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