IEC 60156:2025 specifies the method for determining the dielectric breakdown voltage of insulating liquids at power frequency. The test procedure is performed in a specified apparatus, where the oil sample is subjected to an increasing AC electrical field until breakdown occurs. The method applies to all types of insulating liquids of nominal viscosity up to 350 mm2/s at 40 °C. It is appropriate both for acceptance testing on unused liquids at the time of their delivery and for establishing the condition of samples taken in monitoring and maintenance of equipment.

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IEC 62770:2024 describes specifications and test methods for unused natural esters in transformers and similar liquid-immersed electrical equipment in which a liquid is required as an insulating and heat transfer medium. The exposure of natural ester to air leads to deterioration of the insulating liquid. Use of natural esters is therefore restricted to sealed units, or with the conservator tank protected from the contact with atmosphere by a membrane or other suitable system.

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IEC 62770:2024 describes specifications and test methods for unused natural esters in transformers and similar liquid-immersed electrical equipment in which a liquid is required as an insulating and heat transfer medium. The exposure of natural ester to air leads to deterioration of the insulating liquid. Use of natural esters is therefore restricted to sealed units, or with the conservator tank protected from the contact with atmosphere by a membrane or other suitable system.

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IEC 62770:2024 describes specifications and test methods for unused natural esters in transformers and similar liquid-immersed electrical equipment in which a liquid is required as an insulating and heat transfer medium. The exposure of natural ester to air leads to deterioration of the insulating liquid. Use of natural esters is therefore restricted to sealed units, or with the conservator tank protected from the contact with atmosphere by a membrane or other suitable system.

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IEC 63177:2024 specifies the test method for the compatibility of construction materials with electrical insulating liquids for use in electrical equipment, such as liquid-immersed transformers and tap-changers, liquid-impregnated capacitors, and liquid-cooled rotating machines used in electrical vehicles and oil pumps. This document is applicable to mineral insulating liquids, natural esters, silicone insulating liquids, synthetic organic esters, modified esters, capacitor fluids based on synthetic aromatic hydrocarbons and e-transmission fluids used in electrical vehicles and oil pumps. The compatibility tests are not sufficient for a full qualification of construction materials for a given application without additional tests requested by the appropriate IEC Technical Committee or equipment manufacturers.

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This document is applicable to the sampling procedure used for insulating liquids in delivery containers and in electrical equipment such as power and instrument transformers, reactors, bushings, oil-filled cables, oil-filled tank-type capacitors, switchgear and load tap changers (LTCs).
This document applies to liquids the viscosity of which at the sampling temperature is less than 1 500 mm2/s (or cSt). It applies to mineral oils and non-mineral oils (such as synthetic esters, natural esters, vegetable oils or silicones).

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IEC 60312:2019 defines requirements for the characterization of unused modified esters or blends of unused esters used as insulating liquids for electrotechnical applications. It does not cover liquids that contain any proportion of used liquids. The liquids covered by this document are intended mainly for transformer applications.
Unused modified/synthetized esters are derived from a natural or synthetic base, or are blends of both. This document covers a variety of ester liquids not covered by other standards specific to natural esters (IEC 62770) or synthetic esters (IEC 61099). As it addresses various categories of liquids, this document also covers a wide range of values for certain performance characteristics. An important property is viscosity, which can affect the design and cooling performance of electrical equipment. A categorization is defined based on the kinematic viscosity of the different liquids. The category of low viscosity ester liquids is established.

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IEC 62961:2018 establishes the measurement of the interfacial tension between insulating liquid and water by means of the Du Noüy ring method close to equilibrium conditions. In order to obtain a value that provides a realistic expression of the real interfacial tension, a measurement after a surface age of approximately 180 s is recorded.

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IEC 62820-3-1:2017 gives guidelines for planning, installation, commissioning, operation and maintenance of Building Intercom Systems (BIS), for use in security applications. The different technical requirements for BIS are specified in IEC 62820-1-1 and IEC 62820-1-2. The objectives of this document are to:
- provide a framework to assist system integrators, installers, consultant engineers and system owners in establishing their requirements;
- assist specifiers and system owners in determining the appropriate equipment required for a given application.

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IEC 60836:2015 covers specifications and test methods for unused silicone liquids intended for use in transformers and other electrotechnical equipment. Besides the standard transformer applications there are other applications of silicone liquids, such like cable accessories, capacitors, electrical magnets etc.
This edition includes the following major technical changes with regard to the second edition:
a) classification of liquids according to IEC 61039 have been adapted with respect to the latest edition of IEC 61039:2008;
b) classification of liquids according to IEC 61100:1992 have been removed as IEC 61100 has been withdrawn;
c) minimum requirements for other silicone liquids for electrotechnical purposes have been added.

