Hitachi Relion 670 Series Applications Manual page 217

1MRK506375-UEN Rev. N
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.
Line
protection
Operate time
Circuit
breaker
Auto-reclosing
function
IEC04000146 V3 EN-US
Figure 77:
Automatic reclosing can be performed with or without the use of synchrocheck.
For the individual line breakers and auto reclosing equipment, the auto reclosing dead time
expression is used. This is the dead time setting for the auto recloser. During simultaneous tripping
and reclosing at the two line ends, auto reclosing dead time is approximately equal to the line dead
time. Otherwise these two times may differ as one line end might have a slower trip than the other
end which means that the line will not be dead until both ends have opened.
If the fault is permanent, the line protection will trip again when reclosing is attempted in order to
clear the fault.
It is common to use one automatic reclosing function per line circuit breaker (CB). When one CB per
line end is used, then there is one auto- recloser per line end. If auto reclosers are included in
duplicated line protection, which means two auto reclosers per CB, one should take measures to
avoid uncoordinated reclosing commands.
The auto recloser can be selected to perform multiple shots. The auto reclosing dead time can be set
to give either High-Speed Automatic Reclosing (HSAR) or Delayed Automatic Reclosing (DAR).
HSAR usually means a dead time of less than 1 second.
The mode of automatic reclosing varies. Single-shot and multi-shot are in use. The first shot can
have a short delay, HSAR, or a longer delay, DAR. The second and following reclosing shots have a
rather long delay. When multiple shots are used the dead time must harmonize with the breaker duty-
cycle capacity.
Railway application RER670
Application manual
Closed
Open
Break time
Fault duration
Set AR dead time
Single-shot automatic reclosing at a permanent fault
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Operate time
Closing time
Circuit breaker open time Fault duration
Reclaim time
Break time
IEC04000146-3-en.vsd
Section 12
Control
211