In June 1975, the Engineering Recommendation Publication P16 of the Joint Council of Chief Engineers of the Electrical Council introduced for the first time in the UK a guide to the use of induction heating equipment and the effects of these equipment on the power supply system. A paper by Dixon and Harrison describes some typical induction heating equipment and the effects of these equipment on the power supply, and also quotes the information in the above-mentioned publication P16.
Here we reprint and briefly introduce these two materials to the readers so that users can understand some of the inherent problems in the application of high-power induction heaters.
induction furnace
In the above-mentioned engineering publication, a simple method has been mentioned that allows future users to estimate the effects of the equipment to be selected on the power supply. The correct approach is to consult with the local power management department at the beginning of the project to estimate these effects and ensure that effective measures are taken to minimize these effects.
When the induction furnace is closed and started, the current changes that occur may cause voltage drops and voltage increases in the impedance of the network system. In induction heating equipment connected phase to phase or phase to neutral, an imbalance in the phase voltage on the network may occur even under steady load conditions.
Induction heating equipment
Harmonic currents drawn by the equipment may cause harmonic voltage drops in the impedance of the network system and thus cause waveform distortion of the harmonic voltage. All these effects are proportional to the current drawn by the furnace into the network system and the impedance of the system. Therefore, in general, for a given size of furnace, the higher the level of short circuit tolerance of the power system, the lower this effect. Harmonic effects are further complicated by the fact that harmonic currents drawn from the furnace are not necessarily suppressed by the system impedance formed by the basic load current and by the fact that some branches of the power system may resonate.