Toshiba GR200 Series - 2.32.1 FL calculation with data at a local-terminal and remote-terminals

6F2S1914 (0.49)
GRL200 (Soft 033 & 037)
- 379 -
2.32.1 FL calculation with data at a local-terminal and remote-terminals
When considering the FL calculation with data at a local-terminal and remote-terminals , user
should note the computation requires minimum two-cycles of fault continuing time. The FL
result includes calculation errors: fixed error and proportional error. The fixed error is because
of the arithmetic error, but the proportional error is because of the settings in Segregated-
current-differential protection
1
(DIFL) function. The proportional error corresponds to the
setting
2
[DIFL-I1], but this error is inversely proportional to the differential current
2
(Id).
The FL calculation requires data of voltages and currents at a local-terminal and remote-
terminals. The FL does not calculate for a switch-onto-fault or for a fault when the line
energizes from one terminal and the other terminal is out-of-service.
When user considers the FL calculation in three-terminal application, if one of the three-
terminal is out-of-service, and when a fault arises between the junction and the out-of-service
terminal, the FL calculation assumes this fault being at the junction.
1
Note: For more information of the DIFL, see Chapter Relay application: Segregated
current differential protection
2
Note: Setting [DIFL-I1] and differential current (Id) are discussed in the DIFL.