Collecting Oil Sample from Oil Immersed Electrical Equipment

Process of Collecting Oil from Oil Immersed Electrical Equipment Like Transformer.
We collect oil sample for performing different tests on the oil to determine different physical, chemical and electrical characteristics of the oil. The sample is the representative of the oil inside the equipment. That is why, we take special care during collecting oil sample from the equipment. Otherwise surrounding atmosphere may affect the characteristics of the oil which may differ the outcome of the tests form the actual results.

The normal procedures of collecting oil from a transformer or other oil immersed electrical equipment are given in following points

1. We should always take at least 1 to 2 liter of oil from bottom valve or oil sample valve (if available) depending upon the tests to be performed on that sample.
2. We should ensure that sampling is done by well experienced technical personnel.
3. We should not take sample of the oil in rainy, stormy, foggy, and snowy weather since it can affect the water contaminant of the oil. We should also avoid oil sampling in high atmospheric humidity for same reason.
4. We should use dry and clean containers preferably made of amber colored glass or clear glass or seamless stainless steel bottle. We can also use plastic bottle provided its suitability has been approved.
5. First we should run of some of the oil from oil sampling valve of the equipment to ensure the removal of any contaminants in the orifice of the valve.
6. Before toping up the bottle, we should rinse the sampling bottle with some oil
7. We should fill the bottle slowly and gently. We should allow the oil to flow against the wall of the bottle to avoid any formation of air bubble in oil so that no air can be trapped in the sample.
8. We should fill the bottle up to 95% of its capacity
9. Now we carefully close the bottle.
10. We must avoid any adisive tape like thing at the cover.
11. Now, the bottle must be labeled with
    • Name of the equipment from where sample is collected
    • Rating of the equipment
    • Serial No of the equipment
    • Installed location of the equipment
    • Other identifications of the equipment if required.
    • Temperature of the oil at the time of collection
    • Date of collection
    • Identification of the sampling point (whether it is from top or bottom)
12. If we collect the sample oil in clear glass bottle, we should keep in in dark place.