
174 Aluminum Recycling
where
y is the optimal frequency
x is the capacity of the furnace in kg
For a furnace with a capacity of 3000 lb (1361 kg), the recommended frequency from
the expression would be 324 Hz, at the low end of what Figure 10.3 suggests. Afur-
nace with a capacity of 8000 lb (3629 kg) would have a recommended frequency of
111 Hz, well below that suggested by Hipple (1982).
Figure 10.4 shows a common power supply schematic for medium-frequency fur-
naces (Perkul, 2008). The equipment shown here is a parallel inverter, in which
the capacitor bank is connected in parallel with the induction coil; series inverters
are also used. The lack ...