Overview
IEC TS 60076-20:2017 - Power transformers, Part 20: Energy efficiency (with corrigendum Jan 2018) is a Technical Specification from IEC TC14 that provides methods and guidance for specifying and evaluating the energy performance of transformers in the scope of IEC 60076-1. Its objective is to promote higher average energy performance, reduce lifetime losses and greenhouse‑gas emissions, and offer a harmonized model for national standards or procurement practices.
Key topics and requirements
- Scope: Applies to power transformers covered by IEC 60076-1 (liquid‑immersed and dry‑type where applicable). Corrigendum January 2018 is included in this edition.
- Energy indices and methods: Defines two methods for an energy efficiency index and introduces three practical evaluation approaches:
- Peak Efficiency Index (PEI) - used with total cost of ownership (TCO) or specified load factors.
- Maximum load and no‑load losses - rationalized limits for mass production and standardization.
- Efficiency at a defined load factor (commonly 50%) - evaluation of real operating performance.
- Calculation and formulas: Presents formulae for efficiency and efficiency‑index calculations to reflect regional practices (50 Hz / 60 Hz distinctions and single‑phase/three‑phase cases).
- Specification and performance levels: Includes procedures for specifying energy performance, tables of PEI and efficiency index targets for different ratings and voltages, and tolerances for losses and indices.
- Annexes: Informative annexes cover capitalisation of losses (TCO concepts), survey of world practices, and country‑specific practices (e.g., Japan).
Practical applications - who uses this standard
- Transformer manufacturers - to design and certify products that meet buyer or regulatory energy targets.
- Purchasers and utilities - to specify procurement requirements using PEI, loss limits, or efficiency‑at‑load methods, and to compare bids on a fair energy basis.
- Regulators and standards bodies - to adopt national performance targets or incorporate harmonized testing/assessment methods.
- Consultants and system planners - to evaluate lifecycle costs, capitalise losses, and select transformers that optimize operating expenditure and emissions.
- Test laboratories - to verify compliance with loss and efficiency measurement and reporting practices.
Related standards
- IEC 60076-1 (rated characteristics and general requirements) - primary scope reference.
- Other parts of the IEC 60076 series for testing, temperature rise, insulation, dielectric tests, and installation considerations.
IEC TS 60076-20 is a practical tool for aligning transformer procurement and design with energy‑efficiency and lifecycle cost objectives, enabling manufacturers, utilities and regulators to adopt consistent, performance‑based criteria.