BALANCED WYE-WYE CONNECTION

BALANCED WYE-WYE CONNECTION

The balanced three-phase wye-wye connection is shown below. Note

that the line impedance for each of the individual phases in included in the circuit. The line impedances are assumed to be equal for all three phases. The line currents (IaA, IbB and IcC) are designated according to the source/load node naming convention. The source current, line current, and load current are all one in the same current for a given phase in a wye-wye connection. 

Assuming a positive phase sequence, the application of Kirchoff’s voltage law around each phase gives:

where Ztotal is the total impedance in each phase and 2Z is the phase angle associated with the total phase impedance. The preceding equations can be solved for the line currents.

Example

Problem:

For the Y-Y circuit, find the line currents, the line voltages, and the load voltages.

Solution:

remember: A balanced Y-Y system is a three-phase system with a balanced Y-connected source and a balanced Y-connected load.