Table of Contents
What is DGA in transformer oil?
Dissolved gas analysis (DGA) is an examination of electrical transformer oil contaminants. Insulating materials within electrical equipment liberate gases as they slowly break down over time.
Which test detect the presence of water in transformer oil?
The crackle test is a standard laboratory test to detect the presence of water in lubricating oil. A drop of oil is placed on a hotplate that has been heated to approximately 400° F. The sample then bubbles, spits, crackles or pops when moisture is present.
What is BDV test in transformer?
BDV test means the Breakdown Voltage Test. This test is performed for verifying the dielectric strength of the oil of the transformer. Dielectric Strength is the maximum capacity to resist the voltage of insulating oil. This test demonstrates the dielectric Strength of Transformer Oil.
What is PPM test in transformer?
PPM stands for Parts Per Million. It is used to measure the weight of moisture divided by the value of oil. The moisture content in oil lowers the insulating system dielectric strength that permits flashover to harm a transformer. For example, for mineral oil, a generally accepted maximum moisture content is 35 ppm.
Is there water in a transformer?
Water in transformers can be found in different parts of the insulation system. It can accumulate in solid insulation, be dissolved in oil, or be found in the form of liquid water at the core or bottom of a transformer.
Why DGA test is required?
It is also referred to as a DGA test. Whenever a transformer undergoes abnormal thermal and electrical stresses, certain gases are produced due to the decomposition of the transformer oil. That is why it becomes necessary to analyze the number of different gasses dissolved in transformer oil in service.
What is water content in oil?
Most industrial oils such as hydraulic fluids, turbine oils, etc., can hold as much as 200 to 600 ppm of water (0.02 to 0.06 percent) in the dissolved state depending on the temperature and age of the oil, with aged oils capable of holding three to four times more water in the dissolved state than new oil.
How can we remove oil from water?
One of the easiest ways to remove hydrocarbons from water or coolant is by using a belt oil skimmer. It is a low maintenance, easy to use tool for removing oil from water or coolant. Belt oil skimmers, such as the Model 8, work because of the differences in specific gravity between oil and water.
What are the different types of transformer oil testing?
Different Kinds of Transformer Oil Testing 1 Visual Examination. 2 Color Analysis. 3 Dielectric Breakdown Voltage (BDV Test) With this test the dielectric strength of the insulating oil is tested or on other words we measure the voltage at which the oil fails
What is the acid content of transformer oil?
New transformer oil generally have no acid content by may develop because of oxidation and contamination. The test is carried out by measuring the amount of potassium hydroxide (KOH in mg) required to neutralize the acid in one gram of oil. This test is conducted using the international standard ASTM D974. Polychlorinated Biphenyls (PCB) Content
What is the minimum dielectric strength of transformer oil?
This test is conducted using the international standard ASTM D877 which also specifies that the new transformer oil should have a minimum dielectric strength of 35kV. The BDV is measure in kV.
What do different gases dissolved in the oil of a transformer indicate?
Different gases dissolved in the oil indicates different kinds of thermal and electrical stress occurring inside the transformer. The internal standard ASTM D3612 is used to carry out this test.