IEC 61557-15-2014 PDF

Full title and description

Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. — Equipment for testing, measuring or monitoring of protective measures — Part 15: Functional safety requirements for insulation monitoring devices in IT systems and equipment for insulation fault location in IT systems (IEC 61557-15:2014). This part specifies functional‑safety requirements (based on IEC 61508 principles) that apply to Insulation Monitoring Devices (IMDs) and Insulation Fault Location Systems (IFLS) used in IT (unearthed or impedance‑earthed) low‑voltage distribution systems.

Abstract

IEC 61557-15:2014 defines the safety functions, lifecycle and design requirements needed to reduce functional risk arising from IMDs and IFLSs themselves or from several such devices working together. It is restricted to functional‑safety aspects of the devices (not the application risk assessment or general electrical safety) and is intended to be used alongside IEC 61557‑8 and IEC 61557‑9.

General information

• Status: Published / Active (remains valid and stable until the stability date shown by IEC).
• Publication date: 12 February 2014 (IEC edition 1.0).
• Publisher: International Electrotechnical Commission (IEC).
• ICS / categories: 17.220.20; 29.080.01; 29.240.01.
• Edition / version: Edition 1.0 (2014).
• Number of pages: 154 (IEC published PDF length).

Scope

This part of IEC 61557 is concerned only with functional safety requirements intended to reduce functional risk during the use of IMDs and IFLSs in IT systems. It is limited to risks arising directly from the devices themselves or from multiple devices operating together and defines the basic safety functions these devices should provide. It does not cover application‑specific hazard and risk analyses, general electrical safety requirements (e.g., IEC 61010‑1), nor manufacturing process requirements. It is to be read in conjunction with IEC 61557‑8 (Insulation monitoring devices) and IEC 61557‑9 (Insulation fault location systems).

Key topics and requirements

• Definition and specification of safety functions for IMDs and IFLSs (e.g., local/remote insulation warnings, location warnings, remote enable/disable, transformer monitoring).
• Application of IEC 61508 functional‑safety lifecycle principles (SIL selection, verification, validation, documentation).
• Hardware and software design rules: diagnostics, safe failure fraction (SFF), probability of dangerous failure (PFD) targets and architectural constraints.
• Requirements for lifecycle management, verification, validation, and commissioning evidence for claimed safety functions.
• Integration, modification control and required user documentation for safe installation, operation and maintenance.
• Limitations and responsibilities: the application designer specifies the required SIL and performs the system‑level risk assessment; the standard does not replace application risk analysis.

Typical use and users

Used by manufacturers of IMDs and IFLSs to design and claim functional‑safety properties; by system designers and integrators who specify SILs for IT distribution systems; by safety engineers, test laboratories and certification bodies assessing compliance with IEC 61508‑based functional safety criteria; and by installers and maintenance personnel relying on the product documentation and diagnostics for safe operation. Typical applications include industrial IT networks, medical or critical‑supply installations and other systems where continuous insulation monitoring is safety‑relevant.

Related standards

IEC 61557‑15 is part of the IEC 61557 series (equipment for testing, measuring or monitoring of protective measures). Key related documents include IEC 61557‑8 (Insulation monitoring devices), IEC 61557‑9 (Insulation fault location systems) and the IEC 61508 series (functional safety lifecycle and methods). The standard also notes that it does not replace electrical‑safety standards such as IEC 61010‑1. EN/CENELEC adoptions (EN 61557‑15:2014 / national variants such as DIN VDE EN 61557‑15) exist.

Keywords

Insulation monitoring device (IMD); insulation fault location system (IFLS); IT system; functional safety; IEC 61508; safety integrity level (SIL); diagnostic coverage; safe failure fraction; insulation monitoring; low‑voltage distribution.

FAQ

Q: What is this standard?

A: IEC 61557‑15:2014 specifies functional‑safety requirements for insulation monitoring devices and insulation fault location equipment used in IT (unearthed or impedance‑earthed) low‑voltage distribution systems.

Q: What does it cover?

A: It covers device‑level functional safety: definition of safety functions, lifecycle activities (verification, validation, documentation), hardware/software constraints, diagnostic and failure‑rate considerations, and integration/commissioning requirements. It does not replace system hazard analyses or general electrical safety standards.

Q: Who typically uses it?

A: Manufacturers of IMD/IFLS hardware and firmware, system designers and integrators specifying SILs, safety engineers, test labs and certification bodies, and installers/maintenance staff relying on product diagnostics and documentation.

Q: Is it current or superseded?

A: IEC 61557‑15 was published in 2014 (edition 1.0) and the IEC webstore records a stability date indicating the publication remains valid through 2027. As of 25 February 2026 this edition is still current and has not been superseded; check the IEC webstore or national standards body for any later amendments or revisions after the stability date.

Q: Is it part of a series?

A: Yes — it is Part 15 of the IEC 61557 series (Equipment for testing, measuring or monitoring of protective measures). It is intended to be used with IEC 61557‑8 and IEC 61557‑9 and references IEC 61508 for functional‑safety lifecycle principles.

Q: What are the key keywords?

A: Insulation monitoring device, insulation fault location, IT systems, functional safety, IEC 61508, SIL, diagnostic coverage, safe failure fraction, low voltage, protective measures.