Transformers are vital components in electrical power systems. Their reliability and lifespan depend heavily on their internal conditions, particularly their insulation and cooling systems. One of the most effective methods for early detection of internal faults is through Dissolved Gas Analysis (DGA). This article will discuss the basics of DGA and why this method is important in transformer preventive maintenance.
What is Dissolved Gas Analysis (DGA)?
DGA is a laboratory testing method used to analyze gases dissolved in transformer insulating oil. These gases are formed as a result of thermal damage, overcurrents, or discharges (electrical surges) that occur within the transformer.
The resulting gases dissolve in the oil, and the type and concentration of these gases can provide early clues to the type of fault occurring within the system.
Main Gases Analyzed
Some of the main gases commonly analyzed in DGA include:
Gas Types Indicating Damage
Hydrogen (H2) All types of faults (general)
Methane (CH4) Mild overheating
Ethylene (C2H4) Moderate to severe overheating
Acetylene (C2H2) Discharge arcing (electrical arcing)
Ethene (C2H6) Oil overheating
Carbon monoxide (CO) Overheating of solid insulating materials (paper)
Carbon dioxide (CO2) Degradation of insulating paper
Testing Process
- Oil Sampling
Oil is taken from the transformer using a special syringe to maintain sample purity.
- Gas Extraction
Gases dissolved in the oil are extracted using a vacuum gas extraction device.
- Analysis with Gas Chromatography
Samples are analyzed in the laboratory using gas chromatography to measure the concentration of each gas type.
Interpreting DGA Results
There are several methods for interpreting DGA results, including:
- Gas Ratio (Key Gas Method)
Analyzes the ratio of specific gases to determine the type of fault (overheating, arcing, partial discharge).
- Duval Triangle Method
A visual technique based on a triangle graph that uses three key gases (C2H2, C2H4, CH4) to identify fault patterns.
- Total Dissolved Combustible Gas (TDCG)
Measuring the total amount of combustible gas to determine the severity of the condition.
Why is DGA Important?
- Early Failure Detection
DGA allows technicians to detect internal problems before major damage occurs.
- Avoiding Downtime
Condition-based maintenance is more efficient than waiting for a transformer to fail.
- Increasing Transformer Lifespan
With timely intervention, transformer life can be significantly extended.
Dissolved Gas Analysis (DGA) is an important diagnostic tool for monitoring the internal condition of a transformer. By understanding the gases formed due to thermal or electrical stress, technicians can identify potential faults early and take appropriate corrective action. In the world of electrical engineering, which demands high reliability, Dissolved Gas Analysis (DGA) is a key element in predictive maintenance strategies.
Hyprowira Laboratory currently provides Dissolved Gas Analysis (DGA) services. Please contact us for more information.
