Final answer:
Changing a distribution system from Delta to Wye increases the load carrying capacity by nearly 200% (173%) due to the relationship between line voltage and phase voltage in Wye systems.
Step-by-step explanation:
By changing a distribution system from Delta to Wye, you will increase the load carrying capacity by 173%, which is almost equivalent to 200%. This is because in a Wye system, the line voltage is √3 (approximately 1.732) times higher than the phase voltage, which means each transformer can carry √3 times more load for the same current. Therefore, the total increase in capacity is roughly 173%, or option d. 200%.