Practical Power Plant Engineering

9Plant Power Distribution

CHAPTER MENU

• 9.1 Plant Overhead Distribution
  • 9.1.1 Introduction
  • 9.1.2 Line Construction Elements
• 9.2 Types of Distribution
  • 9.2.1 Line Design
• 9.3 Structure (Pole) Types
• 9.4 Overhead vs. Underground
• 9.5 Clearances
  • 9.5.1 Line to Roads
  • 9.5.2 Phase Clearances
• 9.6 Line Voltage Drop Calculations
• 9.7 Power Loss Calculations
• 9.8 Line Conductor Sag and Tension
• 9.9 Aerial Bundled Cable (ABC) Distribution
• 9.10 Line and Cable Charging Current
• References

9.1 Plant Overhead Distribution

9.1.1 Introduction

Each major industrial and power plant will require a spread‐out power distribution system to interconnect the large number of plant loads to the main switchyard and switchgear distribution boards, as shown in Figure 2.7. Overhead power distribution is classified in the electrical power industry by the voltage levels, as listed in the following. For the voltages used throughout the world (see Chapter 11).

1. Low voltage: Less than 1000 V; used for connections between residential or small commercial customers and the utility and within industrial facilities.
2. Distribution, medium voltage: Between 1000 V (1 kV) and to about 66 kV; used for distribution in urban and rural areas and industrial facilities.
3. Subtransmission: 66–115 kV,
4. Transmission, HV: Over 230 kV, up to about 800 kV; used for long distances.

The distribution lines (Figure 9.1) follow the most direct routes or along the roads to facilitate ease of construction and maintenance. Most of the countries ...