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BIOTEMP is a registered trademark of ABB Inc.
©Copyright 2011 ABB, All rights reserved.
1LAB000385 – en, rev. 0 March 2011
BIOTEMP® dielectric insulating fluid Handling and operational instructions manual
1 Scope and application ............................................................................................................................... 3 2 Introduction to BIOTEMP ........................................................................................................................... 3
2.1 General description .............................................................................................................................. 3 2.2 Typical performance characteristics ..................................................................................................... 3 2.3 Sensitivity to moisture .......................................................................................................................... 3 2.4 Sensitivity to oxidation .......................................................................................................................... 4
3 Fluid handling and storage instructions .................................................................................................. 5 3.1 Safety issues ........................................................................................................................................ 5 3.2 Static charge ........................................................................................................................................ 6 3.3 Air exposure ......................................................................................................................................... 6 3.4 Low temperature storage and handling ................................................................................................ 6 3.5 Material compatibility ............................................................................................................................ 6
4 Fluid treatment process ............................................................................................................................. 6 4.1 Fluid requirements prior to filling .......................................................................................................... 7 4.2 Fluid testing requirements .................................................................................................................... 8
5 Insulation drying and impregnation ......................................................................................................... 8 6 Labeling of transformers filled with BIOTEMP ........................................................................................ 9 7 Other resources ........................................................................................................................................ 10
Disclaimer of warranties and limitations of liability
The information, recommendations, descriptions and safety notions in this document are based on tests performed by ABB, third party laboratories, and from documents in the public domain with respect to BIOTEMP® use in transformers. This information should not be considered to be all inclusive or covering all contingencies. No warranties, expressed or implied, including warranties of fitness for a particular purpose or merchantability, or warranties arising from course of dealing or usage of trade, are made regarding the information, recommendations, descriptions, and safety notations contained herein. In no event will ABB be responsible to the user in contract, in tort (including negligence), strict liability, or otherwise for any special, indirect, incidental, or consequential damage or loss whatsoever. This includes, but is not limited to, damage to or loss of use of equipment, plant or power system, cost of capital, loss of profits or revenues, cost of replacement power, additional expenses in the use of existing power facilities, or claims against the use by its customers resulting from the use of the information, recommendations, descriptions, and safety notations contained herein.
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1 Scope and application This document describes the treatment process and testing procedure of ABB natural ester dielectric insulating fluid, BIOTEMP®, before it can be used to fill transformers. It also gives handling and storage instructions in transformer manufacturing facilities.
2 Introduction to BIOTEMP
2.1 General description BIOTEMP is a biodegradable, high fire point, natural ester (i.e., vegetable based) dielectric coolant. It was developed to deliver an environmentally safe fluid with a high margin of fire safety. It is miscible with conventional transformer oils1 (i.e., mineral based oils) and compatible with standard transformer materials. BIOTEMP can be used in many applications where its unique environmental, safety and performance properties are an advantage.
2.2 Typical performance characteristics BIOTEMP typical performance characteristics are listed in Table 1 below and compared to other currently used insulating fluids, such as mineral oil, synthetic ester, high temperature hydrocarbon (HTH), and silicone fluid.
2.3 Sensitivity to moisture BIOTEMP absorbs moisture at a more rapid rate than petroleum based fluids. However, it can both tolerate and dissolve much more moisture than can petroleum based insulating fluids. Moisture is soluble in BIOTEMP up to 1,100 ppm at room temperature. Levels of moisture up to 500 ppm or 45% RH do not reduce the dielectric strength to unacceptable levels (see Figure 1). Moisture at this level does not result in the formation of a separate water (ice) layer.
High moisture levels (above 500 ppm or 45% RH) or free moisture can have a negative effect on both the electrical and chemical properties of BIOTEMP and is to be avoided. Moisture level determinations can be performed using the same equipment and testing techniques as used with all other hydrocarbon based dielectric fluids. Moisture can be readily removed, with or without heating, by any of a variety of commonly utilized vacuum processing techniques.
When maintained in sealed equipment in the absence of dissolved contaminants and free water, BIOTEMP will not form fungal or other biological growths. However, under extended warm conditions and in the presence of contaminants that can act as food materials for fungi, free moisture may lead to biological growths in the unit. As with any other dielectric fluids, special care must be taken to keep units containing BIOTEMP free of excessive moisture and contaminants.
