IEEE Std C57.104-1991 IEEE Guide for the Interpretation of Gases Generated in Oil-Immersed Transformers -Description
Abstract: Detailed procedures for analyzing gas from gas spaces or gas-collecting devices as well as gas dissolved in oil are described. The procedures cover: (1) the calibration and use of field instruments for detecting and estimating the amount of combustible gases present in gas blankets above oil, or in gas detector relays; (2) the use of fixed instruments for detecting and determining the quantity of combustible gases present in gas-blanketed equipment; (3) obtaining samples of gas and oil from the transformer for laboratory analysis; (4) laboratory methods for analyzing the gas blanket and the gases extracted from the oil; and (5) interpreting the results in terms of transformer serviceability. The intent is to provide the operator with positive and useful information concerning the serviceability of the equipment. An extensive bibliography on gas evolution, detection, and interpretation is included.
Keywords: gas analysis, oil, oil-filled transformers, transformers
Content
1. Introduction
1.1 Scope
1.2 Limitations
1.3 References
1.4 Definitions
2. General Theory
2.1 Cellulosic Decomposition
2.2 Oil Decomposition
2.3 Application to Equipment
2.4 Establishing Baseline Data
2.5 Recognition of a Gassing Problem—Establishing Operating Priorities
3. Interpretation of Gas Analysis
3.1 Thermal Faults
3.2 Electrical Faults—Low Intensity Discharges
3.3 Electrical Faults—High Intensity Arcing
4. Suggested Operating Procedures Utilizing the Detection and Analysis of Combustible Gases
4.1 Determining Combustible Gas Generating Rates
4.2 Determining the Gas Space and Dissolved Gas-in-Oil Equivalents
4.3 Monitoring Insulation Deterioration Using Dissolved Gas Volume
4.4 Evaluation of Transformer Condition Using Individual and TDCG Concentrations
4.4.1 Determining the Transformer Condition and Operating Procedure Utilizing TCG in the Gas Space
4.4.2 Determining the Operating Procedure and Sampling Interval From the TDCG Levels and Generating Rates in the Oil
4.5 Evaluation of Possible Fault Type by the Key Gas Method
4.6 Evaluation of Possible Fault Type by Analysis of the Separate Combustible Gases Generated
4.6.1 Evaluation of Possible Fault Type by the Doernenburg Ratio Method
4.6.2 Evaluation of Possible Fault Type by the Rogers Ratio Method
5. Instruments for Detecting and Determining the Amount of Combustible Gases Present
5.1 Portable Instruments
5.2 Fixed Instruments
5.2.1 Method 1
5.2.2 Method 2
5.2.3 Method 3
6. Procedures for Obtaining Samples of Gas and Oil From the Transformer for Laboratory Analysis
6.1 Gas Samples for Laboratory Analysis
6.2 Gas Dissolved in Oil
7. Laboratory Methods for Analyzing the Gas Blanket and the Gases Extracted From the Oil
7.1 Determination of Total Dissolved Gas
7.2 Determination of Individual Dissolved Gases
7.3 Determination of Individual Gases Present in the Gas Blanket
