In three-phase transformers, especially those that are wye-connected, what do you expect to see in terms of phase currents?

In a wye-connected three-phase transformer, the expectation is that the phase currents will be equal under balanced load conditions. A balanced three-phase system represents a scenario in which the loads on all three phases are identical. In such cases, the currents flowing through each phase would be equal, leading to three equal currents.

Option C, suggesting two high currents and one lower current, implies an imbalance in the phase currents. This condition might occur in situations with unequal loading, fault conditions, or improper connections, but for typical operations and maintenance training regarding wye-connected transformers, it is essential to focus on the standard operation under balanced conditions.

Thus, while an imbalanced scenario can happen in practice, the fundamental principle regarding phase currents in a functioning three-phase wye-connected transformer is that they are designed to carry three equal currents. Properly addressing and understanding these aspects is crucial for the maintenance and operation of substations to ensure stability and efficiency in power distribution.