Toshiba GRT100 Series Instruction Manual page 26

Setting of kct (1kct1-1kct3, 2kct1-2kct3 and 3kct1-3kct3)
CT ratio matching is performed between the line CT(s) and the neutral CT by setting 1kct1-1kct3
for 1REF element, 2kct1-2kct3 for 2REF element and 3kct1-3kct3 for 3REF element. The
settings are obtained as a ratio of the line CTs ratio to the neutral CT ratio and the line CTs have
the notations shown in the Appendix L according to 1REF to 3REF applications.
For example, the settings of 1kct1, 1kct2, 2kct1 and 2kct2 are calculated;
1kct1 = (CT ratio of line CT 1ct-1)/(CT ratio of neutral CT 1nCT)
1kct2 = (CT ratio of line CT 1ct-2)/(CT ratio of neutral CT 1nCT)
2kct1 = (CT ratio of line CT 2ct-1)/(CT ratio of neutral CT 2nCT)
2kct2 = (CT ratio of line CT 2ct-2)/(CT ratio of neutral CT 2nCT)
where,
CT ratio = (primary rated current)/(secondary rated current).
Setting of scheme switch [1REF] to [3REF]
[1REF] to [3REF] are set to "1I0", "2I0" or "3I0" when they introduce one, two or three line
currents respectively.
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6 F 2 S 0 7 8 9