2 Functions
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7SD610 Manual
C53000-G1176-C145-4
exchange of information between several differential protection systems (thus also for
several protected objects) can be executed via the same communication system.
If you work with different physical interfaces and communications links, please make
sure that every protection data interface corresponds to the projected communication
link.
For a protected object with two ends (e.g. a line) the addresses 4701 ID OF RELAY
1 and 4702 ID OF RELAY 2 are set, e.g. for device 1 the device-ID 16 and for device
2 the device-ID 17 (Figure 2-14). The indices of the devices and the device-IDs do not
have to match here, as mentioned above.
Figure 2-14 Differential protection topology for 2 ends with 2 devices — example
In address 4710 LOCAL RELAY you indicate the actual local device. One device has
index 1, the other index 2.
Make sure that the parameters of the differential protection topology for the differential
protection system are conclusive:
• Each device index can only be used once.
• Each device index must be assigned unambiguously to one device ID.
• Each device index must be the index of a local device once.
• The device with index 1 is the source for the absolute time management (timing
master).
During startup of the protection system, the above listed conditions are checked. If one
out of these conditions is still not fulfilled, no differential protection operation is possi-
ble.
The device then issues one of the following error messages
• „DT inconsistent“ (Device Table contains two or more identical device ident
numbers)
• „DT unequal“ (Different settings of parameters 4701 to 4702)
• „Equal IDs“ (Protection system contains devices with identical settings of pa-
rameter 4710)
If the indication „Par. different“ ON is displayed, the differential protection is
blocked as well. In this case the following parameters, which should have identical set-
tings in the devices, have in fact different settings.
•Address 230 Rated Frequency
•Address 143 TRANSFORMER in the protected zone
•Address 1106 OPERATION POWER primary
•Address 112 DIFF.PROTECTION exists
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