ABB RELION REX640 - 11.2.1.3 RI and RD-type inverse-time characteristics

t s
A
I
I
E
B k
c
[ ]
=
>






−
+












⋅
(Equation 394)
t[s] Operate time (in seconds)
A Set Curve parameter A
B Set Curve parameter B
C Set Curve parameter C
E Set Curve parameter E
I Measured current
I> Set Start value
k Set Time multiplier
11.2.1.3 RI and RD-type inverse-time characteristics
The RI-type simulates the behavior of electromechanical relays. The RD-type is an
earth-fault specific characteristic.
The RI-type is calculated using the formula
t s
k
I
I
[ ]
. .
=
− ×
>












0 339 0 236
(Equation 395)
The RD-type is calculated using the formula
t s
I
k I
[ ] . .= − ×
× >






5 8 1 35 In
(Equation 396)
t[s] Operate time (in seconds)
k Set Time multiplier
I Measured current
I> Set Start value
1MRS759142 F General function block features
REX640
Technical Manual
1881