ABB REL 551 2.3 Series Installation And Comissioning Manual page 96

90
Definite and inverse time-delayed
residual overcurrent protection (TEF)
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Normal inverse
t
Very inverse
t
Extremely inverse
t
Logarithmic inverse
t
Where:
I is a multiple of set current 3I
k is a time multiplying factor, settable in the range of 0.05 to 1.10
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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0.14
------------------- - k ⋅
=
0.02
I 1
–
13.5
---- ------- k ⋅
=
I 1
–
80
------------- k ⋅
=
2
I 1
–
( ⋅ )
= 5.8 – 1.35 ln I
>
0
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(Equation 1)
(Equation 2)
(Equation 3)
(Equation 4)