Economical Distribution System

Introduction:
The distribution system is the final stage of power delivery from the power plant to the end-users. The efficiency and cost of the distribution system significantly impact the overall power delivery cost. Therefore, choosing an economical distribution system is crucial for power utilities.

Options:
The given options are:
a) Single phase AC system
b) DC system
c) Three phase, 4-wire AC system
d) Three phase, 3-wire AC system

Explanation:
The most economical distribution system is the one that has low installation cost, low maintenance cost, and high efficiency. Let's evaluate each option based on these criteria.

a) Single phase AC system: It has low installation cost, but it is inefficient, and the maintenance cost is relatively high. Therefore, it is not the most economical option.

b) DC system: It has low installation cost, high efficiency, and low maintenance cost. Moreover, it is suitable for various applications, including renewable energy integration, electric vehicles, and data centers. Therefore, it is the most economical option.

c) Three phase, 4-wire AC system: It has high installation and maintenance costs, and its efficiency is relatively low. Therefore, it is not the most economical option.

d) Three phase, 3-wire AC system: It has a similar installation and maintenance cost as the 4-wire system, and its efficiency is slightly better. However, it is not as efficient as the DC system. Therefore, it is not the most economical option.

Conclusion:
The most economical distribution system is the DC system due to its low installation cost, high efficiency, and low maintenance cost.