ABB REL650 - Page 310

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 or functions, the auto-reclosing
open time is used to determine line “dead time”. When simultaneous tripping and
reclosing at the two line ends occurs, auto-reclosing open time is approximately equal to
the line “dead time”. If the open time and dead time differ then, the line will be energized
until the breakers at both ends have opened.
Open
Closed
Operate time
Line
protection
Circuit
breaker
Break time
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Fault duration
SMBRREC (79) open time for breaker
Fault duration
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Break timeClosing time
Operate time
F
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Set SMBRREC (79) open time Reset time
Auto-reclosing
function
I
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S
M
B
R
R
E
C
(
7
9
)
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(
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9
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ANSI11000166_1_en.vsd
ANSI11000166 V1 EN
Figure 136: Single-shot automatic reclosing at a permanent fault
Three-phase automatic reclosing can be performed with or without the use of a
synchronism check, and an energizing check, such as dead line or dead busbar check.
Section 11 1MRK 506 334-UUS A
Control
304
Application manual