When the insulating oil dielectric loss tester measures the loss value of insulating oil, cleaning the oil cup is a very important preparation. Some unreliable measurement results are often caused by incomplete cleaning of the oil cup. Therefore, strict cleaning methods must be followed to obtain repeatable and reliable measurement results.
When doing the identification test of the loss factor of insulating oil, the oil cup should be thoroughly cleaned before each test. The cleaning steps are as follows:
a. Completely disassemble the oil cup, and wash all parts with chemically pure petroleum ether (distillation range 60-90℃) and benzene in turn.
b. Rinse all parts with acetone, then wash with neutral detergent.
c. Boil all parts in 5% trisodium phosphate in distilled water for 5 minutes and rinse several times with distilled water.
d. Boil all parts in distilled water for at least 1 hour.
e. Put all the parts into the oven controlled at 105-110℃ for drying, and the drying time is not less than 1 hour.
f. Assemble the oil cup when all parts are cold enough not to be hot to the touch.
Note: In the general routine test of the loss factor of insulating oil, the cleaning method of the oil cup can be simplified, that is, the items c and d of the above cleaning method are omitted, and all parts are rinsed with distilled water several times instead. After that, go directly to item e.
In addition, when performing routine tests on a batch of oil samples continuously, if the loss factor of the previous oil sample is less than the specified value, it is not necessary to clean the oil cup when the next oil sample is made, but the second oil sample must be used. Rinse the oil cup more than three times.