2.2 Protection Data Interfaces and Protection Data Topology
81
7SD5 Manual
C53000-G1176-C169-1
2.2.2 Protection Data Interfaces
2.2.2.1 Setting Notes
General
Information about
Interfaces
The protection data interfaces connect the devices with the communication media.
The communication is permanently monitored by the devices. Address 4509 T-DATA
DISTURB defines after which delay time the user is informed about a faulty or missing
telegram. Address 4510 T-DATAFAIL is used to set the time after which a transmis-
sion failure alarm is output. Address 4512 Td ResetRemote determines how long
time remote information remains standing after a transmission fault has been cleared.
Protection Data
Interface 1
The protection data interface 1 can be turned ON or OFF in address 4501 STATE PROT
I 1. If it is switched OFF, this corresponds to a transmission failure. In case of a ring
topology, the differential protection and all functions which require the transmission of
data, can continue their operation, but not in case of a chain topology.
In address 4502 CONNEC. 1 OVER, set the transmission media that you want to
connect to protection data interface PI 1. The following selection is possible:
F.optic direct, i.e. communication directly by fibre-optic cable with 512 kBit/s;
Com conv 64 kB, i.e. via communication converters with 64 kBit/s (G703.1 or X.21or
S0);
Com conv 128 kB, i.e. via communication converters with 128 kBit/s (X.21, copper
cable);
Com conv 512 kB i.e. via communication converter 512 kbit/s (X.21).
The possibilities may vary for the different device versions. The data must be identical
at both ends of a communication route.
The setting depends on the features of the communication media. As a general rule,
it can be stated that the higher the transmission rate the shorter the tripping time of the
differential protection system.
The devices measure and monitor the transmission times. Deviations are corrected,
as long as they are within the permissible range. These permissible ranges are set
under addresses 4505 and 4506 and can normally be left at their default values.
The maximum permissible transmission time (address 4505 PROT 1 T-DELAY) is
preset to a value that does not exceed the usual delay of communication networks.
This parameter can only be altered with DIGSI
®
under Additional Settings. If it is ex-
ceeded during operation (e.g. because of switchover to a different transmission route),
the message „PI1 TD alarm“ (No. 3239) will be issued. Increased transmission
times only have an impact on the tripping time of the differential protection system.
The maximum transmission time difference (outgoing telegram vs. return telegram)
can be altered in address 4506 PROT 1 UNSYM.. This parameter can only be altered
with DIGSI
®
under Additional Settings. With a direct fibre-optic connection, this value
can be set to 0. For transmission via communication networks a higher value is
needed. The standard value is 100 µs (default setting). The permissible transmission
time difference has a direct influence on the sensitivity of the differential protection.
If GPS synchronization is used this value is relevant only in case the GPS signal is
missing. As soon as the GPS synchronization is restored, the transmission time differ-
ences are compensated again. As long as GPS synchronization is intact, transmission
time differences do not affect the sensitivity of the protection.
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