Analysis the electrical parameters of a high-frequency coreless induction furnace

The paper analyzes the most important electrical parameters of a coreless induction furnace, having a capacity of 7 kg molten iron (i.e. 2.5 kg aluminum). The furnace is supplied by a high-frequency (HF) static converter ITS2 12K20, with the output frequency 5... 12 kHz, 600...1200 Vac rated HF voltage, and 20 kW rated HF power. Monitoring of electrical parameters was done for an aluminum charge, using a power quality analyser CA8334. The measurement results showed that induction furnace operation causes unbalance and harmonics in three-phase currents absorbed from the distribution network. Harmonics in the line currents are caused mainly by static converter, and to a lesser extent by furnace load and interaction of eddy currents induced in the charge and the magnetic field of the inductor. To reduce the negative impact of the current harmonics on the distribution network is necessary the design and achievement of electrical filters for odd-order harmonics (5th, 7th, 11th, 13th, 17th, 19th, 23th, 25th).