Voltage unbalance in 3- and 4-wire delta secondary systems

An analytical method for finding voltage unbalance in 4-wire delta secondaries is introduced in which primary system voltage unbalance is represented, and the equation for total voltage unbalance at the load identifies the individual of unbalance. The effect of load representation, distribution transformer impedance, and primary system voltage unbalance is illustrated. It is shown that the open-wye-open-delta bank can magnify the voltage unbalance of a primary system, and that rolling phases might be a temporary solution to the voltage unbalance problem.>