Siemens siprotec 7SA522, User Manual

Page: 267 / 628

Functions
6-119
7SA522 Manual
C53000-G1176-C119-2
allel lines, is neutralized by the “Transient Blocking”. It prolongs the blocking signal by
the transient blocking time
7U%ON%ORFN7LPH
(address ), if it has been present
for the minimum duration equal to the waiting time
7U%ON:DLW7LPH
(address
).
It lies in the nature of the blocking scheme that earth faults with single sided infeed can
be rapidly cleared without any special measures, as the non feeding end does not gen-
erate a blocking signal.
On three terminal lines, the transmit signal is sent to both opposite line ends. The re-
ceive signal is then combined with a logical
OR gate as no blocking signal must be
received from any line end during an internal fault. With the setting parameter
/LQH
&RQILJ
(address ) the device is informed as to whether it has one or two op-
posite line ends.
Figure 6-70 Logic diagram of the blocking scheme (one line end)
6.6.1.4 Transient Blocking
Transient blocking provides additional security against erroneous signals due to tran-
sients caused by clearance of an external fault or by fault direction reversal during
clearance of a fault on a parallel line.
The principle of transient blocking scheme is that following the incidence of an external
fault, the formation of a release signal is prevented for a certain (settable) time. In the
3IoMin Teleprot
6HQG3URORQJ
&
T 0
≥
1
I
L1
, I
L2
, I
L3
d
dt
40 ms
(u,i)
(A)
U
L1
, U
L2
, U
L3
EF forward
&
&
EF Pickup
3208
79
0 T
/LQH&RQILJ
Two terminals
Three terminals
EF Enable Trip
7U%ON:DLW7LPH
T T
7U%ON%ORFN7LPH
&
≥
1
&
&
&
EF Telep. off
1313 >EF TeleprotBLK
EF TeleTransBlk
1318 >EF Rec.Ch1
1319 >EF Rec.Ch2
EF Telep. OFF
1381
EF Tele SEND 1384
EF Tele BL STOP
1384
EF TeleTransBlk
1386
EF Tele BL Jump
1390