Immersed-oil power transformers in the power system play an important role as voltage conversion. The transformer’s insulating oil can cool the transformer down and strengthen the ability of power supply. A transformer fault will cause electricity interruption and may result in a serious problem. Therefore, detection of transformer’s fault is very important task. The insulating oil gas analysis (DGA) is a good way to diagnose the transformer fault and has been widely used by many power companies in the world. This is because that the insulating oil analysis can predict incipient faults via the analysis of the gases generated from the insulating oil. If the transformer’s fault can be diagnosed accurately, and then the transformer will be well maintained, the electricity interruption caused by transformer’s fault can be avoided.

The insulating oil measurement is via chromatography instrument (ASTM D3612). The measured data of nine kinds of gas, namely Ethane (C₂H₆), Hydrogen (H₂), Methane (CH₄), Carbon Dioxide (CO₂), Ethylene (C₂H₄), Acetylene (C₂H₂), Carbon Monoxide (CO), Nitrogen (N₂), and Oxygen (O₂) can be obtained [1] . Any measured data of nine kinds of gas being larger the standard criterion of ASNI/IEEE C57.104 indicated that we have to check what happens in the transformer. In this paper, we investigate the DGA methods and employ the ANSI/IEEE C57.104 Standard Rule and IEC Basic Gas Ratio method to develop a heuristic diagnosis tool which is carried out by a MATLAB program. The user only keys in the measured data of H₂, CH₄, C₂H₆, C₂H₄, and C₂H₂ and the developed diagnosis tool can provide a diagnosis result by texts and figures.

Total Combustible Gases are made up of H₂, CH₂, C₂H₆, C₂H₄, C₂H₂ and CO, and its definition as follows, is shown in formula (1) (unit ppm):

The immersed oil transformer’s insulating oil along with the transformer operating time and the measured of the cyclical time has made vital relations with its life-span, however its increase value on IEEE C57.104 standard, as shown in formula (2):

where, R is increase of the TCG value (a milliliter/day), S_T is testing value, S_O is previous value, V is measured from the transformer’s volume as well as T is measured from the duration of days. So the quantity of the TCG, rely on the R’s value which is classified “Normal”, “Attention”, “Abnormal”, and “Danger” etc., four kinds of symptom shown in Table 1.

Be based on Dissolved Gas Analysis (DGA), the value of insulating oil has been diagnosed either normality or abnormality in the body of transformer. In recent years, a lot of techniques have been developed to predict diagnosis for the transformer latent failure points by the gas content, such as the Key Gas method, Duval triangle method as well as Dornenberg method, Roger method, Liner SVM diagnosis etc., this paper took the Diagnosis of IEC Basic Gas Ratio method and ANSI/IEEE Standard Rule to design a Transformer Fault Diagnosis Tool by the MATLAB program which described next sections below.

The diagnosis tool of insulating oil can be diagnosed by well usage of different method and specification after incorporating some kinds of human experience. The flow chart of the proposed diagnostic method is shown in Figure 1. With well-designed man-machine interface, the developed program can be implemented by computer to avoid man error and achieve more reliable diagnosis result.

For more simple, precise, and effective to diagnose, I read lots of diagnosis’s approach of transformer’s insulating oil which were such good paper as “Support Vector Machine-Based Fault Diagnosis of Power Transformer” [4] and “Duval Triangle: A Noble Technique for DGA in Power Transformer” [5] , and etc. Eventually, from those methods and approaches were appraised carefully, this paper takes ANSI/IEEE C57.104 Standard Rule and IEC Basic Ratio methods to design the program. The goal is it cans double check to complete accurate diagnosis.

The accuracy of interpretable plots by concept of digital rule establishes during implementation after input the concentration of H₂, CH₄, C₂H₆, C₂H₄, and C₂H₂. This paper designs a set of highly fast way to diagnose of transformer incipient fault by IEC Basic Gas Ratio and the Standard of ANSI/IEEE C57.104 diagnosis method. From the report’s from the obtained texts of the ANSI/IEEE C57.104 standard diagnosis and the figure of IEC Basic Gas Ratio to judge what was in body of transformer.

As we know that, how to detect the transformer fault quickly and accurately is not an easy job. In this paper, we have investigated the DGA methods and developed a quick method to diagnose the malfunction of power transformers by using ANSI/IEEE C57.104 diagnosis specification and IEC Basic Gas Ratio method. We have developed the transformer fault diagnosis tool by a MATLAB program. The real measured data of the transformer oil taken from Ba Dou D/S # 4DTr transformer of Taiwan Power Company are used to verify the validation and accuracy of the developed diagnosis tool. This tool will be useful for engineers and technicians who are in charge of transformer’s maintenance.

Symbols: N (Normal), Ac (Arc), Pd (Partial Discharge). 1 (Program out for 1), 0 (Program out for 0), C1 (Case1), C2 (Case2), C3 (Case3), C4 (Case4), C5 (Case5), C6 (Case6), C7 (Case7).

The author would like to thank that the relevant information of this paper was provided by the department of the supply, Tai Pei branch supply, and Research Institute of Taiwan Power Company.