Siemens siprotec 7SA522, Руководство пользователя

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Functions
6-94
7SA522 Manual
C53000-G1176-C119-2
effect on the receive circuit of the teleprotection; conversely the permissive signal is
not delayed by the set time delay T1B of the overreaching zone Z1B.
Transient Blocking The parameters
7U%ON:DLW7LPH
and
7U%ON%ORFN7LPH
serve the transient
blocking with the permissive overreaching schemes PUTT and UNBLOCKING. With
permissive underreach transfer trip they are of no consequence. This setting can only
be modified with DIGSI
®
4 under “Additional Settings”.
The time
7U%ON:DLW7LPH
(address ) is a waiting time before transient block-
ing. Only once the distance protection recognizes a reverse fault inside this time after
fault detection, will the transient blocking become activated in the permissive over-
reach transfer schemes. With the blocking scheme this waiting time prevents a tran-
sient blocking if the blocking signal from the opposite line end is received very rapidly.
There is no transient blocking with the setting
∞
.
The transient blocking time
7U%ON%ORFN7LPH
(address ) must be definitely
longer than the duration of severe transients resulting from the inception or clearance
of external short circuits. The send signal is delayed by this time with the permissive
overreach schemes
3277
and
8QEORFNLQJ
if the protection had initially detected a
reverse fault. With the blocking scheme
%ORFNLQJ
the (blocking) receive signal is
prolonged by this time.
The preset value is generally sufficient.
Echo Function In the case of line ends with weak infeed, the echo function is sensible in conjunction
with permissive overreach transfer schemes POTT and UNBLOCKING with release
signal, so that the feeding line end is also released. The echo function can be enabled
under address
)&7:HDN,QIHHG
(
(&+2RQO\
) or disabled (
2))
). With this
“switch” the weak infeed tripping function can also be activated (
(&+2DQG75,3
,
refer also to Section 6.7).
The notes regarding the setting of the distance stages above, and the margin head-
ings “Distance Protection Prerequisites” must in any event be noted.
The echo delay time
7ULS(FKR'(/$<
(address ) must be set long enough to
avoid incorrect echo signals resulting from the difference in fault detection pick-up time
of the distance protection functions at the two line ends during external faults (through-
fault current). A typical setting is approximately 40 ms (presetting). This setting can
only be modified with DIGSI
®
4 under “Additional Settings”.
The echo impulse duration
7ULS(;7(16,21
(address ) can be set to adapt to
the circumstances of the signal transmission equipment. It must be long enough to en-
sure that the receive signal is recognized even with different pick-up times by the pro-
tection devices at the line ends and different response times of the transmission equip-
ment. Generally a setting of approximately 50 ms (presetting) is sufficient. This setting
can only be modified with DIGSI
®
4 under “Additional Settings”.
The setting for the echo function is the same for all measures taken against weak in-
feed and summarised in tabular form in Section 6.7.