1 BIOTEMP mixes in all proportions with mineral oils but does not mix in any proportions with silicone fluids.
Concentrations of mineral oil in excess of 7% by weight may however lower its fire point below 300°C.
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Table 1 – Typical dielectric insulating fluids properties.
Property Mineral oil
BIOTEMP Synthetic ester
Silicone fluid
High Temp Hydrocarbon
Specific gravity (g/ml) 0.90 0.91 0.97 0.96 0.87
Viscosity (cSt) at 100°C 2 9 5 15 12
at 40°C 9 42 28 50 113
Thermal conductivity (W/mK) at 25°C
0.14
0.17
0.14
0.15
0.13
Breakdown strength (kV) (ASTM D 1816, 2-mm gap or *IEC 60156, 2.5-mm gap)
>70* 76 >75* 50* 56
Power factor (%) at 25°C (ASTM D 974 or IEC 60247)
0.001 0.09 0.10 < 0.01 0.01
Permittivity (-) at 25°C (ASTM D 924 or IEC 60247)
2.2 3.2 3.2 2.7 2.2
Biodegradability (%) (CEC L-33-A-93)
25 99 80 5 20
Flash point (°C) 150 314 275 > 300 276
Fire point (°C) 160 347 322 > 340 312
Pour point2 (°C) -50 -15 -60 -55 -24
2.4 Sensitivity to oxidation BIOTEMP is provided with oxidation inhibitors. The same inhibitors are used in many other types of consumer products and are not considered toxic to humans at the levels present in the fluid. These inhibitors provide sufficient protection to keep the fluid from premature oxidation in electrical equipment. The inhibitor package is present in a very low concentration and requires special analytical equipment and techniques to determine the remaining protective life of the inhibitors.
BIOTEMP can be oxidized and oxygen will start degrading BIOTEMP once the oxidation inhibitor is consumed. BIOTEMP is however supplied with sufficient oxidation inhibitor to pass the ASTM D 2440 oxidation stability test. During a normal expected life time of a unit, the oxidation inhibitors in the fluid should provide more than enough protection from oxidative degradation. It is also worth noting that, due to its very high percentage of oleic acid (> 75%), BIOTEMP is by nature more resistant to oxidation over time than all other natural ester-based fluids currently available on the market. We recommend however shipping units filled with BIOTEMP under a dry nitrogen blanket in the headspace.
2 BIOTEMP does not contract upon freezing and solidifies into a hard gel-like solid that still acts as both an insulating
and cooling medium. In transformers, gas evolution from rapidly cooled BIOTEMP has not been observed.
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Figure 1 – BIOTEMP dielectric breakdown voltage as a function of moisture content (unfiltered).
In these conditions and unless the fluid is left exposed to air for several hours without degassing before prolonged operation, no excessive oxidation should occur.
Degassing and refilling the headspace with dry nitrogen after prolonged or frequent exposure (totaling more than five (5) hours) to air is recommended and will extend the life of the fluid.
3 Fluid handling and storage instructions BIOTEMP can be transferred and stored in a manner similar to petroleum based fluids. Transfer equipment and storage vessels should be clean and free of contaminates and moisture3. During storage the vessel should be airtight and preferably BIOTEMP should be stored under dry nitrogen. It is preferred that bulk storage tanks be located indoors. Outdoor storage tanks will need to be insulated and heated to maintain a fluid temperature of 10°C (50°F) for optimum pumping efficiency. BIOTEMP is not an aggressive solvent and is not known to degrade rubber hoses or membranes.
3.1 Safety issues BIOTEMP is nontoxic. It rapidly degrades in soil or water if microbes are present.
3 Certain detergents, solvents and chemical agents used in the manufacturing process can adversely affect the electrical
properties of the insulating liquid. Every effort must be taken to ensure that all residues of these products are completely removed prior to introducing BIOTEMP.
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BIOTEMP should not be considered as an edible material due to the oxidation inhibitors added and to the contaminants introduced when the fluid is used in electrical equipment.
BIOTEMP is listed as a “less flammable” insulating fluid (fire point 300°C) and meets the IEC K fire hazard class.
