Siemens 7SR18 Solkor Manual page 313

7SR18 Commissioning & Maintenance Guide
Figure 2.3-1 Loop Test Mode
c) Line Test Mode
If the communications path exists and both relays are capable of being powered up, this method may be used.
The communications channel can be checked by assigning a LED to the 'Prot'n Comms In Sync' signal in the
Output Matrix. It will remain illuminated if it is in a healthy state. If an end to end communications problem exists,
the LED will extinguish.
Connect relays at either end to the communications channel.
Set the relay required to be tested into 'Line Test' mode, via the PROT'N COMMS menu. Only one relay must be
put in 'Line Test' mode at a time as this enables a complete test of the signal path from one end of the feeder.
To select this mode, press the [Down] arrow button on the relay until the PROT'N COMMS appears, then press
[Right] arrow button on the relay until the PROTECTION COMMS appears, then press the [Down] arrows until
Prot'n Test Mode appears. Press [Enter] and then use [Up] / [Down] arrows to select 'Line Test' and press
[ENTER] to confirm.
The relay in 'Line Test' mode can now be tested as in the 'Loop Test' mode i.e. injection will simulate a single end
fed fault. The pickup and drop-off accuracy of the differential elements of the relay in 'Line Test' can be performed
in a similar way to the 'Loop Test' above. Only the relay injected will operate for that level.
Figure 2.3-2 Line Test Mode
Secondary testing of the bias characteristic will be greatly simplified by the use of automated numeric protection
test equipment such as the Omicron CMC256. This equipment can be programmed using settings which match
those of the relay, to test for accuracy over the whole operating range and give a clear easy to use graphical
display of relay performance against the specified characteristic.
During manual testing the Operate and Restrain currents can be monitored on the relay in the Differential Meters
in the Instruments menu.
For manual testing, the bias slope is usually checked for Restrain current up to 250 % of nominal current. For
testing above this level the continuous current rating of the relay inputs is likely to be exceeded, equipment or test
procedure should be arranged in such a way that the short term thermal withstand of the relay current inputs is
not exceeded during testing.
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