The Greaves-Etchells furnace

The Greaves-Etchells system suses the delta-Y connection, which is admittedly the best combination for producing evenly loaded phases. The transformers are connected delta on the primary side and Y on the secondary. One of the legs of the transformer is applied directly to the bottom of the furnace by means of copper busbars and a copper plate, which conducts the current through a bottom composed principally of magnesite and dolomite, in such a way that there is a graded resistance, beginning with a low resistance and ending high. The other two legs of the transformer are connected to movable electrodes, which extend down through the roof. Regulation is then maintained by the usual types of furnace regulators. It is readily seen that by this arrangement there is no possibility of either movable electrode ever touching the bath or extending into it, without causing a short circuit. This feature alone is very valuable, and one which is very hard to handle in a large number of other types of furnaces.