•
Str 2 delay shot 2 = 60s
•
Str 2 delay shot 3 = 60s
Operation in a permanent fault:
1. Protection starts and activates the
DEL_INIT 2
input.
2. After 0.05 seconds, the first autoreclose shot is initiated. The function
opens the circuit breaker: the
OPEN_CB
output activates. The total trip
time is the protection start delay + 0.05 s the time it takes to
open the circuit breaker.
3. After the first shot, the circuit breaker is reclosed and the protection
starts again.
4. Because the delay of the second shot is 60 seconds, the protection is
faster and trips after the set operation time, activating the
INIT 2
input. The second shot is initiated.
5. After the second shot, the circuit breaker is reclosed and the protection
starts again.
6. Because the delay of the second shot is 60 seconds, the protection
is faster and trips after the set operation time. No further shots are
programmed after the final trip. The function is in lockout and the
sequence is considered unsuccessful.
Example 2
The delays can be used also for fast final trip. The conditions are the same
as in Example 1, with the exception of
Str 2 delay shot 3 = 0.10 seconds.
The operation in a permanent fault is the same as in Example 1, except that
after the second shot when the protection starts again,
Str 2 delay shot 3
elapses before the protection operate time and the final trip follows. The
total trip time is the protection start delay + 0.10 s the time it takes
to open the circuit breaker.
9.4.6.6
Fast trip in Switch on to fault
The
Str _ delay shot 4 parameter delays can also be used to achieve a fast
and accelerated trip with SOTF. This is done by setting the
Fourth delay in
SOTF parameter to "1" and connecting the protection start information to the
corresponding
DEL_INIT_
input.
When the function detects a closing of the circuit breaker, that is, any other closing
except the reclosing done by the function itself, it always prohibits shot initiation
for the time set with the
Reclaim time parameter. Furthermore, if the Fourth delay
in SOTF parameter is "1", the Str _ delay shot 4 parameter delays are also activated.
Example 1
The protection operation time is 0.5 seconds, the
Fourth delay in SOTF
parameter is set to "1" and the
Str 2 delay shot 4 parameter is 0.05 seconds.
The protection start signal is connected to the
DEL_INIT_2
input.
If the protection starts after the circuit breaker closes, the fast trip follows
after the set 0.05 seconds. The total trip time is the protection start delay +
0.05 s the time it takes to open the circuit breaker.
Control functions
1MRS757644 H
1038
620 series
Technical Manual
