ABB Relion 620 Series - Page 1141

t s
A
I
I
E
B k
c
[ ]
=
>






−
+












⋅
(Equation 196)
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 197)
The RD-type is calculated using the formula
t s
I
k I
[ ] . .= − ×
× >






5 8 1 35 In
(Equation 198)
t[s] Operate time (in seconds)
k set Time multiplier
I Measured current
I> set Start value
1MRS757644 H General function block features
620 series
Technical Manual
1141