CONTROL DEVICE FOR MOLTEN STEEL HEATING APPARATUS IN TUNDISH

摘要

PURPOSE:To surely prevent the pinch effect by using each change of current for each phase as premonitory phenomenon of development for the pinch effect and controlling power supply to a heating apparatus, to detect in advance the development of the pinch effect. CONSTITUTION:The power from three-phase AC source is supplied to a single-phase heating coil 3 of a channel type induction heating apparatus through a three-phase transformer 1 and a tap changer 2. Then, the single-phase induction coil 3 for heating and a condenser 4 for improving the power factor are connected in parallel to U-phase and W-phase, and a phase balanced reactor 5 and a phase balanced capacitor 6 for supplying the power to the induction coil 3 for heating are connected to V-phase. By this constitution, the current for each phase is detected by a current transformer 7, at the time of showing, that IW for W-phase current has tendency to decrease, IU for U-phase current has tendency to increase and IV for V-phase current is almost unchanged, a pinch detecting device 8 judges as the premonitory phenomenon of development for the pinch effect, and then a pinch predicting signal and a pinch developing signal is inputted to a control device 9 and by driving the tap changer 2, an input voltage supplied to the induction coil 3 for heating is reduced, to prevent the development for the pinch effect.