Several of the subcommittees under the IEEE Transformers Committee are doing significant work. This report covers work in the last two quarters of 2018.
Insulating Fluids Subcommittee
C57.104, IEEE Guide for the Interpretation of Gases Generated in Oil-Immersed Transformers (DGA) is being revised and will change how DGA results will be interpreted. It went out to the working group for ballot in summer 2018 and passed; however, a significant number of comments were submitted. As a result, the committee is reviewing all of the comments and will prepare a new draft of the guide for the members to review in 2019. This guide is only for mineral-oil filled transformers. It’s important to recognize that different fluids have different gassing characteristics. As such, this guide is not applicable to the gassing of other fluids such as natural esters.
C57.147, IEEE Guide for Acceptance and Maintenance of Natural Ester Insulating Liquid in Transformers was updated and published in July, 2018. This guide is only for the fluid qualities of natural esters and does not include DGA limits. Dissolved gas thresholds can be found in C57.155, IEEE Guide for Interpretation of Gases Generated in Natural Ester and Synthetic Ester-Immersed Transformers.
A new Working Group was established in 2018 for C57.166, IEEE Guide for Acceptance and Maintenance of Insulating Liquids in Transformers and Related Equipment. Work is just beginning, but the goal is to combine the various fluid guides into a single guide. As a result, the user will be able to reference one IEEE guide to research the limit values of a specific fluid quality test, such as the minimum acceptable dielectric value, regardless of the fluid type (mineral oil, silicone, natural ester, etc.).
Power Transformer Subcommittee
Within the Power Transformer Subcommittee, C57.93, IEEE Guide for Installation and Maintenance of Liquid-Immersed Power Transformers, was revised and went out to ballot to the working group in 2018. The revision passed and has gone through a second recirculation to resolve questions raised during the review. This updated guide, which is applicable to transformers 501 kVA and larger, with a secondary voltage of 1,000 Volts or higher, is expected to be published in 2019.
Separately, a task force within the Power Transformer Subcommittee studied the level of interest in developing a new guide for the industry to use in performing a condition assessment on a transformer and concluded there is sufficient value in creating a new guide. The next step will be to develop a title, scope, and purpose for this guide so it can be submitted for review and approval. If approved, work can begin on developing this new guide.
In other areas of the Power Transformer Subcommittee, work continues toward updating C57.143, IEEE Guide for Application for Monitoring Equipment to Liquid-Immersed Transformers and Components; C57.150, IEEE Guide for the Transportation of Transformers and Reactors Rated 10,000 kVA or Larger; and C57.148, IEEE Standard for Control Cabinets for Power Transformers.
Within the Bushing Subcommittee, C57.19.01, IEEE Standard for Performance Characteristics and Dimensions for Power Transformer and Reactor Bushings was revised and published in July, 2018. This guide covers electrical, dimensional, and related requirements for power transformer and reactor bushings that have basic impulse insulation levels (BILs) of 150 kV and above.
Finally, work continues on updating C57.19.00, IEEE Standard General Requirements and Test Procedure for Power Apparatus Bushings. This guide was last updated and published in 2004.
Scott Reed is President of MVA Diagnostics, which specializes in the diagnostic analysis of oil in substation transformers throughout the United States. He received a BS in electrical engineering from North Carolina State University with a concentration in power and joined Baltimore Gas & Electric performing relay system protection design work. Scott serviced transformers, including vacuum filling, oil processing, repairing, electrical testing, and oil testing for 25 years before founding MVA Diagnostics. He has written and published various papers for the industry and is very active with the IEEE Transformer Committee, where he serves as the Secretary for the IEEE Insulating Fluids Subcommittee; Vice Chairman of IEEE Std. C57.166, Acceptance and Maintenance of Insulating Liquids in Transformers; and Secretary of IEEE Std. C57.93, Installation and Maintenance of Liquid Immersed Power Transformers.