Busbar Current Measurement in Induction Heating Furnaces Using a Pick-Up Coil

Induction heating installations often use busbar systems to connect the inductor coil, which encloses the workpiece, with the remotely positioned generator. The busbar carries a high current, at a high frequency and a high temperature, which makes current measurement complicated. In this paper, several measurement methods are compared, and their usefulness for this particular application is discussed. A simple pick-up coil is proposed as a reliable, non-intrusive current measurement technique, which is easily adaptable to different busbar shapes and current levels. The effects of variations in frequency and pick-up coil position are explored with finite element simulations. Measurement results are presented and compared with simulation results. Some practical pick-up coil implementations and calibration methods are proposed.