Short Line Application - ABB RELION 670 SERIES Applications Manual

Line distance protection

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1MRK 506 369-UUS -

Line distance protection REL670 2.2 ANSI

Application manual

loaded medium long lines. For short lines, the major concern is to get sufficient fault

resistance coverage and load encroachment is not a major problem. So, for short lines, the

load encroachment function could preferably be switched off. See section

impedance limitation, without load encroachment

The settings of the parameters for load encroachment are done in (21), FRPSPDIS (21)

Load impedance area in

ANSI05000495 V2 EN

Load encroachment phenomena and shaped load encroachment

characteristic defined in Phase selection and load encroachment

function (FRPSPDIS, 21)

Short line application

Transmission line lengths for protection application purposes are classified as short,

medium and long . The definition of short, medium and long lines is found in IEEE Std

C37.113-1999. ). The length classification is defined by the ratio of the source impedance

at the protected line's terminal to the protected line's impedance (SIR). SIR's of about 4

or greater generally define a short line. Medium lines are those with SIR's greater than 0.5

and less than 4

In short line applications, the major concern is to get sufficient fault resistance coverage.

Load encroachment is not so common. The line length that can be recognized as a short

line is not a fixed length; it depends on system parameters such as voltage and source

impedance, see table 19.

Typical length of short and very short line

Line category

Very short line

0.75 -3.5mile

forward direction

Impedance protection

ANSI05000495_2_en.vsd