IEC 60255

IEC 60255
Title	IEC 60255
Status	Published
Organization	International Electrotechnical Commission
First published	1970s
Domain	Electrical protection relays

IEC 60255 IEC 60255 is an international standard series for electrical protection relays and associated equipment used in power systems and industrial installations. It provides performance criteria, test methods, and definitions for electromagnetic, static, and digital protection devices applied across transmission, distribution, and generation systems. The series interacts with a range of standards, institutions, and technologies that shape modern protection engineering.

Overview and Scope

The series addresses protective relays used in Siemens-class substations, Alstom installations, and systems managed by utilities such as National Grid plc, Électricité de France, and TenneT. It defines functional classes, electrical endurance, and environmental ratings referenced by organizations including the International Electrotechnical Commission, European Committee for Electrotechnical Standardization, and regional bodies like NERC and ENTSO-E. Typical applications include overcurrent, distance, and differential protection employed in networks operated by entities such as Iberdrola, Enel, Duke Energy, and Southern Company. The scope overlaps with standards from IEEE, IEC 61850, and product families from manufacturers like ABB, Schneider Electric, and General Electric.

Historical Development and Revisions

Development of the series was influenced by early relay technologies from firms such as Westinghouse and Mitsubishi Electric, and by events including the Northeast blackout of 1965 and the Northeast blackout of 2003, which drove updates to performance requirements and system coordination. Revision cycles involved committees with national committees from British Standards Institution, DIN, and AFNOR, and experts affiliated with research centers like EPRI and Cigre. Subsequent editions incorporated changes prompted by advances in digital signal processing, the adoption of microprocessor relays from vendors such as SEL and GE Grid Solutions, and harmonization efforts following initiatives led by IEC Technical Committee 95 and liaison with ISO.

Technical Structure and Parts

The standard is organized into multiple parts covering terminology, common test procedures, and device-specific requirements. Parts address electromagnetic compatibility considerations that reference immunity frameworks used by ITU-T and CENELEC, while mechanical and climatic tests align with criteria from ISO 9001-certified manufacturers. Detailed sections specify requirements for relay types deployed by operators like National Grid ESO and RWE, and for systems integrating communication protocols standardized by IEC 61850 and legacy schemes used by utilities such as Tokyo Electric Power Company and KEPCO.

Application and Use in Protection Relays

Protection engineers in utilities including PG&E, Hydro-Québec, and State Grid Corporation of China apply the series when selecting relays for transmission and distribution projects. The standard guides procurement of relay families used in interconnection projects managed by ENTSO-E, MISO, and PJ M. Relay protection schemes for assets from manufacturers like Hitachi Energy and Toshiba reference the series when implementing distance protection, differential schemes, and breaker failure protection used in installations such as offshore wind farms owned by Ørsted and hydro plants operated by Statkraft. Coordination studies and protection settings frequently integrate tools from academic labs at ETH Zurich and Imperial College London.

Test Methods and Performance Requirements

Test procedures specified in the series cover steady-state accuracy, dynamic performance, timing, and stability under fault conditions. Laboratories accredited under bodies like ILAC and national accreditation entities such as UKAS and DAkkS perform compliance testing using equipment from suppliers like Megger and Omicron. Performance metrics used by grid operators such as CAISO and ERCOT are derived from these procedures, while incident analyses from events like the 2012 India blackouts and reliability assessments by Cigre Study Committees have informed tolerance and endurance criteria. Climatic, vibration, and seismic tests reflect requirements relevant to installations in regions governed by authorities such as FERC and KEMA.

Compliance, Certification, and Standards Harmonization

Compliance processes involve certification bodies and testing laboratories recognized by national standardization agencies, and manufacturers seek declarations of conformity to satisfy procurement specifications of utilities including E.ON and Centrica. Harmonization efforts coordinate the series with IEEE Standards Association documents and regional norms from AS/NZS and BSI, while input from consortiums like CEER and research networks such as H2020 projects influence interoperability with communication standards like MMS and IEC 61850-8-1. International procurement and grid code compliance for projects with companies like Siemens Energy and ABB Power Grids typically reference the series as part of conformity assessment and type testing.

Category:IEC standards