Dissolved gas analysis (DGA) monitoring helps transformer owners track internal changes that may signal developing electrical or thermal problems. By testing transformer oil regularly and comparing results over time, maintenance teams can identify concerning trends, prioritize additional investigation, and make more informed decisions about their equipment.
At MVA Diagnostics, we combine in-house transformer oil testing with interpretation by chemists and transformer oil experts. Our DGA monitoring services help you understand what your results mean and determine the appropriate next steps for your assets.
What Is DGA Monitoring?
DGA monitoring is the ongoing evaluation of gases dissolved in transformer insulating oil. Heat, electrical activity, and the breakdown of insulating materials can generate gases that provide clues about conditions inside the transformer.
A single DGA test provides information about the equipment at the time of sampling. Monitoring builds on that information by comparing successive results. Changes in gas concentrations and the rate of gas generation help determine whether a condition is stable or developing.
Why Tracking DGA Trends Matters
A transformer’s testing history gives new results valuable context. A gas concentration that has remained relatively stable requires a different evaluation than one that has increased rapidly between samples.
DGA monitoring helps answer practical maintenance questions:
- Are gas concentrations remaining stable?
- Has a new gas pattern appeared?
- Are gases increasing more quickly than before?
- Does the equipment need more frequent sampling?
- Is additional testing or field investigation warranted?
Evaluating these trends alongside operating conditions and maintenance history helps turn laboratory results into useful information for asset management.
What Can DGA Monitoring Reveal?
Dissolved gas patterns can indicate thermal faults, electrical discharge activity, and changes involving the oil or solid insulation. Different conditions produce different combinations of gases, making interpretation an essential part of the monitoring process. Online DGA systems also track changing gas levels to help detect developing thermal and electrical faults.
DGA results should be evaluated in the context of the individual transformer. Equipment design, insulating fluid, loading, previous repairs, and oil processing can all affect the assessment. Identifying a concerning trend helps guide further investigation; it does not automatically establish the exact location or cause of a problem.
How Often Should Transformer Oil Be Tested for DGA?
The appropriate DGA monitoring schedule depends on the transformer’s condition, importance to operations, and previous results. A stable asset may follow an established routine sampling schedule, while equipment with abnormal or increasing gases may require closer monitoring.
An effective monitoring plan considers:
- Previous DGA results and gas trends
- Transformer age and operating history
- Loading and changes in operating conditions
- The consequences of an unexpected outage
- Recent maintenance, repairs, or oil treatment
- Recommendations from the diagnostic review
When results change, the sampling schedule should be reassessed. MVA helps customers determine appropriate follow-up testing based on their equipment and diagnostic findings.
Routine Sampling and Online DGA Monitoring
DGA monitoring can involve scheduled transformer oil testing, permanently installed online monitoring equipment, or a combination of both.
Routine laboratory sampling provides detailed results at selected intervals. Online monitors provide more frequent measurements between samples and can help identify changes as they occur. The gases measured and the capabilities of these systems vary by monitor.
MVA’s laboratory testing and diagnostic review support ongoing monitoring programs by helping customers evaluate oil sample results and plan follow-up actions.
Reliable Monitoring Starts With Accurate Sampling
Consistent sampling practices are essential for meaningful comparisons. Air exposure or contamination during collection can affect the sample and make DGA trends harder to interpret.
Each sample should be associated with the correct asset and sample location. Recording the sampling date, temperature, relevant operating conditions, and recent maintenance gives the diagnostic team additional context when reviewing changes.
MVA’s patented XQOhm® paperless transformer oil sampling platform makes it easier to capture sample information and connect it to the correct equipment. Customers can access results through email, the Dashboard, or the app, keeping diagnostic information accessible for ongoing maintenance planning.
DGA Monitoring With MVA
MVA performs all transformer oil testing in-house at our state-of-the-art laboratory. Our diagnostic team includes chemists and transformer oil experts who review results, assess developing trends, and provide recommendations to help customers manage transformer condition.
When findings warrant further investigation, MVA’s transformer field services provide additional support through electrical diagnostic testing, inspections, maintenance, and repairs. From the initial oil sample to follow-up field work, our team helps connect diagnostic findings with practical action.
Build a More Informed Transformer Maintenance Plan
Regular DGA monitoring creates a record of how your transformer is changing over time. That history helps your team recognize warning signs, focus maintenance resources, and plan the next steps with greater confidence.
Contact MVA Diagnostics to discuss your DGA monitoring needs or request a quote for transformer oil testing.