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set value during the reset period, the operate calculations are continued using the
saved values. If the reset period elapses without a fault being detected, the operate
timer is reset and the saved values of start time and integration are cleared.
Inv. curve B
The inverse time equation for curve type B is:
t s
k
I
I
I
I
r
S
r
[ ]
=
−
2
2
2
(Equation 239)
t[s]
Operate time in seconds
k
Machine time Mult
I
2
Negative-sequence current
I
S
Set
Start value
I
r
Set
Rated current
Protection functions
1MRS759142 F
846
REX640
Technical Manual