Transformer insulating oil breakdown voltage test is one of the chemical analysis methods for transformer oil. It is measured by AC high voltage breakdown method, which is a necessary measurement item for transformers in new installation, overhaul or preventive test requirements.
The purpose of the oil breakdown voltage test on the transformer oil sample is to check the degree of contamination of the insulating oil by moisture or other suspended matter, and to determine whether it can be put into operation.
(1) The test process should be measured in an environment of 15~35℃ as far as possible, and the oil sample should be allowed to stand for 12 hours;
(2) It is recommended to use an automatic insulating oil breakdown voltage tester(oil BDV tester) to measure the test equipment;
(3) Before the test, the oil cup can be cleaned with gasoline, benzene or carbon tetrachloride and silk cloth, and dried in a drying furnace for use;
(4) Before the test, adjust the gap of the plane electrode to 2.5mm±0.1m, if the electrode has scratches, it is not available;
(5) Slowly run the insulating oil down the wall of the cup to reduce air bubbles, and the insulating oil can be 10mm higher than the electrode.
Take out the prepared oil cup, take out the measuring ruler from the electrode end of the oil cup, adjust the gap of the plane electrode and lock it, put the oil cup on the plane and pour 500mL of oil sample into the test tank, close the protective cover .
Turn on the power switch of the insulating oil withstand voltage tester, set the resting time and stirring time, or choose automatic measurement. After the setting is completed, the insulating oil breakdown voltage tester(oil BDV tester) will automatically test according to the set parameters, and the average value can be taken after the test is completed. .
It is recommended to use an insulating oil breakdown voltage tester to measure the insulating oil of the transformer. It is recommended to measure more than 3 times, and finally the average value of the three voltages can be used.
The average value of the breakdown voltage of the transformer insulating oil in the 10kv system before operation is ≥35kv; the average value of the transformer insulating oil in operation is ≥25kv, and the test below this voltage value is unqualified.