A White Paper Created by a Task Force of the IEEE TC Sub-Committee on Standards
Recommendations to the IEEE Transformer Committee (TC) on Recommended Changes, Deletions, and Insertions Related to Normalizing the References of Insulating Liquids throughout the
IEEE TC Standard Series.
Contents
General Statement of Purpose
Background on the Need for the White Paper
The White Paper Task Force
Classification of Issues and Areas in Need of Review
1.Omissions of various alternative insulating liquids in existing clauses even though inclusion is technically valid
2.Clauses where generic oil terms are used but should be limited to certain insulating liquid(s) for technical reasons
3.Clauses where revisions may be necessary based on different technical properties of insulating liquids
4.Clauses where the same insulating liquid type is referred to with different nomenclatures
5.Clauses where different terms are being used interchangeably
Additional Guidance for Reviewing Standards for Insulating Liquid Term Normalization.
Acknowledgements
ANNEX A – General Definitions
ANNEX B – Examples of Recommended Changes
General Statement of Purpose
The objectives of this white paper are to 1) support improved consistency and technical accuracy of the terms related to various insulating liquidsand 2) provide a tool to guide those involved with Transformer Committee standards’ development. The suggestions provided in this guide are not mandatory for the Working Groups when revising standards. However, it is the wish of the Standards Subcommittee (SC) that these recommendations be carefully considered when standards are under revision.
Background on the Need for the White Paper
When IEEE Transformer Committee standards were first developed, the vast majority of liquid-filled transformers used mineral oil-based insulating liquids. Until the 1970s, the only significant alternatives to mineral oil were fire-resistant askarel-based insulating liquids. After the demise of askarel, several alternative insulating liquids and gases appeared on the market. The growing number of transformers filled with alternative insulating liquids has led to the development of new standards for three alternative insulating liquid types: Silicone, High Molecular Weight Hydrocarbon, and Ester based. However, many existing standards in the Transformer Committee’s domain acknowledge only mineral oil. Furthermore, even the mineral oil terms are not consistent within the C57 standardsseries and often within clauses of a same standard. Thus, the SC of Standards sponsored a Task Forceto explore recommendations for standardization of terms related to insulating liquids.
The White Paper Task Force
In order to assure that the recommendations were reached from each technical specialty in a collaborative manner, Task Force volunteers were sought from the SC of Insulating Fluids, the SC of Standards, and most importantly, from the Working Groups (WG) involved in the standard-making process within each SC. The following individuals volunteered to help in this project.
William Bartley / Jagdish BurdeDonald Cherry / David Hanson
David Harris, Vice Chair / William Henning
Stephen Shull, Secretary / John Luksich
Susan McNelly / Patrick McShane, Chair
Jerry Murphy / Nicholas Perjanik
Jerry Reeves / David Sundin
Classification of Issues and Areas in Need of Review
The White Paper Task Forceidentified five types of issues that were in need of consideration during the review and recommendation processes. The five types of frequently recurring issues are listed below.
1.Omissions of various alternative insulating liquids in existing clauses even though inclusion is technically valid
Example 1a: The following standard only mentions mineral oil in its Scope: IEEE Std C57.12.34™-2004, IEEE Standard Requirements for Pad-Mounted, Compartmental-Type, Self-Cooled, Three-Phase Distribution Transformers (2500 kVA and Smaller)─“This standard covers certain electrical, dimensional, and mechanical characteristics and takes into consideration certain safety features of three-phase, 60 Hz, mineral-oil-immersed, …”Because this standard covers liquid insulated pad-mounted transformers in general, it needs to reflect that in its Scope.
Solution: Change the wording from “mineral-oil-insulated” to “insulating liquid immersed.”
Example 1b:Standard C57.12.20 for Overhead Transformers 500 kVA and Smaller… has a clause in Section 3.2 on page 2, which states: “The complete transformer housing, tank, cover, band, etc., that contains the oil, the core and coil, the accessories, etc.,”. Because alternative insulating liquids are used in transformers covered by this standard, it should reflect that as appropriated throughout.
Solution: Change the wording from “oil” to “insulating liquids.”However, if the SC responsible for this standard determines that the standard is only suitable for mineral oil filled units then at a minimum the word “mineral” should be added before the word “oil.”
2.Clauses where generic oil terms are used but should be limited to certain insulating liquid(s) for technical reasons
Example:IEEE Std C57.106: IEEE Guide for Acceptance and Maintenance of Insulating Oil in Equipment standard is currently limited to Type I and Type II mineral oils.Also, there are specific DGA Guides and WGs for certain alternative fluids. There appears to be a consensus to establish a generic term for all liquid dielectric coolants:“insulating liquid(s).”
