Electric equipment for large electrochemical installations

The increased demand for aluminum, magnesium, chlorine, copper, and zinc for war purposes has made the electrolytic processes for these materials the largest consumers of electric energy in this country. The most frequently encountered d-c and voltage requirements of these four principal electrolytic processes are discussed. An illustrative current-time and voltage-time characteristic curve for starting a chlorine cell line is shown, and the requirements that such characteristics impose on the electric equipment are discussed. The current-voltage characteristics of aluminum, magnesium, chlorine, and zinc cell lines are also shown. A typical installation of conversion equipment for an electrolytic process plant is given, and the reasons for selecting the particular types of electric equipment and its physical and electrical arrangement are discussed. As part of this discussion, there are included characteristic curves of rectifiers showing the effect of ignition control on power factor for 6-, 12-, and 36-phase combinations. A table giving a “rule-of-thumb” relationship between the number of phases and kilowatt limits which have been found in practice to provide operation reasonably free from telephone interference is included. There is also given a tabulation of phase shifter combinations, by means of which multiphase operation can be obtained with various combinations of standard six-phase rectifier transformers.