The IEEE has revised standards for grounding the secondary circuits and cases of instrument transformers and for dry-type distribution and power transformers. It also began work on a new standard for measuring transformer sound levels and on the revision of an instrument transformer testing standard.

One revised standard, IEEE C57.13.3(TM), “Guide for Grounding of Instrument Transformer Secondary Circuits and Cases,” addresses: the grounding of electromagnetic current transformer and voltage transformer circuits; cases of relays and current and voltage transformers; and secondary circuits of opto-electronic current and voltage transformers.

The other revised standard, IEEE C57.12.01(TM), “Standard General Requirements for Dry-Type Distribution and Power Transformers Including Those with Solid-Cast and/or Resin Encapsulated Windings,” was modified by adding reference to NEMA definitions, improved partial discharge requirements and updated testing guidelines. The revision also makes the standard easier to understand.

Work has begun on, IEEE PC57.151(TM), “Sound Level Measurement Guide for Liquid Filled and Dry Type Transformers and Reactors”, a new standard that will consider sound power principles and sound producing sources in transformers and reactors. It also will look at how to optimize sound level measurement accuracy according to test procedures of IEEE C57.12.90 (TM) and IEEE C57.12.91(TM) and at the relationship between factory measurements and sound levels in the field.

Work to revise IEEE PC57.13.5(TM), “Standard of Performance and Test Requirements for Instrument Transformers of a Nominal System Voltage of 115 kV and Above,” will bring this trial-use standard to full standard status. It also will update performance characteristics and provide expanded test requirements.

The IEEE also reaffirmed the continued use of:

• IEEE C57.116(TM), “IEEE Guide for Transformers Directly Connected to Generators.”
• IEEE 1538(TM), “IEEE Guide for Determination of Maximum Winding Temperature Rise in Liquid-Filled Transformers.”

The above standards were sponsored by the IEEE Power Engineering Society.