Progress in Transformer Dissolved-Gas Analysis
Join Dr. Jim Dukarm as he describes how physical chemistry and advanced statistics are breathing new life into transformer DGA. This article describes important advances like the use of fault energy indices and reliability statistics, and also provides an example that shows how these advances can improve fault detection and provide new risk assessment information.
Major Utility Implements Innovative Approach to Transformer Health Assessment
Find out how a major US utility is already using Reliability-based DGA to help identify and focus on at-risk transformers so they can implement an effective strategy to maintain and replace them as needed.
Delta-X Research Named 2019 Company of the Year for Asset Management Solution Providers
Delta-X Research has been named the number one Asset Management Solution Provider of 2019 by Utilities Tech Outlook Magazine. This Company of the Year award is part of the Magazine’s annual compilation of the Top 10 Asset Management Solution Providers.
Transformers Magazine July 2018: Interview With John Brett, Delta-X Research President & CEO
Get a great inside look at Delta-X Research, its history and what’s new, in this recent interview with our President & CEO, John Brett, in the July edition of Transformers Magazine.
Six Common Data Issues in Transformer DGA
Power transformers are designed to pass large amounts of energy through with very high efficiency, so in normal operation and in the absence of unusual stress there should be no degradation of the oil and paper insulation inside the transformer. Insulation damage or degradation resulting from an abnormal condition (“fault”) is almost always detectable by the formation of characteristic gaseous byproducts in the transformer oil. The main concern of transformer dissolved-gas analysis (DGA) is to detect, quantify, and interpret the active production of fault-related gas when it occurs. The first step in the interpretation of DGA data is to check for problems with the integrity of the data. Issues with the data must be recognized and dealt with before any conclusions can be reached ...
Identifying Transformer Faults with DGA
Imagine trying to explain power transformer fault detection to your child’s second grade class or to a CFO who does not have a technology background. The conversation might start like this: “like a doctor takes a blood sample from your body to detect an illness, an engineer may take an oil sample from a transformer to detect a problem or fault inside the transformer.” Okay, that was the easy part! Now how do you explain what to do with that oil sample and why it is important to the utility? DGA and Fault-Related Gases Dissolved gas analysis (DGA) is used to identify faulty transformers and to monitor transformers that are under stress or behaving abnormally. The key to trouble detection is understanding that abnormal heat and electrical discharges cause the production of fault-related gas ...
Transformer Reliability and Dissolved-Gas Analysis
Authors: J.J. Dukarm and M. Duval 2016 CIGRE Canada Conference October 17, 2016 Dissolved gas analysis (DGA) is widely used for transformer condition screening and assessment. Conventional DGA practice is to employ statistically derived limits for combustible gas concentrations and their increments or rates of increase for the purpose of classifying a transformer’s condition as acceptable, suspicious, or abnormal. The DGA condition assessment, in the form of numeric “condition codes,” is sometimes used as part of a transformer health index for prioritizing of testing and maintenance or for asset management functions such as replacement planning. The basis of this condition classification scheme is the seemingly reasonable assumption that higher fault gas levels must repre ...
TDCG, TCG, ETCG, ESHL, etc.
TOA4’s gas analysis report contains several alphabet-soup items which are explained here along with a couple of related items. In each case we start with the text label you see on the page or report, then the database field name, then the explanation. Most of this is general information about dissolved-gas analysis (DGA) in power transformers and other oil-filled apparatus, so even if you don’t use Transformer Oil Analyst (TOA) software, this may be of interest. But first a word about units. Dissolved-gas concentrations in insulating oil are usually expressed as parts per million by volume (ppm), which is the same as microliters of gas per liter of oil. Gas-in-gas concentrations are usually expressed as percent by volume. One percent by volume is ten thousand ppm. All of these volumes are ...
TOA4’s DGA Summary Report
One of the download links at the bottom of the equipment list page provides a DGA Summary report in .csv format. To use the summary report, first filter and sort the equipment list to show the equipment you want to include in the report. Then click the “Export DGA report data” link to download the report. Like all .csv files, it can be viewed and edited in a spreadsheet. For each equipment item contained in the equipment list as filtered and sorted, the report contains a row of data consisting of basic equipment information, the latest DGA sample date and re-sample date, gas concentrations, and the DGA condition code, diagnosis, and “chinese summary”. So far, we are aware of two different uses for this report, described below. Example 1: Problem report for maintenance personnel First, be s ...
TOA4’s Fluid Quality Index (fqindex)
The S. D. Myers Inc. laboratory reports the ratio of interfacial tension (IFT) and acid number as an indicator of the extent of oxidation of insulating oil. This ratio is the inspiration for TOA4’s Fluid Quality Index, which is calculated with an extra factor of 1000 to ensure that typical values of the index are not tiny decimal fractions. Here is the formula: fqindex = 1000*acidnum/ift Here, acidnum is the acid number (mg KOH/g), and ift is the interfacial tension (mN/m). The fqindex is calculated so that low values are good and high values are bad. Clean new oil has an fqindex below 1.0, and when fqindex reaches 10, the oil is in poor condition. While fqindex is good for trending the approximate oil quality and for detecting sudden changes which may need investigation, the acidity and I ...