ABB RELION 611 Series Technical Manual page 253

1MRS757454 D
611 series
Technical Manual
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:
k
t s
[ ]
=
2 2
I
I
   
2 S
 −
  
I I
r r
   
GUID-805DCB50-71D2-4721-830B-3343E1A5500B V1 EN
t[s] Operate time in seconds
Machine time Mult
k
I Negative-sequence current
2
Start value
I Set
S
I Set Rated current
r
Section 4
Protection functions
(Equation 28)
247