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In address 4710 LOCAL RELAY you indicate the actual local device. Enter the index for each device (according
to the consecutive numbering used). Each index from 1 to the entire number of devices must be used once,
but may not be used twice.
Figure 2-21
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).
• The number of configured devices must be identical in all devices.
During startup of the protection system, the above listed conditions are checked. If one of these conditions is
not yet fulfilled, the differential protection does not operate.
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 4706)
• „Equal IDs" (Protection system contains devices with identical settings of parameter 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 settings in the devices, have in fact different settings.
• Address 230 Rated Frequency
• Address 143 TRANSFORMER in the protected zone
• Address 1104 FullScaleCurr.
• Parameter 1106 OPERATION POWER primary parameter 1106 is only displayed if parameter 143 is set to
yes
• Address 112 DIFF.PROTECTION exists
• Address 149 charge I comp. exists
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
Differential protection topology for 4 ends with 4 devices — example
2.2 Protection Data Interfaces and Protection Data Topology
Functions
91
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