Full Description
Scope
The test methods and techniques used to measure the electrical characteristics of the grounding system include the following topics:a) Establishing safe testing conditionsb) Measuring earth resistivityc) Measuring the power system frequency resistance or impedance of the ground system to remote earthd) Measuring the transient (surge) impedance of the ground system to remote earthe) Measuring step and touch voltagesf) Verifying the integrity of the grounding systemg) Reviewing common methods and procedures for performing ground testingh) Reviewing instrumentation characteristics and limitationsi) Reviewing various factors that can distort test measurements
Purpose
The purpose of this guide is to present practical instrumentation methods that may be used for measuring soil resistivity, the impedance to remote earth, step and touch voltages, and current distributions in ground grids associated with electric utility facilities. These grids typically consist of interconnected grounding systems ranging in complexity from a few ground rods to large grids with many ground rods or wells, buried conductors, and external ground connections. External ground connections may include overhead shield/ground/neutral wires, underground cable sheaths/neutrals, counterpoises, grid tie conductors, metallic pipes, and other connections that provide additional paths to remote earth.This guide is intended to assist the engineer or technician in obtaining and interpreting accurate, reliable data. The factors that influence the choice of instruments are discussed along with a presentation of fieldtechniques for various types of measurements. These factors include the purpose of the measurement, the accuracy required, the types of instruments available, the possible sources of error, and the nature ofthe ground or grounding system under test. It also describes test procedures that promote the safety of personnel and property, and it seeks to minimize operating interferences with neighboring facilities.
Abstract
Revision Standard - Active.Practical test methods and techniques are presented for measuring the electrical characteristics of grounding systems. Topics addressed include safety considerations, measuring earth resistivity, measuring the power system frequency resistance or impedance of the ground system to remote earth, measuring the transient or surge impedance of the ground system to remote earth, measuring step and touch voltages, verifying the integrity of the grounding system, reviewing common methods for performing ground testing, reviewing instrumentation characteristics and limitations, and reviewing various factors that can distort test measurements.
