ABB RELION REX640 Technical Manual page 846

Protection functions
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
t[s]
k
I
2
I
S
I
r
846
k
=
2 2
   
I I
 − S
2
  
I I
   
r r
Operate time in seconds
Machine time Mult
Negative-sequence current
Set Start value
Rated current
Set
1MRS759142 F
(Equation 239)
REX640
Technical Manual