---
title: "Define primary distribution"
subject: "Transmission and Distribution System Design"
chapter: 5
key: "semester_8/transmission_and_distribution_system_design:define-primary-distribution"
source: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/define-primary-distribution
site: BCT Engineering
---

# Define primary distribution

Transmission and Distribution System Design · Chapter 5: Electric Power Distribution

- Asked in: 2080 Chaitra, 1 marks
- Video: [Primary distribution system: Radial system, ring main system and interconnected network system.](https://www.youtube.com/watch?v=J_K4GrrITP0) — SKP Electronics
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/define-primary-distribution
- Whole chapter: https://www.bctengineer.com/md/semester_8/transmission_and_distribution_system_design/chapter-5

## Question

With respect to a distribution system, define primary distribution.

## Short answer

Primary distribution operates at medium voltage (33 kV and 11 kV in Nepal) and carries power from grid substations to distribution transformers or large consumers. It consists of three-phase, three-wire primary feeders and laterals, typically radial or open-loop.

## Answer

**Primary distribution** is the part of the distribution system that operates at **medium voltage**: 33 kV and 11 kV in Nepal. It carries power from the distribution (grid) substation to the distribution transformers, or directly to large consumers such as industries.

It consists of the primary feeders and laterals, which are usually three-phase, three-wire and mostly radial or open-loop.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. At what voltage is primary distribution in Nepal?
   A. 400 V
   B. 33 kV and 11 kV
   C. 230 V
   D. 220 kV
   Answer: B. It is medium voltage. (Key point: Voltage level)

2. What does it connect?
   A. Transformers to houses
   B. Generator to grid
   C. Distribution substation to distribution transformers or large consumers
   D. Consumers to meters
   Answer: C. It carries power from the grid substation onward. (Key point: Extent)

3. How is it usually arranged?
   A. Single-phase
   B. Three-phase, three-wire, mostly radial or open-loop
   C. Four-wire LT
   D. Network only
   Answer: B. Primary feeders and laterals are three-phase three-wire. (Key point: Configuration)

## Related in Transmission and Distribution System Design

- [T/F: higher primary voltage in rural distribution](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Atf-rural-higher-primary-voltage) — Transmission and Distribution System Design, chapter 7, asked 2×
- [Radial vs loop distribution system](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Aradial-vs-loop-distribution) — Transmission and Distribution System Design, chapter 5, asked 2×
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