Solution:The word “Mineral” should be inserted before the word “Oil” in the title.Thus, the wording should be “mineral oil insulating liquid,” at least in the title, scope,
purpose, and introduction of the standard. Thereafter, a shortened version or acronym should be used. For example, “mineral oil insulating liquid,” hereafter referred to as “mineral oil.”
3.Clauses where revisions may be necessary based on different technical properties of insulating liquids
Example: IEEE Std. 62 (no longer an active standard) had recommended power factor limits for new and functioning transformers based on mineral oil as the dielectric liquid. However, the overall power factor of a new and operating transformerwith alternative insulating liquids (all other variables being equal) could change the initial liquid dissipation values. Therefore, the limit values for the overall power factor of a transformer may beinfluenced by the type of insulating liquid used in the unit.
4.Clauses where the same insulating liquid type is referred to with different nomenclatures
Examples:
- Generic: Oil, Insulating Oil, Insulating Fluid, Transformer Oil, Dielectric Coolant
Preferred: Insulating Liquid
- Conventional Mineral Oil: Oil, Insulating Oil, Mineral Oil, Transformer Oil
Preferred: Mineral Oil
- Alternative Insulating Liquids:
- Natural Ester: Natural Ester, Vegetable Oil, Natural Ester Fluid, Biodegradable Fluid.
Preferred: Natural Ester
- Synthetic Ester: Synthetic Ester, Polyol Ester, Pentaerythritol Esters
Preferred: Synthetic Ester
- High Molecular Weight Hydrocarbon: HMWH, High Fire Point Hydrocarbon, Less-flammable Hydrocarbon, High Fire-Point Mineral Insulating Oil (ASTM)
Preferred: High Molecular Weight Hydrocarbon (HMWH)
- Dimethyl Siloxane: Silicone Fluid, Synthetic Oil, Silicone Oil, 50 cSt silicone, PDMS
Preferred: Silicone Liquid
5.Clauses where different terms are being used interchangeably
Examples:
- Fluid Filled, Fluid-Filled, Liquid Filled, Liquid-Filled, Liquid Immersed, Liquid-Immersed
Preferred: Liquid Immersed
- Insulating Liquids, Insulating Fluids, Insulating Oils
Preferred: Insulating Liquids
- Alternative Fluids,Synthetic Insulating Liquids, Synthetic Oils, PCB Substitutes, High Fire Point Fluids
Preferred: Alternative Insulating Liquids
Additional Guidance for Reviewing Standards for Insulating Liquid Term Normalization.
The Task Forceanticipates that these recommendations will be carefully considered for future revisions of existing standards and as a base for new standards that refer toinsulating liquids. It is recommended that when WGs are formed for standards revision, a Task Force formed not only to review the wording for insulating liquid terms, but other terms as well. This white paper should be used by the Working Groups for guidance on the insulating liquid related terms.
A suggested template for reviewing an existing standard undergoing revision with example standards review can be found in Annex B. While most standards have very few occurrences related to insulating liquids, some have many, such as the example shown in the annex for the recent revision of C57.152 which contained over 150 items for revision.
If you need further help in the use of insulating liquids terms and their applicability in transformer applications, please contact the Insulating Fluids Sub-Committee Chair.
Acknowledgements
The Task Forcewishes to express its gratitude to all who contributed to this White Paper and especially to the officers of the SC Standards and SC Insulating Fluids. Without their contributions, this White Paper would not have been possible. A special thanks to the Task Force officers below and the active Task Force Members.
Chair / Patrick McShaneVice Chair / Dave Harris
Secretary / Steve Shull
Standards Sub-Committee Coordinator / Jerry Murphy
Insulating Fluids Sub-Committee Coordinator / Sue McNelly
Chemical & Material Technical Consultant / Dave Hanson
Power Transformer Technical Consultant / Dave Harris
Distribution Transformer Technical Consultant / Jerry Corkran
ANNEX A – General Definitions
alternative transformer liquids: Insulating liquids,akadielectric coolants, that arebased on sources other than conventional naphthenic petroleum-based mineral oil.
high molecular weight hydrocarbon: An insulating liquid which base is comprised of a high molecular weight hydrocarbon (HMWH) mineral oil, typically with a fire point above 300ºC. For details, please refer to: IEEE Guide for Acceptance and Maintenance of Less-Flammable Hydrocarbon Fluid in Transformers, C57.121.
high oleic based natural ester insulating liquid:An insulating liquid which base is comprised of a natural ester liquid having a high (greater than 75%) oleic acid (monounsaturated fatty acid, C 18:1) level composition, most commonly derived from food grade based triglycerides such as high oleic sunflower seeds.
