Overview - IEC 61000-3-11:2017 (EMC, voltage changes & flicker)
IEC 61000-3-11:2017 is the International Electrotechnical Commission standard that defines limits and test procedures for voltage changes, voltage fluctuations and flicker caused by equipment connected to public low‑voltage supply systems. Edition 2.0 (2017) covers equipment with rated input current greater than 16 A up to and including 75 A per phase and equipment that is subject to conditional connection. The standard applies to nominal public low‑voltage systems (typically 220–250 V line‑to‑neutral at 50 Hz) and specifies type‑test methods, evaluation criteria and manufacturer declaration requirements.
Key technical topics and requirements
- Scope and application: Targets equipment with rated current ≤ 75 A that may cause voltage disturbance on public low‑voltage networks and that do not comply with IEC 61000‑3‑3 (≤16 A) under the reference impedance.
- Limits: Specifies limits for voltage changes, voltage fluctuations and flicker (the flicker limits are aligned with IEC 61000‑3‑3).
- Reference impedance (Zref): Uses a conventional reference impedance for measurement, calculation of relative voltage change, and assessment of compliance.
- Conditional connection: Defines the concept where equipment may be connected only if the supply at the interface point has impedance lower than the declared maximum permissible impedance.
- Test and measurement procedures: Includes procedures for type testing, measurement against test impedance, evaluation methods and declaration of compliance.
- Manufacturer declarations: Requires manufacturers to evaluate and declare the maximum permissible system impedance and/or minimum permissible service current capacity for safe connection without exceeding limits.
- Annex A (new in 2017): Explains limitations and effectiveness of the standard when multiple similar items are connected at the same location (penetration and aggregation effects).
Practical applications - who uses this standard
- Manufacturers of industrial drives, motors, heating and power conversion equipment (16–75 A) - to design products that meet public supply compatibility requirements and to prepare compliance documentation.
- EMC test laboratories - to perform type tests, measurements and conformity assessments per the specified procedures.
- Utilities and distribution network operators - to evaluate conditional connections and local connection conditions (impedance, service capacity).
- Certification and compliance bodies - to assess equipment declarations and connection permissions.
- System integrators and facility engineers - to understand connection limits and to avoid supply disturbances in shared low‑voltage networks.
Related standards and references
- IEC 61000-3-3 - limits for equipment ≤16 A (equipment meeting this is excluded from 3‑11).
- IEC TR 60725 - guidance on reference and public supply network impedances for equipment up to 75 A.
- IEC 60050‑161 - EMC vocabulary used by this standard.
Keywords: IEC 61000-3-11, EMC, voltage fluctuations, flicker, low‑voltage supply, conditional connection, reference impedance, rated current ≤75 A, test procedures, manufacturer declaration.