IEC 61557-12:2018

Overview

IEC 61557-12:2018 - Electrical safety in low voltage distribution systems - Part 12 specifies requirements for power metering and monitoring devices (PMD) used in low-voltage distribution systems up to 1 000 V AC and 1 500 V DC. The standard defines performance, classification and tests for fixed or portable PMD intended for indoor and/or outdoor industrial and commercial applications. It focuses on measurement and monitoring of electrical quantities (power, energy, voltage, current, harmonics, unbalance, dips/swells, etc.) and the related uncertainty and performance requirements. IEC 61557-12:2018 supersedes the 2007 edition, includes corrigendum 1 (2022) and introduces major updates such as three PMD categories and new informative annexes (applications and power factor conventions).

Key topics and technical requirements

• Scope and applicability: Covers PMD performance in single- and three-phase AC or DC systems up to rated voltages given above. Does not apply to revenue electricity meters (IEC 62053 series), power quality instruments (IEC 62586), IEC 60051 analogue instruments, or parameters covered by other parts of IEC 61557.
• Classification and functions: Defines three categories of PMD with minimum required functions for each category and recommended sensor classes (Annex F).
• Measured parameters: Requirements for active/reactive/apparent power & energy, frequency, RMS currents and voltages, power factor, harmonics/THD, flicker, voltage dips/swells/interruption, transients, unbalance, demand/peaks and related derived quantities.
• Performance and uncertainty: Specifies intrinsic and operating uncertainty concepts and tests; uncertainties for active/reactive energy are derived from IEC 62053 definitions.
• Architecture and sensors: Defines PMD structures with or without external sensors, requirements for self-powered PMD, and system performance classes when external sensors are used.
• Tests and compliance: Type and routine tests covering intrinsic uncertainty, environmental influences (temperature, vibration, climatic), EMC, start‑up, gapless measurement and safety tests.
• Marking and documentation: Requirements for marking, installation and operating instructions, and essential characteristics to be declared.

Practical applications and who uses it

• Intended for engineers, manufacturers, test laboratories, installers and facility managers who specify, design, test or deploy PMD for:
  • Energy management and submetering in commercial and industrial buildings
  • Load verification, fault diagnosis and verification of protective measures
  • Monitoring distributed generation, DC/AC microgrids and distribution assets
• Useful for procurement specifications, type testing, product conformity and system integration.

Related standards (brief)

• IEC 62053 (electricity metering) - revenue meters (not covered here)
• IEC 62586 (power quality instruments) - PMD-A relocated coverage
• Other parts of IEC 61557 cover complementary measurement parameters and safety testing

Keywords: IEC 61557-12:2018, power metering and monitoring devices, PMD, low voltage distribution, power monitoring, energy measurement, uncertainty, PMD categories, IEC standards.