Figure. 5.4.18. - 78. If current transformer starpoints are pointing towards the same direction, “Subtract” differential calculation
mode is used.
Differential function has 2 separate stages inbuilt which of the non restraint uses only these formulas as
comparison base. For the restraint characteristics also so called “Bias” calculation is made per each
phase to adjust the sensitivity of the differential stage up to the measured currents.
For the bias calculation also two separate formulas are available.
Average mode (sensitive biasing):
Max mode (coarse biasing):
Now these two mentioned formulas are combined in a way so that the y axle presents the differential
current measured and the x axle present the bias current calculated.
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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