Question

In India the primary transmission of electric power is carried through

• A. 3-phase, 1 wire
• B. 1-phase, 3 wire
• C. 1-phase, 1 wire
• D. 3-phase, 3 wire

Hint:

Remember: Transmission is balanced, so no neutral wire is needed (3-wire).
Distribution is unbalanced, so a neutral wire is necessary (4-wire).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Power transmission systems are designed to carry massive electrical power over long distances efficiently while minimizing conductor costs.

Step 3: Detailed Explanation:
Primary transmission systems in India use high-voltage three-phase alternating current.
Under balanced operating conditions, the sum of the currents in the three phases is zero.
This eliminates the need for a neutral return conductor during long-distance transmission.
Therefore, primary transmission is conducted using a 3-phase, 3-wire system to optimize conductor weight and cost.
In contrast, distribution systems utilize a 3-phase, 4-wire system to provide a neutral path for single-phase residential consumers.

Step 4: Final Answer:
The correct option is 4, which corresponds to 3-phase, 3 wire.