IEC/IEEE 60076-57-129:2017

Overview

IEC/IEEE 60076-57-129:2017 - "Power transformers - Part 57-129: Transformers for HVDC applications" is an international joint IEC/IEEE standard that specifies requirements for liquid‑immersed converter transformers used in high voltage direct current (HVDC) power transmission systems, including back‑to‑back installations. It covers single‑ and three‑phase converter transformers with two, three or multiple windings. This edition cancels and replaces IEC 61378‑2 (2001) and IEEE Std C57.129 (2007).

The standard does not apply to converter transformers for industrial or traction applications (see IEC 61378‑1 / IEEE C57.18.10 and IEC 60310 respectively).

Key topics and technical requirements

IEC/IEEE 60076‑57‑129 defines technical and testing requirements that support safe, reliable HVDC operation. Major topics include:

• General requirements and service conditions - ratings, temperature, load current, AC voltage and direction of power flow.
• Rating data and tolerances - rated voltage, current, frequency and power; short‑circuit impedance tolerances.
• Losses and thermal limits - no‑load and load losses, hot‑spot temperature determination and temperature‑rise testing.
• Comprehensive test regime:
  • Routine, type, special and commissioning tests
  • Dielectric tests (DC withstand, AC applied for valve windings, lightning and switching impulse)
  • Induced voltage tests with partial discharge (PD) measurement
  • Load loss and impedance measurements, short‑circuit tests, insulation power factor, FRA, sound level measurement
• Specialized HVDC topics - valve‑side insulation, polarity reversal tests, extended polarity tests, AC applied voltage on valve side, and induced voltage testing while oil pumps run.
• Ancillary items - bushings (line and valve side), tap‑changer behavior, high‑frequency modelling, rating plate content, and guaranteed sound levels.
• Informative annexes - in‑service overloading guidance for current‑commutated valves, considerations for voltage‑source converters (VSC), and design review topics.

Practical applications

This standard is used to:

• Develop technical specifications for HVDC converter transformers for transmission projects and back‑to‑back stations.
• Define factory acceptance tests (FAT), site acceptance and commissioning tests.
• Guide design verification for insulation, thermal performance, mechanical strength and acoustic performance.
• Support procurement, QA/QC, and compliance checks for HVDC equipment installations.

Who should use this standard

• Transformer manufacturers and design engineers
• HVDC project owners, utilities and system integrators
• Testing laboratories and certification bodies
• Procurement and specification authors for HVDC transmission projects

Related standards

• Replaced: IEC 61378‑2 and IEEE Std C57.129
• Exclusions / see also: IEC 61378‑1 / IEEE C57.18.10 (industrial applications) and IEC 60310 (traction applications)

Keywords: IEC/IEEE 60076‑57‑129, HVDC converter transformers, converter transformers, liquid‑immersed transformers, HVDC transmission, dielectric tests, polarity reversal, partial discharge, temperature‑rise test.