Investigation of a Damaged Filter-Compensation Unit

Nowadays, almost 50% of steel is made from steel scrap by electric heating and melting, mostly in arc furnaces. The electric arc furnace with all its equipment is often a key unit in the entire steel manufacturing process. Therefore, all electric arc furnace equipment must be designed with respect to the requirement of high reliability for long-term operation under very hard conditions in the steel mill. A very important part of the furnace installation is the device that compensates the undesirable reactive power and also reduces the voltage distortion in the supply grid. A filter-compensation unit is used for this purpose. During the operation of the filter-compensation unit in an investigated furnace installation a failure occurred, whose causes are described in this paper.