IEEE 81-2012 pdf download IEEE Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Grounding System
1.2 Purpose
The purpose of this guide is to present practical instrumentation methods that may be used formeasuring soil resistivity, the impedance to remote earth, step and touch voltages, and currentdistributions in ground grids associated with electric utility facilities. These grids typically consist ofinterconnected grounding systems ranging in complexity from a few ground rods to large grids withmany ground rods or wells, buried conductors, and external ground connections. External groundconnections may include overhead shield/ground/neutral wires, underground cable sheaths/neutrals.counterpoises, grid tie conductors, metallic pipes, and other connections that provide additional paths toremote earth.
This guide is intended to assist the engineer or technician in obtaining and interpreting accurate, reliabledata. 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 mmeasurementthe 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 ofpersonnel and property, and it seeks to minimize operating interferences with neighboring facilities.
2.Normative references
The following referenced document is indispensable for the application of this document (i.e., it must beunderstood and used, so each referenced document is cited in text and its relationship to this documentis explained). For dated references, only the edition cited applies. For undated references, the latestedition of the referenced document (including any amendments or corrigenda) applies.
IEEE Std 80mIEEE Guide for Safety in AC Substation Grounding.
3.Definitions
For the purposes of this document, the following terms and definitions apply. The IEEE StandardsDictionary Online should be consulted for terms not defined in this clause.
apparent soil resistivity: The equivalent, overall resistivity of a volume of soil with varying propertiesbonding: The electrical interconnecting of conductive parts, designed to maintain a common electricapotential.
counterpoise (overhead lines) (lightning protection): A conductor or system of conductors. typicallyarranged beneath a transmission or distribution line, located most frequently below the surface of theearth and connected to the grounding system of towers or poles supporting the line.coupling: The association of two or more circuits or systemms in such a way that power or signalinformation is transferred from one to another.
electric potential difference: The potential energy per unit charge between two points in an electricfield
equipotential line or contour: The locus of points having the same potential at a given time.ground: A conducting connection, whether intentional or accidental, by which an electric circuit orequipment is connected to the earth, or to some conducting body of relatively large extent that serves inplace of the earth.