Product Description

Dissolved gas analysis is a certain method to diagnose incipient fault of transformers through the correlation between the content of gases dissolved in transformer oil and a particular malfunction. An on-line monitoring system is used to detect the concentrations of gases (H2, O2, CO, CO2, CH4, C2H2, C2H4, C2H6) dissolved in transformer oil.

In order to maximize the lifetime and efficacy of a transformer, it is important to be aware of possible faults that may occur and to know how to catch them early. Regular monitoring and maintenance can make it possible to detect new flaws before much damage has been done.

The four main types of transformer faults are: 
1. Arcing, or high current break down.
2. Low energy sparking or partial discharges.
3. Localized overheating, or hot spots.
4. General overheating due to inadequate cooling or sustained overloading.

These faults can all lead to the thermal degradation of the oil and paper insulation within the transformer. One way to detect them is by evaluating the quantities of hydrocarbon gases, hydrogen and oxides of carbon present in the transformer. Different gases can serve as markers for different types of faults. For instance,

* Large quantities of hydrogen and acetylene (C2H2) can indicate heavy current arcing. Oxides of carbon may also be found if the arcing involves paper insulation.
* The presence of hydrogen and lower order hydrocarbons can be a sign of partial discharge
* Significant amounts of methane and ethane may mean localized heating or hot spots.
* CO and CO2 may evolve if the paper insulation overheats; which can be a result of prolonged overloading or impaired heat transfer.

Dissolved gas analysis, is a test used as a diagnostic and maintenance tool for machinery. Under normal conditions, the dielectric fluid present in a transformer will not decompose at a rapid rate. However, thermal and electrical faults can accelerate the decomposition of dielectric fluid and solid insulation. Gases produced by this process are all of low molecular weight, and include hydrogen, methane, ethane, acetylene, carbon monoxide and carbon dioxide. These gases will dissolve in the dielectric fluid. Analyzing the specific proportions of each gas will help in identifying faults. Faults detected in such a way may include processes such as corona, sparking, overheating and arcing.
Abnormal functioning within a transformer can be caught early by studying the gases that accumulate within it. If the right countermeasures are taken early on, damage to equipment can be minimized.

Several methods of interpretation of DGA in transformers in service are provided in IEC Standard *****1, the IEEE Guide C*7.***2, as well as in published reviews on the subject. The offered system is capable of providing the same, i.e.

• Doernenburg Ratio
• Roger’s Ratio
• Duvals Traingle
• IEC Ratio