Relation between voltage drop and load balance in an open-Y distribution circuit

WHEN supplying large lighting loads such as theaters, hotels, or department stores by the 4-kv primary circuits, in many cases it has been desirable to utilize only 2 phases of the 3-phase 4-wire system. These loads are fed by 2 transformers connected in open Y on both the primary and secondary. Such an arrangement is made in order to avoid connecting large lighting loads on only one phase of the 4-kv circuit, thus maintaining a better load balance on the primaries and also obtaining an economical 3-wire secondary distribution system.