IEC 61557-3-2019 PDF

Full title and description

IEC 61557-3:2019 — Electrical safety in low voltage distribution systems up to 1 000 V AC and 1 500 V DC — Equipment for testing, measuring or monitoring of protective measures — Part 3: Loop impedance. This part specifies requirements for portable and fixed equipment used to measure loop (fault) impedance between a line conductor and protective conductor, between a line conductor and neutral, or between two line conductors using the voltage-drop method when the circuit under test is loaded.

Abstract

IEC 61557-3:2019 defines performance, safety and information requirements for loop-impedance measuring equipment. The 2019 third edition updates the structure to align with the IEC 61557 series and introduces measurement-category requirements and enhanced requirements for operating instructions and user information. It cancels and replaces IEC 61557-3:2007.

General information

• Status: Published / Current (active)
• Publication date: 26 July 2019
• Publisher: International Electrotechnical Commission (IEC)
• ICS / categories: 17.220.20; 29.080.01; 29.240.01
• Edition / version: Edition 3.0 (2019)
• Number of pages: 21 (base publication)

Core bibliographic and status details as published by the IEC webstore.

Scope

This part of IEC 61557 specifies the requirements applicable to equipment for measuring the loop impedance between a line conductor and protective conductor; between a line conductor and neutral; or between two line conductors by using the voltage drop when the circuit under test is loaded. It defines functional requirements, accuracy/uncertainty considerations, safety and marking/operating-instruction obligations and test procedures for verification of conformity. IEC 61557-3:2019 is a technical revision of the previous edition and includes additional requirements for measurement category classification and operating instructions.

Key topics and requirements

• Definition of the loop-impedance measurement function and permitted measurement connections (phase-to-protective conductor, phase-to-neutral, phase-to-phase).
• Performance and accuracy requirements, including uncertainty assessment aligned with the IEC 61557 series guidance.
• Measurement-category (installation and measurement environment) requirements affecting instrument design and user warnings.
• Safety requirements and references to applicable safety standards for measuring equipment (for example IEC 61010 family referenced in normative references).
• Requirements for marking, labelling and operating instructions (user information, warnings, method descriptions and limits of use).
• Test procedures for type and routine verification of instrument performance.
• Alignment of structure and terminology with other parts of the IEC 61557 series to improve consistency across measuring functions.

Typical use and users

IEC 61557-3 is used by manufacturers and designers of loop-impedance and multifunction electrical test instruments, test-lab personnel performing type and verification testing, electricians and maintenance technicians performing installation verification and safety checks, inspection and certification bodies, and standards/regulatory authorities referencing test-equipment requirements for electrical safety verifications.

Related standards

IEC 61557-3 is one part of the IEC 61557 series (equipment for testing, measuring or monitoring of protective measures). Commonly referenced companion parts include IEC 61557-1 (General requirements), IEC 61557-2 (Insulation resistance), IEC 61557-4/5 (resistance to earth / earth-related measurements), IEC 61557-7, -8, -10, -12, -13, -14 and -16 among others in the series; national and regional adoptions (EN/IEC) also exist. Together these parts define the requirements for instruments used to verify protective measures in low-voltage distribution systems.

Keywords

Loop impedance; fault loop; impedance measurement; line-to-protective conductor; phase-to-neutral; voltage-drop method; measuring equipment; low-voltage safety; IEC 61557; measurement category; operating instructions; test instrument performance.

FAQ

Q: What is this standard?

A: IEC 61557-3:2019 is an international standard that specifies requirements for equipment used to measure loop (fault) impedance in low-voltage distribution systems.

Q: What does it cover?

A: It covers the functional, performance, safety, marking and documentation (operating instructions) requirements for loop-impedance measuring equipment and the test procedures used to verify compliance. The 2019 edition updates measurement-category and user-information requirements and aligns the structure with the rest of the IEC 61557 series.

Q: Who typically uses it?

A: Instrument manufacturers, test laboratories, electrical contractors, maintenance and commissioning engineers, inspection bodies and standards/regulatory organizations that specify or verify electrical-safety testing equipment.

Q: Is it current or superseded?

A: IEC 61557-3:2019 is the current (third) edition published on 26 July 2019 and it cancels and replaces IEC 61557-3:2007. The IEC webstore lists the 2019 edition as the active base publication.

Q: Is it part of a series?

A: Yes — it is Part 3 of the IEC 61557 series (Equipment for testing, measuring or monitoring of protective measures). Other parts of the series address insulation resistance, earth/resistance measurements, insulation monitoring, combined equipment functions, and additional specific measuring functions.

Q: What are the key keywords?

A: Loop impedance, fault loop impedance, voltage-drop measurement, line conductor, protective conductor, phase-to-neutral, measuring equipment, measurement category, uncertainty, operating instructions.