3.5 EARTH FAULT PROTECTION
Measured
Pick-up (IDMT and DT) Setting +/-5%, or 20 mA, whichever is greater
Drop-off (IDMT and DT) > 0.95 x setting +/-5% or 20 mA, whichever is greater
Min. trip level (IDMT elements) 1.05 × Setting +/-5% or 10 mA, whichever is greater
IDMT characteristic shape
+/-5% or 40 ms, whichever is greater (under reference
conditions)
IEEE reset +/-5% or 40 ms, whichever is greater
DT operation +/-2% or 50 ms, whichever is greater
DT reset +/-2% or 50 ms, whichever is greater
Derived
IDMT pick-up 1.05 × Setting +/-5%
DT pick-up Setting +/-5%
Drop-off (IDMT and DT) 0.95 x setting +/-5%
IDMT operate +/-5% or 40 ms, whichever is greater
DT operate +/-2% or 50 ms, whichever is greater
DT reset Setting +/-5%
Overshoot of overcurrent elements <30 ms
3.6 TRANSIENT OVERREACH AND OVERSHOOT
Accuracy
Additional tolerance due to increasing X/R ratios +/-5% over the X/R ratio of 1 to 120
Overshoot of overcurrent elements < 40 ms
Disengagement time < 30 ms
MiCOM P747 Chapter 16 - Technical Specifications
P747-TM-EN-1 391
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