except in the case of medium-frequency systems, are designed as step transform- ers. As a rule, 10- or 12-step secondary windings are used for mains frequency systems. The switching takes place in the no-load condition on the secondary side. The top 5 or 6 steps are designed for nominal output, while at the lower steps, the output falls by the square of the reducing voltage. The lowest step is set so that the relevant furnace can still be kept hot at 60% of its capacity, with- out the temperature rising significantly. In the case of a 12.5-t furnace, the output used by the furnace should be about 140 kW. If the maximum voltage is 2,000 V for 2,600 kW, the lowest voltage step must operate at 465 Volt.
Alles über Gießereien mit Lexikon