ADR233B
Ref ID : ADR233B/IM/PS
Rev No. : 05
Page No. : 141 of 479
The over current, ground fault, Residual and sequence O/C function are programmable as per
IDMT characteristic based on IEC and IEEE/ANSI standards. The inverse time delay is
calculated with the following mathematical formula:
Where
t : Operation time
K : Constant (see the table)
I : Measured current
I
s
: Current threshold setting (also refer as Gs as IEC standard notation)
α : Constant (see the table)
L : ANSI/IEEE constant (zero for IEC curve)
T : Time multiplier setting (TMS) for IEC & IEEE curves
Description Standard K α L
Definite Time - - - -
IEC S Inverse IEC 0.14 0.02 0
ST Inverse 1.3S - 0.06 0.02 0
IEC V Inverse IEC 13.5 1 0
IEC E Inverse IEC 80 2 0
UK LT Inverse IEC 120 1 0
IEEE M Inverse IEEE 0.0515 0.02 0.114
IEEE V Inverse IEEE 19.61 2 0.491
IEEE Inverse IEEE 28.2 2 0.1217
US Inverse IEEE 5.95 2 0.18
US ST Inverse IEEE 0.0239 0.02 0.0169
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