IEC 61558-2-14:2022

Overview

IEC 61558-2-14:2022 is the IEC safety standard for variable transformers and power supply units incorporating variable transformers for general applications. This second edition (2022) replaces the 2012 edition and is a technical revision that aligns structure and references with IEC 61558-1:2017, moves construction descriptions to Part 1, and introduces new symbols for linearly regulated outputs and required current collector position changes. The standard covers transformers that may include electronic circuits, applies mainly to linear power supplies with internal operational frequencies up to 500 Hz, and is designated a group safety publication under IEC Guide 104.

Key topics and requirements

The standard supplements IEC 61558-1 and defines particular requirements and tests specific to variable transformers and related power supplies. Major technical topics include:

• Scope & ratings: applicability to single‑phase and polyphase, stationary or portable, air‑cooled variable auto-, separating-, isolating- and safety-isolating transformers; rated supply voltage ≤ 1 000 V AC; specified rated output limits (e.g., up to 40 kVA single‑phase auto-transformers).
• Classification, marking & information: symbols, identification and essential product information for safe use.
• Electrical safety & protection: requirements for protection against electric shock, insulation resistance, dielectric strength and leakage current.
• Performance under load: tests and limits for output voltage/current under load, no‑load output voltage, short‑circuit voltage, and change of input voltage setting.
• Thermal & overload: heating limits, temperature rise, short‑circuit and overload protection.
• Mechanical & environmental: mechanical strength, ingress protection (dust/moisture), resistance to rusting, and requirements for construction, components and internal wiring.
• Safety distances & earthing: creepage, clearances, distances through insulation, terminals and provisions for protective earth.

Applications and who uses it

IEC 61558-2-14 is essential for:

• Manufacturers and designers of variable transformers and linear power supply units integrating variable transformers.
• Test laboratories, certification bodies and compliance engineers performing safety assessments and type testing.
• Equipment specifiers and purchasers in industrial, laboratory, educational and control systems where adjustable AC supplies are used.
• Safety and maintenance personnel ensuring installations meet international safety requirements.

Practical application notes:

• For switch‑mode power supplies (SMPS) with higher internal frequencies, use IEC 61558-2-16 together with this document; where requirements conflict, the most stringent applies.
• The standard aids in selecting correct construction, marking and protective measures to achieve compliance and safe operation.

Related standards

• IEC 61558-1:2017 (general requirements)
• IEC 61558-2-16 (switch‑mode power supply units)
• IEC 60076-11 (other transformer types - excluded)
• IEC 61140, IEC 60364-4-41, and IEC Guide 104 (safety and group-safety guidance)

Keywords: IEC 61558-2-14, variable transformers, power supply units, safety standard, transformer testing, linear power supply, IEC 61558 series.