Research of influence of electric insulation liquid on explosion and fire safety of high volt transformer
Explosion of the transformer can occur under the influence of both external (lightning) and internal (switching, arc) overvoltages. It is necessary to carry out checks of the condition of the insulating material during operation in order to timely detect developing failures and prevent accidental failures due to partial discharges on the equipment. In high-voltage electrical equipment, and in particular in transformers, the heat-removing and insulating medium is mainly mineral oil, due to its good dielectric and heat-conducting properties, but it is combustible, explosive and biodegradable. Currently, it is of interest to use plant materials for the production of insulating liquids. In our country, this is still experimental development, which, however, has practical applications abroad. Many researchers say that vegetable oil is better than mineral oil in terms of temperature characteristics and disposal. But it is worth noting that the conclusion about the increased fire and explosion safety of electrical equipment due to the transition to vegetable oils is made only on the basis that the flash point of mineral oils is two times lower. In this case, the factor of increasing the volume of oil and gas vapours in the transformer tank under the action of arc discharge arising from inter-turn faults was not taken into account at all. This article presents an attempt to numerically prove the effect of an insulating liquid on explosion and fire safety in the event of overvoltage using a boiling point in high-voltage equipment, and in particular in transformers. The research results reflect the effect on the possibility of explosion of the transformer and its ignition of vegetable oil. As a result of calculation there was obtained the excess pressure in the transformer for two types of oils. When solving the problem, the influence of the electric energy of the arc on the volume of gases formed in the oil was taken into account. As an example, for a specific type of transformer, overpressure is determined, leading to the destruction of the tank, which indicates the practical significance of the materials presented in the article.