ABB Relion 611 Series, Technical Manual

Page: 253 / 536

When the reset period is initiated, the time for which
START
has been active is saved.
If the fault reoccurs, that is, the negative-sequence current rises above the 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
GUID-805DCB50-71D2-4721-830B-3343E1A5500B V1 EN
(Equation 28)
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
1MRS757454 D
Section 4
Protection functions
611 series 247
Technical Manual