Abstract: Improved and simplified measurement of the level of molten metal in a crucible heated by an induction coil utilizes a variable frequency power supply for the induction coil. Power supply frequency is changed to maintain the power provided to the coil substantially constant, independent of variations of power factor in the coil circuit. Detection of the frequency of power supplied to the induction coil provides an indication of the changes in power factor of the coil due to changes in the level of molten metal surrounded by the coil, and thus of the level of the molten metal.
Type:
Grant
Filed:
October 13, 1981
Date of Patent:
May 1, 1984
Assignee:
Electric Power Rsearch Institute, Inc.
Inventors:
Paul G. Friedmann, Frank N. Patris, Allan W. Tomalesky