Releases of BIOTEMP will result in slippery and hazardous work surfaces. Clean up of such surfaces can be accomplished with the same materials and techniques as used for other oil spills.
Do not dispose of BIOTEMP by improper release into the environment. Although BIOTEMP is a nontoxic material, large quantity releases into the environment could have a negative environmental impact.
3.2 Static charge As with other dielectric fluids, flowing BIOTEMP fluid can produce a significant high voltage static charge during pumping operations. It is recommended that all equipment, winding leads, containers and piping be grounded during pumping.
3.3 Air exposure To maintain the optimal fluid properties as a dielectric insulating fluid, exposure of BIOTEMP to oxygen, moisture and other contaminants must be minimized. Except for short periods of time, material that has been immersed in BIOTEMP fluid should not be exposed to air. Thin films of natural ester fluids tend to polymerize in the presence of oxygen over time. It is however again worth noting that BIOTEMP is by nature (> 75% of high oleic acid content) more resistant to oxidation than all other natural ester-based fluids currently available on the market and that consequently the risk of early polymerization or thin film formation is greatly mitigated.
3.4 Low temperature storage and handling Prolonged storage at -5°C (23°F) will cause BIOTEMP fluid to freeze into a gel. Prior to pumping, the fluid must be warmed to above 10°C (50°F) in order to efficiently transfer the fluid by pump. For outdoor pumping in cold weather, pipes should be heated with steam coils or electric resistance heat tracing. A means of keeping BIOTEMP above 10°C (50°F) is needed for ease of handling.
3.5 Material compatibility BIOTEMP is compatible with most materials used in conjunction with conventional electrical grade mineral oil. Compatibility should however be verified for each new application.
4 Fluid treatment process Before the received transformer fluid can be used in transformers, it must be cleaned further via a filtering system to obtain required quality.
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The filtering system consists of a strainer, a heater, a 5- m particle filter, a degasser and a vacuum pump.
Figure 2 – Fluid treatment system.
Each fluid should have a separate treatment system and filling hoses to avoid intermixture and contamination of the fluids4.
Also all gaskets materials should be compatible with BIOTEMP. Fluorosilicone and high grade nitrile rubbers have been found to be compatible with BIOTEMP.
For some examples of fluid treatment systems, see5:
CJC Oil Filtration (www.cjc.dk)
Europafilter (www.europafilter.se)
Enervac Corporation (www.enervac.com)
FilterVac International (www.filtervac.com)
Baron Transformer Oil Purifiers (www.baronusa.com)
4.1 Fluid requirements prior to filling BIOTEMP typical requirements prior to filling are listed in Table 2 below and compared to other currently used insulating fluids, such as mineral oil, synthetic ester and silicone fluid.
4 BIOTEMP is miscible and compatible with mineral oils. However, avoid contamination of BIOTEMP with conventional
transformer oil to prevent lowering its flash and fire points, and for possible environmental regulations purposes. Article 450-23 of the US National Electric Code (NEC) requires a minimum ASTM D 92 fire point of 300°C for “less flammable” transformer liquids. The maximum percent mineral oil contamination in BIOTEMP to maintain its fire point above 300°C is 7%. Dedicated equipment is the preferred means to avoid contamination. Otherwise, it is recommended to flush the equipment with an appropriate volume of at least 5% BIOTEMP. This oil is then to be discarded after the flushing.
5 Contact listed vendors directly for current quotes.
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Table 2 – Fluid requirements prior to filling
Mineral oil BIOTEMP Synthetic ester
Silicone fluid
Fluid temperature (°C) 50-60 60-80 60-80 60-80
Water content (ppm) 15 100 100 50
Breakdown voltage (kV) 30 45 45 40
Particle size ( m) 5 5 5 5
4.2 Fluid testing requirements All ASTM D 6871 prescribed tests as well as most other evaluative tests can be performed on BIOTEMP without any special equipment or reagents. Equipment and vessels must simply be readily cleaned using common solvents such as acetone, low molecular weight hydrocarbons, or mineral spirits. The ability of BIOTEMP to absorb moisture and gasses more rapidly than petroleum based fluids requires good laboratory techniques to attain accurate sample preparation and storage.
The water content should be tested in accordance with the ASTM D 1533 or IEC 60814 standard method6.
