Which of the following would not be a characteristic of an ideal three-phase power system?

An ideal three-phase power system is characterized by symmetry and balance, which results in a more efficient and stable operation. In such a system, all phase currents are equal, phase angles are perfectly balanced, and the neutral current is minimal or ideally zero if all phases are perfectly balanced.

The option regarding phase currents being varying does not fit the characteristics of an ideal three-phase system. In an ideal setup, phase currents should remain constant and equal, reflecting a balance in the system. Variations in phase currents could indicate issues such as unbalance or load changes, detracting from the ideal conditions expected in a three-phase system. Thus, this characteristic of varying currents denotes a departure from the ideal scenario, making it the correct choice for what would not be a characteristic of an ideal three-phase power system.