Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Frequency of cyclic current or voltage
Patent
1985-04-12
1986-09-16
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Frequency of cyclic current or voltage
324 55, 324158R, 364571, 340655, G01R 3108, G06F 1520
Patent
active
046124985
ABSTRACT:
The specification discloses a computerized monitor for a coreless induction furnace. The monitor includes a first potential transformer connected across the coil and a second potential transformer connected between one end of the coil and an electric ground. The relative location of a ground fault along the length of the coil is approximated by computing the ratio of the transformer outputs. An impedance variation look-up table is included to provide correction factors for the approximated location to compensate for variations in impedance along the length of the coil. The monitor further includes a first current transformer in the coil power line and a second current transformer in the melt bath ground. Internal ground faults are detected by computing the phase difference between the coil and ground currents. A graphic representation of the furnace is also generated to illustrate the location of the ground fault with respect to turns and yokes of the coil. The monitor also calculates liner wear by determining melt bath volume, which is inversely proportional to melt bath resistance, which in turn is proportional to coil resistance. If the furnace being monitored is provided with more than one coil, a differential current transformer is connected across each coil to detect the fault grounded coil when the transformer associated with the faulted coil exhibits a substantially nonzero output.
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Eisenzopf Reinhard J.
Solis Jose M.
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