Transmission & Distribution Program

Introduction to Substation DesignTADP 542

Components

Instructor: Mike Nissley

Overview

Components

– This is a brief overview defining the components that make up a substation. The components will be covered in more detail during week 3 of the course.

Conductors

Materials or bodies capable of transmitting electricity.

Rated in amps at specific temperatures.

Figure 1: A sample 3 phase conductor

Insulators/Insulation

Very poor electrical conductors, or present high impedance to the flow of electricity.Insulation can be represented electrically as a circuit consisting primarily of small capacitors in series and parallel.Can be made of polymeric materials, glass, or porcelain.

Figure 2: An insulator.

Grounding Grid

Provides adequate personnel safety and an electrical environment that allows the expected functioning of electrical equipment.

An effective ground grid (see IEEE Std 80-2000, Guide for Safety in AC Substation Grounding) will facilitate the following:

Assure a level of personnel safety.Dissipate normal and fault currents to ground/earth.Provide a path for lighting impulses and switching surges. Provide low resistance for protective relay circuits.

Direct Current (DC) Power System

The DC system consists of: battery, battery charger, monitoring, control devices, and a distribution system.

125V substation battery

Alternating Current Power System

A low voltage AC distribution system is required to provide power for the DC System and other auxiliaries.

Control System

Devices and circuits used to intentionally control system equipment.

Protective Relaying Systems

Protective relays detect abnormal electrical conditions and initiate preprogrammed corrective actions.

Figure 3: Protective relay block diagram

Instrument Transformers

Reproduce primary voltage and current in secondary circuits with phase relationship substantially preserved.

Referred to as potential transformer (PT) and current transformer (CT).

Figure 4: A small current transformer (CT)

Supervisory Control and Data Acquisition (SCADA)

SCADA systems primarily facilitate remote operation of a system of distributed devices.

The SCADA system is comprised of main equipment at a control center and remote terminal units.

Supervisory Control and Data Acquisition (cont.)

Figure 5: A representation of SCADA

Automation (Integration) Systems

Use of computers and communication devices to optimize system operation and facilitate remote control and monitoring.

Usually includes SCADA functionality along with extended monitoring and control capabilities.

Image Acknowledgements

Conductor– http://www.alertelectrical.com/files/cable6944xlh.jpg

Insulator– http://www.vnemart.com.vn/Images/Products/Dead%20end%20insulator.jpg

Protective Relay– http://www.freepatentsonline.com/7123459-0-large.jpg

Current Transformer– http://electricalplan.blogspot.com/2008_04_01_archive.html

SCADA– http://www.wastechengineering.com/images/SCADA.gif