| 摘要 |
<p>For the purpose of giving warning of, and/or preventing, the overheating of the melt in an induction crucible furnace which is supplied with current of constant frequency, the power factor or the impedance of the furnace is monitored by a measuring means during the melting of a charge in the furnace. The measuring means is connected to a signal transducer which is arranged to emit a signal when, during the melting process, the power factor or the impedance has remained stationary at a certain value and remained unchanged at that value for a certain, suitably adjustable, time and/or has decreased to a certain adjustable value. The signal transducer may include a supplementary device for reducing the power of the furnace when one of said signals has been emitted.</p> |
