The supply of single-phase power from three-phase systems

The various methods of supplying single-phase power are considered under the five heads enumerated in the next column. Of these, No. (4) and No. (5) are dealt with in some detail. Under No. (4), phase balancers are divided into stationary and running balancers. A qualification is added to Steinmetz´s statement on stationary balancers. If is shown that the elimination of the alternating component of the power does not necessarily bring about a ¿ balance of the phases,¿ defined on page 111. The correct method of balancing the phases in the case of an electric furnace working 0¿7 power factor is developed for both chokecoil balancer and condenser balancer. Running balancers are classified under five sub-headings (a) (e), page 112, according to the method used of overcoming the impedance drop in the windings. The graphic diagrams of the different types are given, and the merits and drawbacks of these balancers discussed. Under head No. (5) a new type of balancing transformer is described. A calculation of a balancing transformer for feeding a 400-kW electric furnace is worked out. The figures obtained on the tests of the machine at no load and at full load are given.