ABB Relion 670 series - Application

15.2.2 Application
Automatic reclosing is a well-established method for the restoration of service in a power
system after a transient line fault. The majority of line faults are flashovers, which are
transient by nature. When the power line is switched off by the operation of line protection
and line breakers, the arc de-ionizes and recovers its ability to withstand voltage at a
somewhat variable rate. Thus, a certain dead time with a de-energized line is necessary.
Line service can then be resumed by automatic reclosing of the line breakers. The dead
time selected should be long enough to ensure a high probability of arc de-ionization and
successful reclosing.
For individual line breakers, auto reclosing equipment, the required circuit breaker dead
time is used to determine the “dead time” setting value. When simultaneous tripping and
reclosing at the two line ends occurs, line dead time is approximately equal to the auto
recloser “dead time”. If the auto reclosing dead time and line “dead time” differ then, the
line will be energized until the breakers at both ends have opened.
en04000146_ansi.vsd
Open
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Operate time
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Circuit
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Break time
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Fault duration
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Break timeClosing time
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Auto-reclosing
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Reset time
ANSI04000146 V1 EN
Figure 307: Single-shot automatic reclosing at a permanent fault
Section 15 1MRK 506 369-UUS -
Control
654 Line distance protection REL670 2.2 ANSI
Application manual