In the cast house of Hoogovens Aluminium NV in Duffel, Belgium, nearly all melting furnaces are channel induction furnaces. A smooth operation of these furnaces is important. The inductors that are the heating elements of these furnaces are susceptible to wear and clogging. As inductors have to be reliable and predictable, they are monitored systematically. An inductor is an a.c. device for heating liquid metals. Electrically, it is similar to a short-circuited transformer. Its resistance and reactance depend on the resistances and reactances of its primary and secondary circuits. The secondary circuit's resistance and reactance are dependent on the shape and the size of the inductor channels. The changes of these channels due to wear or clogging can be assessed measuring the resistance and reactance of an operating inductor. A comparison with the regular mechanical measurements has shown that the electrical method determines an inductor's state with sufficient accuracy to monitor geometry changes. Therefore it has been adopted in daily operations.
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