IEC 62271-112:2021

Overview

IEC 62271-112:2021 is the International Electrotechnical Commission standard that defines requirements for alternating current high-speed earthing switches (HSES) used for secondary arc extinction on transmission lines. Applicable to indoor and outdoor installations on systems rated 550 kV and above at 50 Hz and 60 Hz, this second edition (2021) updates the original 2013 edition and aligns with IEC 62271-1:2017. The HSES purpose is to extinguish the residual (secondary) arc that can persist after circuit-breaker fault clearing, improving reclosing reliability and grid safety.

Key Topics

• Scope and definitions: formalizes terms such as secondary arc, single-/multi-phase auto-reclosing schemes, successive fault and HSES classes (e.g., M0 = 1 000 mechanical cycles, M1 = 2 000 cycles).
• Ratings and service conditions: rated voltages, service frequencies and environmental/installation conditions for HSES operation.
• Design and construction: mechanical, electrical and insulation design requirements tailored for very-high-voltage transmission applications.
• Testing requirements: specified type tests and routine tests to verify performance (making/interruption of induced currents, withstand recovery voltages, mechanical endurance).
• Selection and specification guidance: informative guidance (Clause 9 and Annex A) to help choose HSES based on system protection and auto-reclosing schemes.
• Installation, maintenance and safety: rules for transport, storage, installation, operation and maintenance, plus safety provisions.
• Annexes: Annex A provides background on HSES use; Annex B covers induced current/voltage conditions and special coupling scenarios.

Applications and Who Uses It

IEC 62271-112 is essential for:

• Transmission system designers and planners specifying HSES for ultra-high-voltage lines.
• Switchgear manufacturers designing HSES products to comply with international requirements.
• Protection and control engineers integrating HSES into auto-reclosing schemes to mitigate secondary arcs.
• Testing laboratories and certification bodies performing type/routine tests.
• Utility asset managers and maintenance teams responsible for procurement, installation and lifecycle management of HSES.

Practical benefits include increased successful auto-reclose rates, reduced risk of restrike or sustained arcing after breaker operation, and clearer procurement/acceptance criteria.

Related Standards

Relevant cross-references cited in IEC 62271-112:

• IEC 62271-1:2017 - Common specifications for AC switchgear and controlgear
• IEC 62271-100 - AC circuit-breakers
• IEC 62271-102 - Disconnectors and earthing switches
• IEC 62271-200 / -203 - Metal-enclosed and gas-insulated switchgear standards

Keywords: IEC 62271-112, high-speed earthing switches, HSES, secondary arc extinction, transmission lines, high-voltage switchgear, 550 kV, auto-reclosing.