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IEC 62770:2013 describes specifications and test methods for unused natural esters in transformers and similar oil-impregnated electrical equipment in which a liquid is required as an insulating and heat transfer medium. Natural esters with additives are within the scope of this standard. Because of their different chemical composition, natural esters differ from insulating mineral oils and other insulating fluids that have high fire points, such as synthetic esters or silicone fluids. Natural, ester-derived insulating fluids with low viscosity have been introduced but are not covered by this standard. Pertinent properties of such fluids are given in Annex B. This standard is applicable only to unused natural esters. Reclaimed natural esters and natural esters blended with non-natural esters fluids are beyond the scope of this standard.

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Provides guidance on the minimization of fire hazard arising from the use of electrical insulating liquids to a) electrotechnical equipment and systems, b) people, building structures and their contents. As insulating liquids are always part of an insulating system, the fire hazard of the complete system must also be assessed. Has the status of a basic safety publication in accordance with IEC Guide 104.

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IEC 62770:2013 describes specifications and test methods for unused natural esters in transformers and similar oil-impregnated electrical equipment in which a liquid is required as an insulating and heat transfer medium. Natural esters with additives are within the scope of this standard. Because of their different chemical composition, natural esters differ from insulating mineral oils and other insulating fluids that have high fire points, such as synthetic esters or silicone fluids. Natural, ester-derived insulating fluids with low viscosity have been introduced but are not covered by this standard. Pertinent properties of such fluids are given in Annex B. This standard is applicable only to unused natural esters. Reclaimed natural esters and natural esters blended with non-natural esters fluids are beyond the scope of this standard.

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IEC 62697-1:2012 specifies a test method for the quantitative determination of corrosive sulfur compounds-dibenzyl disulfide (DBDS) in used and unused insulating liquids over a 5 to 600 mg kg-1 concentration range.

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IEC 62697-1:2012 specifies a test method for the quantitative determination of corrosive sulfur compounds-dibenzyl disulfide (DBDS) in used and unused insulating liquids over a 5 to 600 mg kg-1 concentration range.

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This International Standard specifies oil-sampling procedures, analysis requirements and procedures, and recommends sensitivity, repeatability and accuracy criteria for the application of dissolved gas analysis (DGA) to factory testing of new power transformers, reactors and instrument transformers filled with mineral insulating oil when DGA testing has been specified. The most effective and useful application of DGA techniques to factory testing is during the performance of long-term tests, typically temperature-rise (heat run) and overloading tests on power transformers and reactors, also impulse tests on instrument transformers. DGA may also be valuable for over-excitation tests run over an extended period of time. Experience with DGA results, before and after short-time dielectric tests, indicates that DGA is normally less sensitive than electrical and acoustic methods for detecting partial discharges. However, DGA will indicate when these partial discharges become harmful to the insulation and may be detected by inspection.

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IEC 61099:2010 covers the specification and test methods for unused synthetic organic esters. It applies to synthetic organic esters, delivered to the agreed point and time of delivery intended, for use in transformers, switchgear and similar related equipment in which synthetic organic esters are required as an insulant and for heat transfer. The main changes of this new edition with respect to the previous one relate to the aim of giving a more updated specification of synthetic organic esters when used as insulating liquids.

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Specifies oil-sampling procedures, analysis requirements and procedures, and recommends sensitivity, repeatability and accuracy criteria for the application of dissolved gas analysis (DGA) to factory testing of new power transformers, reactors and instrument transformers filled with mineral insulating oil when DGA testing has been specified. The most effective and useful application of DGA techniques to factory testing is during the performance of long-term tests, typically temperature-rise (heat run) and overloading tests on power transformers and reactors, also impulse tests on instrument transformers. DGA may also be valuable for over-excitation tests run over an extended period of time. Experience with DGA results, before and after short-time dielectric tests, indicates that DGA is normally less sensitive than electrical and acoustic methods for detecting partial discharges. However, DGA will indicate when these partial discharges become harmful to the insulation and may be detected by inspection [2]. This edition includes the following significant technical changes with respect to the previous edition: a) the specific procedures used during factory tests (sampling location, sampling frequency, gas extraction and chromatographic analysis in the laboratory) are described in more detail;   b) information is provided in Annex A concerning the residual gas contents recommended before thermal tests on power transformers, typical gas values observed during the tests and cases where gas formation during the tests was followed by problems in the transformers; c) typical values observed during chopped lightning-impulse tests on instrument transformers are indicated in Annex B.

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Describes the sampling procedures and methods for the determination of particle concentration and size distribution.  Three methods are specified. One uses an automatic particle size analyser, working on the light interruption principle. The other two use an optical microscope, in either the transmitted light or incident light mode, to count particles collected on the surface of a membrane filter. The optical microscope methods are described in ISO 4407.  All three methods are applicable to both used and unused insulating liquids.  Annex A contains an alternative sampling procedure using a syringe and Annex B reports a reference for the calibration of automatic particle counters. The significant technical changes with respect to the previous edition are as follows: - new calibration procedures for automated laser particle;  - three figures contamination code;  - new procedure of sample pre-treatment when automated laser counter method are used.

