IEEE C57.104:1991 pdf download.IEEE Guide for the Interpretation of Gases Generated in Oil-Immersed Transformers.
This guide applies to mineral-oil-immersed transformers and addresses:
1) The theory of combustible gas generation in a transformer
2) The interpretation of gas analysis
3) Suggested operating procedures
4) Various diagnostic techniques, such as key gases, Dornenher ratios, and Rogers ratios
5) Instruments for detecting and determining the amount of combustible gases present
6) A bibliography of related literature
1.2 Limitations
Many techniques for the detection and the measurement of gases have been established. However, it must he recognized that analysis of these gases and interpretation of their significance is at this time not a science, hut an art subject to variability. Their presence and quantity are dependent on equipment variables such as type. location, and temperature of the fault; solubility and degree of saturation of various gases in oil; the type of oil preservation system; the type and rate of oil circulation; the kinds of material in contact with the fault; and finally, variables associated with the sampling and measuring procedures themselves. Because of the variability of acceptable gas limits and the significance of various gases and generation rates, a consensus is difficult to obtain. The principal obstacle in the development of fault interpretation as an exact science is the lack of positive correlation of the fault-identifying gases with faults found in actual transformers.
The result of various ASTM testing round robins indicates that the analytical procedures for gas analysis are difficult. have poor precision, and can be wildly inaccurate, especially between laboratories. A replicate analysis confirming a diagnosis should be made before taking any major action.
This guide is, in general, an advisory document. It provides guidance on specific methods and procedures to assist the transformer operator in deciding on the status and continued operation of a transformer that exhibits combustible gas formation, However, operators must he cautioned that, although the physical reasons for gas formation have a firm technical basis, interpretation of that data in terms of the specific cause or causes is not an exact science, hut is the result of empirical evidence from which rules for interpretation have been derived. Hence, exact causes or conditions within transformers may not be inferred from the various procedures. The continued application of the rules and limits in this guide, accompanied by actual confirmation of the causes of ga.s formation, will result in continued refinement and improvement in the correlation of the rules and limits for interpretation.
Individual experience with this guide will assist the operators in determining the best procedure. or combination of procedures, for each specific case. Some of the factors involved in the decision of the operator are: the type of oil preservation system, the type and frequency of the sampling program, and the analytical facilities available. However, whether used separately or as complements to one another, the procedures disclosed in this guide all provide the operator with positive and useful in formation concerning the serviceability of the equipment.
1.3 References
The following references should be used in conjunction with this guide:
[1] ASTM D2945-90. Test Methods for Gas Content of Insulating Oils)
[2] ASTM D3305-84 (Reaff. 89), Method for Sampling Gas from a Transformer.
[3] ASTM D36l 2-90, Test Methods for Analysis of Gases Dissolved in Electrical Insulating Oil by Gas Chromatography.
[4] ASTM D3613-87, Methods for Sampling Electrical Insulating Oils for Gas Analysis and Determination of Water Content.
IEEE C57.104 pdf download.