for industrial, commercial and renewable energy installations (notably photovoltaic systems).
- System integrators and plant engineers implementing short‑circuit coordination, selectivity and back‑up protection strategies.
- Installers and maintenance personnel using the standard’s marking, installation and safety requirements.
Keywords: IEC 60947-2, circuit‑breakers, low‑voltage switchgear, short‑circuit protection, selectivity tests, photovoltaic circuit‑breakers, DC circuit‑breaker testing, residual‑current breakers.
Related Standards
- IEC 60947-1 - Low‑voltage switchgear and controlgear: General rules (referenced throughout IEC 60947‑2).
- Other parts of the IEC 60947 series covering contactors, motor controllers and auxiliary devices.