Rapid dissolved gas analysis by means of electrochemical gas sensors

Abstract

Rapid, introductory analysis of gases dissolved in insulating oil PGA) carried out in the field can help in effective screening of faulty transformers as well as minimising number of classical laboratory chromatographic DGA tests. It is also crucial for shortening a time gap between oil sampling and its analysis. A novel approach to DGA is presented in this paper. A rapid analysis of oil samples is carried out by means of a portable analyser fitted with electrochemical gas sensors. Extraction of gases from the oil matrix is achieved by means of a dynamic, closedloop stripping process. The analyser, which was built, is controlled by a microprocessor and may be operated in the field as an autonomous device. The system incorporates only two gas sensors and due to an extended set of their output signal wave descriptors used for the analysis it allows for a reliable identification of fault gases present in an oil sample. The identification of basic transformer fault types is illustrated on the basis of analytical results obtained for artificial oil samples prepared in a laboratory as well as those taken from transformers in-operation.

Usage of nanotechnology based gas sensor for health assessment and maintenance of transformers by DGA method

“…These changes depend on the gas sensing material and usually involve changes in its electrical properties. In the past Zylka and Mazurek [10] has developed a portable analyzer, fitted with more than one electrochemical gas sensors, for online monitoring of the transformer. In his prototype he used four sensors to detect four types of gases dissolved in the oil.…”

Mathematical model for predicting the state of health of transformers and service methodology for enhancing their life

“…Results are used to predict its in-service behavior, which is essential to avoid catastrophic failures and costly outages of the power system. Presently DGA has gained worldwide acceptance as a diagnostic method [1,25,28] for the detection of internal faults of the transformers and for monitoring their health. Behavior of transformers is so complex that it is difficult to detect the sources or the causes of gas generation.…”

Aging Study and Lifetime Estimation of Transformer Mineral Oil

“…Hydrogen is generated from degradation of the oil at temperatures above 120°C and study generates hydrogen at temperatures over 140°C. Carbon monoxide and dioxide are generated significantly in the aged oil at temperatures greater than 110°C [5][6][7] .…”

“…The principal mechanism of oil aging is oxidation, which results in acids and other polar compounds being formed. These oxidation products will have a deleterious effect on the study degradation processes [5] . The main oil properties are divided to the physical, chemical and electrical characteristics.…”