Abstract:

This paper takes the 25# insulating oil which is commonly used in current transformers as an example to test the ignition characteristics under the electric field generated by the electrode needles under different temperature conditions, and the ignition temperature characteristics of transformer oil under specified conditions are obtained, which can provide guidance for transformer fire mechanism and prevention research. The test results show that the critical temperature of ignition of the  25# insulating oil is about 172 ℃, under the condition of needle electrode electric field, with maximum electric field 6.56×10³ kV/m, and intensity spark energy 18 J. There are two ignition processes: deflagration and stable combustion. During deflagration, the maximum pressure in the combustion bottle is about 510 kPa, which is quite different from butane.

Key words: nsulating oil, electrode needle, electric field, ignition, temperature characteristics