The electrical operating characteristics for the furnace at five different transformer tap positions are presented in Table 1, which also gives the data taken during a 3-phase short-circuit test (from the so-called dip test) performed at tap no. 8.
These electrical measurements were taken by two methods. One method employed watt hour, VAr hour and V2 hour measurements against time in several increments by pulsing instruments connected at the furnace transformer primary metering point for the commonly used tap positions 33 through 10. The other measurements, taken concurrently with these measurements, were monitored by means of averaging meters (I2dt) in the primary-current transformer circuit.
From the acquired data of the dip test, the furnace impedance, both resistive and reactive components, on a per phase basis, can be calculated, using either of the methods outlined elsewhere.
From the measurement data, the arc characteristics will now be determined, such as arc power, arc length, arc resistance and arc voltage. This will be done in the following example for tap position 33, using the method described. Results for the remaining tap positions are listed in Table 2.
Calculation of arc-circuit asymmetry in electric-arc furnaces
Peter F. Ryff