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Describes methods for the determination of the dielectric dissipation factor, relative permittivity and d.c. resistivity of any insulating liquid material at the test temperature. The methods are primarily intended for making reference tests on unused liquids. They can also be applied to liquids in service in transformers, cables and other electrical apparatus. However the method is applicable to a single phase liquid only. When it is desired to make routine determinations, simplified procedures, as described in Annex C, may be adopted. With insulating liquids other than hydrocarbons, alternative cleaning procedures may be required. The main changes from the previous edition deal with the preferred measurement method.

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Describes a method for simultaneous measurement of conductance G and capacitance C enabling the calculation of the dielectric dissipation factor tan delta of insulating liquides. Method applies to both unused insulating liquids and insulating liquids in service in transformers and in other electrical equipment.

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Describes a method for simultaneous measurement of conductance G and capacitance C enabling the calculation of the dielectric dissipation factor tan delta of insulating liquides. Method applies to both unused insulating liquids and insulating liquids in service in transformers and in other electrical equipment.

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Describes a method for simultaneous measurement of conductance G and capacitance C enabling the calculation of the dielectric dissipation factor tan delta of insulating liquides. Method applies to both unused insulating liquids and insulating liquids in service in transformers and in other electrical equipment.

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Describes an empirical test procedure intended to indicate the presence of contaminants such as water and solid suspended matter, and the advisability of carrying out drying and filtration treatment. Standardized testing procedures and equipment are essential for the unambiguous interpretation of test results.

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Applies to all insulating liquids, used and unused, the kinematic viscosity of which is lower than or equal to 300 mm2/s at 40 °C.

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IEC 63177:2024 specifies the test method for the compatibility of construction materials with electrical insulating liquids for use in electrical equipment, such as liquid-immersed transformers and tap-changers, liquid-impregnated capacitors, and liquid-cooled rotating machines used in electrical vehicles and oil pumps. This document is applicable to mineral insulating liquids, natural esters, silicone insulating liquids, synthetic organic esters, modified esters, capacitor fluids based on synthetic aromatic hydrocarbons and e-transmission fluids used in electrical vehicles and oil pumps. The compatibility tests are not sufficient for a full qualification of construction materials for a given application without additional tests requested by the appropriate IEC Technical Committee or equipment manufacturers.

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IEC 63177:2024 specifies the test method for the compatibility of construction materials with electrical insulating liquids for use in electrical equipment, such as liquid-immersed transformers and tap-changers, liquid-impregnated capacitors, and liquid-cooled rotating machines used in electrical vehicles and oil pumps. This document is applicable to mineral insulating liquids, natural esters, silicone insulating liquids, synthetic organic esters, modified esters, capacitor fluids based on synthetic aromatic hydrocarbons and e-transmission fluids used in electrical vehicles and oil pumps. The compatibility tests are not sufficient for a full qualification of construction materials for a given application without additional tests requested by the appropriate IEC Technical Committee or equipment manufacturers.

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D145/093: CLC/BTTF 116-1 converted into CLC/TC 10 * D134/030 (taken by majority): BTTF 116-1 to review GB comments in order to either revise draft prepared for vote, or stop project * D135/C151: NWI as CLC/prTR approved (pr=22541)

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Describes a method for measuring the oxygen index of insulating liquids. This test method is applicable to all liquids, the viscosity of which is lower than or equal to 50 mm2/s at 40°C ± 1°C.

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IEC 60475:2011 is applicable to the procedure to be used for insulating liquids in delivery containers and in electrical equipment such as power and instrument transformers, reactors, bushings, oil-filled cables, oil-filled tank-type capacitors, switchgear and load tap changers. The main changes with respect to the previous edition are as follows:  - withdrawal of askarels;  - addition of recommendations concerning general health, safety and environmental protection;  - additional details regarding the sampling of oil from electrical equipment, using various types of sampling devices appropriate for the different types of oil tests to be performed in the laboratory.

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IEC 62701:2014 specifies requirements for recycled mineral insulating oils intended for use in transformers, switchgear, and similar electrical equipment in which oil is required for insulation and heat transfer. These oils are produced by processes employed offsite. Oils treated and reconditioned on-site are not within the scope of this standard. Oils with and without additives are within the scope of this standard. Such oils will have originally been supplied in compliance with a recognized unused mineral insulating oil specification. This standard does not differentiate between the methods used to recycle mineral insulating oil. This standard does not apply to mineral insulating oils used as impregnates in cables or capacitors.

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Specifies analysis requirements and procedures, and recommends sensitivity and precision criteria for factory testing of power transformers, reactors and instrument transformers.

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