IEEE 81.2-1991 IEEE Guide for Measurement of Impedance and Safety Characteristics of Large, Extended or Interconnected Grounding Systems

standard by IEEE, 06/25/1992

Full Description

Scope

Test methods and instrumentation techniques used to measure the ac characteristics of large grounding systemsinclude the following topics:1) Measurement safety2) Earth-return mutual errors3) Low-current measurements4) Power-system staged faults5) Communication and control cable transfer impedance6) Current distribution (current splits) in the grounding system7) Step, touch, mesh, and proA?le measurements8) The foot-equivalent electrode earth resistance9) Instrumentation characteristics and limitationsGrounding electrodes consisting of a single ground rod, arrays of ground rods, tower footings, and many grids (if noexternal grounding is connected) can be measured, interference voltages permitting, with methods outlined in IEEEStd 81-1983 [2]1. Even if a large grid has an impedance phase angle of 18¿¿the resistance component will be only 5%lower than its impedance. However, for large grounding grids in low-resistive earth (<75W-m) and for grounding systems that have numerous extended grounding conductors, the impedance could be signiA?cantly greater than theresistive component measured with the conventional test sets of IEEE Std 81-1983

Purpose

The purpose of this guide is to present practical instrumentation methods that may be used for the measurement ofimpedance to remote earth, step and touch potentials, and current distributions of large extended or interconnectedgrounding systems ranging in complexity from small grids (less than 900 m2), with only a few connected overhead ordirect burial bare concentric neutrals, to large grids (greater than 20 000 m2), with many connected neutrals, overheadground wires (sky wires), counterpoises, grid tie conductors, cable shields, and metallic pipes.

Abstract

New IEEE Standard - Inactive-Withdrawn.Practical instrumentation methods are presented for measuring the ac characteristics of large,extended or interconnected grounding systems. Measurements of impedance to remote earth, step andtouch potentials, and current distributions are covered for grounding systems ranging in complexity from small grids (less than 900m 2), with only a few connected overhead or direct burial bare concentric (2) neutrals, to large grids (greater than 20 000m 2), with many connected neutrals, overhead ground wires (sky wires), counterpoises, grid tie conductors, cable shields, and metallic pipes. This standard addresses measurement safety; earth-return mutual errors; low-current measurements; power-system staged faults; communication and control cable transfer impedance; current distribution (current splits) in the grounding system; step, touch, mesh, and profile measurements; the foot-equivalent electrode earth resistance; and instrumentation characteristics and limitations.

Product Details

Published: 06/25/1992 ISBN(s): 9780738106618 Number of Pages: 112 File Size: 1 file , 2.1 MB Product Code(s): STDWD14944