Short-circuit between two parallel turns in an induction furnace which can occur due to improper insulation.
Voltage must be switched to a low level in order to avoid leakage current at intermediate plants in case of excessive moisture e.g. due to insufficient drying. These leakage currents are usually very low so that short-circuits do not occur immediately. However, this generates an endangered spot in the long term which can be further damaged with each new charge.
A short-circuit (between the turns) can occur in the course of a “coil lifetime” e.g. after 18 months of operation if a new charge is started with excessive voltage under humid weather conditions and with condensate formation at the coil copper. The copper of the coil is removed during electrode welding resulting in water leakage. If the leaking water cannot escape through the coil gaps, it will finally reach the melt inevitably causing the explosion of water vapor. In order to avoid these explosions, most of the furnace manufacturers use an open coil construction with construction elements which are permeable to water.