Improving accuracy and confidence in your DGA results
Dissolved gas analysis (DGA) is the only way to detect a range of internal faults in transformers.
Although it isn’t an exact science, evaluation and interpretation based on statistics has been used for transformer condition assessment for decades. Online DGA monitoring has been available since the late 1990s and there are now various online gas monitors on the market each with their own technical specification, making it challenging for transformer owners to compare and evaluate the different options.
To make the field even more complicated for utilities, laboratory DGA plays a role too. Vaisala’s white paper, The world of DGA and its uncertainties describes various factors to consider when examining a monitor’s technical specifications and evaluating its performance, especially against laboratory DGA results.
The main challenge is that there isn’t any explicit international reference available for DGA; instead, all methods include calculation and oil-specific parameters. Even various mineral oils are not equal from a DGA perspective. Online monitors have proven their value over oil samples in gas trending and detecting quickly evolving and changing faults.
However, adequate accuracy is also needed, because inaccurate DGA results may lead to erroneous fault diagnoses, especially if gas ratios are close to a fault zone boundary.
In addition, inaccurate results may lead to the wrong action being taken on a transformer if concentration values are close to alarm values used at a utility.
Download Vaisala’s white paper today for insights into:
- Challenges in measurement accuracy
- Consequences of inaccurate measurement
- Laboratory DGA and related uncertainties
- Advances in online DGA monitoring
- How to compare the performance of online DGA monitors and Laboratory DGA