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You can determine a limit value PROT1 max ERROR for the permissible rate of faulty protection data telegrams
under address 4513. This parameter can only be set in DIGSI at Display Additional Settings. The preset
value 1 % means that maximum one faulty telegram per 100 telegrams is permissible.
Protection data interface 2
If protection data interface 2 exists and is used, the same options as for protection data interface 1 apply. The
corresponding parameters are set at addresses 4601 STATE PROT I 2 (ON or OFF), 4602 CONNEC. 2 OVER,
4605 PROT 2 T-DELAYand 4606 PROT 2 UNSYM., the last two parameters can only be changed with DIGSI
under Additional Settings. If GPS synchronisation is available, the parameter is used at address 4611PI2
SYNCMODE. The maximum permissible rate of faulty protection data telegrams PROT2 max ERROR (address
4613) and the reaction to impermissible transmission time difference PI2 BLOCK UNSYM (address 4615)
(blocking the differential protection YES or NO) can be changed under Additional Settings.
GPS synchronisation (optional)
For the protection data interface, the synchronisation via GPS can be switched ON or OFF at address 4801
GPS-SYNC..
GPS synchronisation means the use of a 1-pulse-per-second signal (1 PPS). This signal is generated by an
external GPS receiver. The 1 PPS signal is connected to port A of the device (see Chapter 3, Table 3-12). The
1 PPS signal has the property that the leading edge presents a maximum deviation of 10 μs (compared
between 2 GPS receivers and under all GPS signal conditions). This feature does not depend on the location.
If the deviation of max. 10 μs is no longer ensured due to bad GPS receiving conditions, the 1 PPS signal must
be switched off by the GPS receiver.
In addition, these GPS receivers can provide further time signals, e.g. DCF77 or IRIG-B. These time signals
can be connected to port A as well. However, they are not suitable for a µs-accurate synchronisation of the
protection data interfaces and, consequently, of the differential protection. The edge accuracy of these time
signals is often insufficient.
At address 4803 TD GPS FAILD you can specify the time after which the indication „GPS loss" (no. 3247)
is output.
Other parameters concerning the GPS synchronisation can be set individually for each protection data interface
(see above).
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
2.2 Protection Data Interfaces and Protection Data Topology
Functions
87
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