insulating fluid: Insulating fluids comprised of bases that are either liquid or gas.
insulating liquid: Insulating fluid that remains in the liquid state at normal operating temperatures.
key gases: Gases generated in insulating liquid immersed transformers that can be used for qualitative determination of fault types, based on which gases are typical or predominant at various temperatures.
liquid-immersed transformer: Transformer with a dielectric coolant that are liquid at normal operating temperatures, also referred to as liquid filled transformers.
natural ester insulating liquid: Natural ester insulating liquids are derived from an animal or agricultural (vegetable or seed) source, most commonly food-grade seed based triglycerides such as soy beans.
silicone fluid: An synthetic insulating liquid comprising of polydimethyl siloxanes, typically with a fire point above 300ºC.
synthetic ester insulating liquid: The synthetic ester based insulating liquid, produced by a reaction typically from the combination of an organic acid and an alcohol such as pentaerythritol.
synthetic hydrocarbon oil:An insulating liquid consisting of hydrocarbon compounds that are artificially made (synthesized), often from chemically modified petroleum components rather than whole crude oil, but can also be synthesizedfrom other raw materials.
1 / Recommendations to the IEEE Transformer Committee (TC) on Recommended Changes, Deletions, and Insertions Related to Normalizing the References of Insulating Liquids Throughout the IEEE TC Standard Series.ANNEX B – Examples of Recommended Changes
IEEE Std. C57.12.00 -2010 IEEE Standard for General Requirements for Liquid Immersed Distribution, Power and Regulating TransformersPage / Section and/or Line / Current wording / Recommended wording
CL4.2 / line 9 / (such as cables…..tap changers, oil expansion space etc.) / (such as cables…..tap changers, liquid expansion space etc.)
CL6.6.1 / b / Less flammable hydrocarbon fluid / Less flammable hydrocarbon insulating liquid
c / Silicone fluid / Silicone insulatingliquid
pg33 NOTE3 / silicone insulating fluid / silicone insulating liquid
CL7.3.5 / a / Gas generation from oil or solid insulation… / Gas generation from liquid or solid ….
Table 18 / Tests
pg48 / Dissolved gas in oil analysis / Dissolved gas in insulating liquid analysis. or
as a minimum, Dissolved gas in liquid analysis…
CL8.7 b 8 / pg51 / Insulating medium (oil,….) / Insulating liquid
CL8.7 c6iii / pg52 / oil flow in winding / insulating liquid flow in winding
CL8.7 c6iv / final bottom and top oil temp / final bottom and top insulating liquid temp
IEEE Std. C57.12.10 -2010 IEEE Standard Requirements for Liquid Immersed Power Transformers
Page / Section and/or Line / Current wording / Recommended wording
CL4.2.1 / line 2 / temp rise of insulating fluid…… / temp rise of insulating liquid……
CL5.1.3 / line6 / ….so that it is covered by at least 2.5cm of fluid….at lowest …fluid level / ….so that it is covered by at least 2.5cm of liquid….at lowest …liquid level
CL5.1.4 / pg11 / when a top fluid… / when a top liquid…
para3, lines1, 4 / is covered by…of fluid….at lowest permissible fluid… / is covered by…of liquid….at lowest permissible liquid…
CL5.1.8 / line2 / for drainage of liquid…. / for drainage of liquid….
CL5.1.9 / line3 / gas space mounted …under fluid relay. Under fluid relay… / gas space mounted …under liquid relay. Under liquid relay…
CL5.3.3.1 / line5 / with or without oil…… / with or without liquid
CL5.3.4 / NOTE4 pg17 / weight includes complete…. And fluid / weight includes complete…. And fluid
CL5.7.3 / line2 / seals the oil in main tank…. / seals the insulating liquid in main tank…
line3 / the internal top oil pressure… / the internal top liquid pressure…
CL5.7.3.3 / pg20 / Liquid level indicator / Liquid level indicator
CL5.7.3.4 / line3 / and is provided with an oil trap…. / and is provided with a liquid trap…
CL5.9.3 / line3 / with minimum loss of insulating oil. / with minimum loss of insulating liquid
NOTE line2 / specified fluid properties.. / Specified insulatingliquid properties
CL6.2.2 d / pg28 / on side of each oil filled compartment / on side of each liquid-filled compartment
IEEE Std. PC57. 152 D5.0 Guide for Diagnostic Field Testing of Electric Power Apparatus- Part 1: Oil Filled Power Transformers, Regulators, and Reactors v.3.5.12 CPM
Page / Section and/or Line / Current wording / Recommended wording
ii / Line 23 / ...on fluid filled power... / ...on liquid filled power...
ii / Line 34 / Fluid filled transformers, / Liquid filled transformers,
ii / Line 34 / , insulating fluids, / Add to list: ,"insulating liquid, dielectric coolants,"….
iv / Line 37 / Diagnostic Field Testing of Fluid Filled Transformer / Diagnostic Field Testing of liquid Filled Transformer
vii / Line 201 / Insulating fluid / Insulating liquid
1 / Line 350 / …on fluid filled power… / …on liquid filled power..
