2.16 Synchronism and Voltage Check (optional)
317
7SD5 Manual
C53000-G1176-C169-1
an automatic reclose attempt dead line conditions are only checked at one line end
and after the automatic reclose attempt only synchronism at the other end.
Dead-line or dead-
bus Closing
To release the closing command to couple a dead overhead line to a live busbar, the
following conditions are checked:
• Does the feeder voltage U
Line
lie below the set value
Dead Volt. Thr.
?
• Does the busbar voltage U
Bus
lie above the set value
Live Volt. Thr.
, but below
the maximum operating voltage
Umax
?
• Is the frequency f
bus
within the permitted operating range f
N
±
3 Hz?
After successful check the closing command is released.
Corresponding conditions apply when switching a live line onto a dead busbar or a
dead line onto a dead busbar.
Closing under syn-
chronous sytem
conditions
Before releasing a closing command at synchronous conditions, the following condi-
tions are checked:
• Does the busbar voltage U
Bus
lie above the set value
Live Volt. Thr.
, but below
the maximum operating voltage
Umax
?
• Does the feeder voltage U
Line
lie above the set value
Live Volt. Thr.
, but below
the maximum operating voltage
Umax
?
• Is the angle difference |U
Line
– U
Bus
| within the permissible tolerance
Max. Volt.
Diff
?
• Are the two frequencies f
1bus
and f
line
within the permitted operating range f
N
±
3 Hz?
• Does the frequency difference |f
line
– f
bus
| lie within the permissible tolerance
Max.
Freq. Diff
?
• Is the angle difference |
ϕ
line
–
ϕ
bus
| within the permissible tolerance
Max. Angle
Diff
?
To check whether these conditions are observed for a certain minimum time, you can
set this minimum time as
T SYNC-STAB
. Checking the synchronism conditions can
also be confined to a maximum monitoring time
T-SYN. DURATION
. This implies that
the conditions must be fulfilled within the time
T-SYN. DURATION
for the duration of
T SYNC-STAB
. If this is the case, the closing command is released.
Closing under
Asynchronous
System Conditions
Before releasing a closing command at asynchronous conditions, the following condi-
tions are checked:
• Does the busbar voltage U
Bus
lie above the set value
Live Volt. Thr.
, but below
the maximum operating voltage
Umax
?
• Does the feeder voltage U
Line
lie above the set value
Live Volt. Thr.
, but below
the maximum operating voltage
Umax
?
• Is the angle difference |U
Line
– U
Bus
| within the permissible tolerance
Max. Volt.
Diff
?
• Are the two frequencies f
bus
and f
line
within the permitted operating range f
N
±
3 Hz?
• Does the frequency difference |f
line
– f
bus
| lie within the permissible tolerance
Max.
Freq. Diff
?
When the check has been terminated successfully, the device determines the next
synchronizing time from the angle difference and the frequency difference. The close
command is issued at synchronization time minus the operating time of the circuit
breaker.
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