Siemens siprotec 7SA6 - Page 312

Functions
6-130 7SA6 Manual
C53000-G1176-C133-1
circuit breaker at the non-feeding line end is open, this delay of the echo signal is not
required. The echo delay time may then be bypassed. The circuit breaker switching
state is provided by the central information function control. (refer to Section 6.20).
The echo impulse is then transmitted (alarm output “(&+26,*1$/”), the duration of
which can be set with the parameter 7ULS(;7(16,21.
After transmission of the echo impulse, the transmission of a new echo is prevented
for at least 20 ms. This prevents from repetition of an echo after the line has been
switched off.
The echo function is not required for the blocking scheme, and is therefore ineffective.
Figure 6-78 Logic diagram of the echo function for the earth fault protection with teleprotection
Note:
The “(&+26,*1$/” (F.No. 4246) must be separately assigned to the output relay
that is used for signal transmission, as it is not included in the transmit signal
“()7HOH6(1'”.
20 0
T
EF Pickup
&
S
R
Q
from receiving logic
(Fig. 6-72 or 6-74)
EF OFF/BLOCK
I
E
3I
0
 ,R0LQ7HOHSURW
≥1
&
>EF BlkEcho

ECHO only
OFF
ECHO and TRIP
„1“
≥1
≥1
 7LPH'(/$<
0
T
 7ULS(;7(16,21
&
Echo release by
the distance prot.
(ref. to Fig. 6-59
&
CB open (3pole)
≥1
&
S
R
Q
ECHO SIGNAL
1324
ms
4246
)&7:HDN,QIHHG