IEC 60076-11:2018

Overview

IEC 60076-11:2018 - Power transformers Part 11: Dry-type transformers - is the international standard that defines design, rating, testing and performance requirements for dry-type power transformers (including autotransformers) with highest voltage for equipment up to and including 72.5 kV and at least one winding operating above 1.1 kV. This second edition (2018) cancels and replaces the 2004 edition and includes the March 2019 corrigendum and the July 2020 interpretation sheet. The standard does not apply to certain special or small transformer types (for example gas-filled with non-air gas, small single‑phase or polyphase units below specified kVA limits, instrument, traction, welding, mining, flameproof, testing and voltage‑regulating transformers).

Key topics and technical requirements

• Scope and exclusions: clear voltage and kVA thresholds and explicit exclusions for special transformer types.
• Ratings & identification: rated power, rated voltage/frequency, highest voltage for equipment (U), cooling and enclosure identification (IP00 vs enclosures).
• Thermal management: guaranteed temperature‑rise limits, altitude corrections, temperature‑rise test methods (resistance and superposition), and guidance on where resistance measurements should be taken.
• Dielectric & insulation: insulation levels, induced and separate-source AC withstand tests, partial discharge measurement and lightning impulse testing.
• Environmental & climatic classes: new climatic classes, environmental classes, relation between location and environmental class, and tests for outdoor units without enclosures (salt‑fog, UV).
• Fire behaviour & safety: fire behaviour classes (with special provisions up to 1000 kVA), requirements for materials and testing procedures.
• Mechanical & seismic: introduction of seismic classes and test procedures for mechanical integrity under seismic load.
• Special guidance: recommendations for amorphous‑core transformers and provisions when no dedicated IEC standard exists for special transformers.
• Testing regime: routine, type and additional/special tests, including sound level measurement, short‑circuit ability and climatic/seismic/fire tests.
• Documentation & marking: rating plate requirements, information for enquiries and orders, and installation/safety annex guidance.

Practical applications and intended users

IEC 60076-11 is intended for:

• Transformer designers and manufacturers producing dry‑type power transformers.
• Test laboratories and certification bodies performing type and routine tests.
• Utility engineers, specifiers and purchasing teams writing technical specifications.
• Installation and maintenance personnel for safe operation, mounting and environmental selection.
• OEMs and integrators selecting dry‑type transformers for indoor/outdoor, seismic or fire‑sensitive environments.

Using this standard ensures reliable performance, compliance with international test practices, and consistent selection of dry‑type transformers across industrial, commercial and power utility applications.

Related standards

• Other parts of the IEC 60076 series (power transformer family) - referenced for complementary requirements where applicable.