4 / Table 5 -Main / Oil Quality Tests and DGA / Insulating Liquid Quality Tests and DGA
4 / Table 5 -LTC / Oil Quality Tests and DGA / Insulating Liquid Quality Tests and DGA
4 / Line 476 / ...maintence practice – Oil quality,… / ...maintence practice – insulating liquid quality,…
7 / Line 607 / ...draining it of oil is not… ...without all the oil removed,… / ...draining it of insulating liquid is not… ...without all the insulating liquid removed,…
7 / Line 608 / ...possibility of falling into the oil. / ...possibility of falling into the insulating liquid.
10 / Line 702 / Oil temperature, winding…. / Insulating liquid temperature, winding….
10 / Line 704 / Oil levels of the main tank and all oil-filled compartments / Liquid levels of the main tank and all insulating liquid-filled compartments
10 / Line 714 / Cooling fans and oil circulating pumps,…. / Cooling fans and insulating liquid circulating pumps, …
10 / Line 720 / ...for signs of oil leakage. / ...for signs of insulating liquid leakage.
10 / Line 721 / ….and repair any oil leaks. / ….and repair any insulating liquid leaks.
11 / Line 731 / ...for cracks, dirt, oil leaks,... / ...for cracks, dirt, insulating liquid leaks,...
11 / Line 743 / ...conservator, or oil preservation system,…. / ...conservator, or insulating liquid preservation system,….
11 / Line 744 / ...check for oil leakage into the bladder. / ...check for insulating liquid leakage into the bladder.
11 / Line 751 / ...cooling, low oil level, low gas… / ...cooling, low liquid level, low gas…
12 / Line 769 / This positioning allows the oil in... / This positioning allows the insulating liquid in...
12 / Line 771 / ….and an oil level indicator / ….and a liquid level indicator
12 / Line 772 / ...for the tank’s oil as… / ...for the insulating liquid of the tank as…
IEEE Std. PC57. 152 D5.0 Guide for Diagnostic Field Testing of Electric Power Apparatus- Part 1: Oil Filled Power Transformers, Regulators, and Reactors v.3.5.12 CPM
12 / Line 773 / ….expansion vessel for the tank’s oil. / ….expansion vessel for the insulating liquid of the tank.
12 / Line 775 / The oil level rises and falls …………, and the oil is… / The insulating liquid level rises and falls………... , and the insulating liquid is…
12 / Line 777 / ….prevent the oil from coming in…. / ….prevent the insulating liquid from coming in….
12 / Line 779 / As the oil level in the conservator….. / As the insulating liquid level in the conservator…..
12 / Line 781 / ….expansion of the equipment’s oil. / ….expansion of the equipment’s insulating liquid.
12 / Line 783 / The oil level indicated on the liquid level guage... / The insulating liquid level indicated on the liquid level guage...
12 / Line 784 / ….gauge. The top oil temperature / ….gauge. The top insulating liquid temperature
12 / Line 785 / The top oil temperature reading….. / The top insulating temperature temperature reading…..
12 / Line 786 / ...correct the oil level gauge reading. / ...correct the liquid level gauge reading.
12 / Line 790 / ...the equipment’s oil. / …the insulating liquid of the equipment.
12 / Line 792 / ...unless there is an oil leak, etc. / ...unless there is an insulating liquid leak, etc.
12 / Line 793 / Oil sampling for diagnostic / Insulating liquid sampling for diagnostic
12 / Line 794 / Otherwise, oil should never be added … / Otherwise, insulating liquid should never be added …
12 / Line 801 / ...during the final oil filling stage. / ...during the final insulating liquid filling stage.
13 / Line 823 / Insulating fluid / Insulating liquid
13 / Line 825 / The insulating fluids / The insulating liquids
13 / Lines 829-830 / ...mineral oil and less flammable hydrocarbon, and natural and sythetic ester / ...mineral oil and less-flammable hydrocarbon, and natural and sythetic ester
insulating fluids and the diagnosis of power equipment based / ester insulating fluids and the diagnosis of power equipment based
on fluid condition [B2–B5]. / on the condition of the insulating liquid [B2–B5].