ABB REL 551 2.3 Series - Page 96

90
Definite and inverse time-delayed
residual overcurrent protection (TEF)
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Also check the tMin (minimum operate time) and IMin (minimum
operate current) functions.
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No TEF--TRIP nor TEF--START signal should appear.
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Normal inverse
(Equation 1)
Very inverse
(Equation 2)
Extremely inverse
(Equation 3)
Logarithmic inverse
(Equation 4)
Where:
I is a multiple of set current 3I
0
>
k is a time multiplying factor, settable in the range of 0.05 to 1.10
t
0.14
I
0.02
1–
--------------------
k
⋅=
t
13.5
I1–
-----------
k
⋅=
t
80
I
2
1–
-------------
k
⋅=
t 5.8 1.35
I
ln⋅()–=