The breakdown voltage should be tested in accordance with the ASTM D 1816 (2-mm gap) or IEC 60156 (2.5-mm gap) standard method.
5 Insulation drying and impregnation There are a number of different approaches or processes that can be employed for the purposes of drying the insulation materials prior to impregnation with BIOTEMP. Hot Air drying, low frequency heating or hot solvent drying are all methods that can be employed to remove the maximum amount of moisture before introducing the fluid, preferably under vacuum. Refer to the specific drying equipment manufacturers instructions for the recommended set points and process conditions.
It is recommended to allow BIOTEMP-filled transformers to stand at least several hours after filling and vacuum breaking or until the transformer has cooled to room temperature before energizing or high-voltage testing. BIOTEMP fluid generally takes significantly longer to impregnate cellulose insulation than mineral oil under the same conditions. Transformers with heavy thicknesses of pressboard insulation will require standing times that are adequate to allow the required impregnation. The impregnation rate of BIOTEMP is a function of the fluid temperature and viscosity as well as of the thickness of the cellulose material to be saturated.
6 As stated in Test Methods ASTM D 1533 Annex A1 “Alternative Solvent Systems,” alternate reagents may be needed
for certain natural ester formulations. Consult the manufacturer for recommendations. Reagents for aldehydes and ketones (such as Coulomat AK and CG-K) should be used if the additives are unknown. When alternate reagents are needed, using the Test Methods ASTM D 1533 reagents may yield elevated and erratic water content results.
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Figure 3 – BIOTEMP and mineral oil viscosity as a function of temperature.
The recommended minimum standing times will vary depending on the type of pressboard, thickness, initial fluid temperature, ambient temperature, voltage class, etc. Impregnation times with BIOTEMP should in general be increased by at least 50% over the standard times used for mineral oil applications at the same temperature in small distribution transformers and up to about 3 times in larger power transformers. However, experimentation has shown that BIOTEMP at 60°C is similar to mineral oil at 20°C with respect to viscosity and capillary action which directly effects impregnation of the solid insulation materials.
Figure 3 compares the viscosity curves of mineral oil and BIOTEMP as a function of temperature. As an example the viscosity of BIOTEMP at 100°C is equivalent to mineral oil at 50°C. Such viscosity matching can be used to select an impregnation temperature to match the same impregnation time as mineral oil. However, it is not recommended that BIOTEMP be heated above 140°C to prevent scorching the fluid. Refer to the transformer and/or insulating paper/pressboard manufacturers for guidance concerning impregnation rates.
6 Labeling of transformers filled with BIOTEMP It is recommended that the transformer be labeled as to the exact fluid content. This can serve to prevent mixing or cross contaminating BIOTEMP with other fluids. ABB does have labels that are designed for that purpose and that can be provided upon request.
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7 Other resources 1. ASTM D 6871-03 (2008), Standard Specification for Natural (Vegetable Oil) Ester Fluids
Used in Electrical Apparatus, August 2003 (reapproved in October 2008)
2. IEEE C57.147, IEEE Guide for Acceptance and Maintenance of Natural Ester Fluids in Transformers, July 2008
3. Brazilian Standards Association – PROJETO 03:010.02-027, Natural Vegetable Oils for Electrical Equipment, May 2005
4. CIGRE Brochure 436, Experiences in Service with New Insulating Liquids, October 2010.
©Copyright 2011 ABB, All rights reserved
Document Title
BIOTEMP® dielectric insulating fluid Document No. – Lang. – Rev. Date No. of Pages Page
1LAB000385 – en – 0 March 2011 11 11
For more information, contact us:
ABB Inc. 1128 South Cavalier Drive Alamo, Tennessee, 38001-3813 United States Phone: +1 731 696 5235 Fax: +1 731 696 5269 E-Mail: [email protected]
www.abb.com/transformercomponents
We reserve the right to make technical changes or modify the contents of this document without prior notice. With regard to purchase orders, the agreed particulars shall prevail. ABB does not accept any responsibility whatsoever for potential errors or possible lack of information in this document. We reserve all rights in this document and in the subject matter and illustrations contained therein. Any reproduction – in whole or in parts – is forbidden without ABB’s prior written consent.
