ABB Relion 611 Series, Technical Manual

Page: 467 / 536

9.2.1.2 User-programmable inverse-time characteristics
The user can define curves by entering parameters into the following standard
formula:
t s
A
I
I
E
B k
c
[ ]
=
>





 −
+












⋅
A060641 V3 EN
(Equation 41)
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
9.2.1.3 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
A060642 V2 EN
(Equation 42)
The RD-type is calculated using the formula
t s
I
k I
[ ] . .
= − ×
× >






5 8 1 35 In
A060643 V2 EN
(Equation 43)
1MRS757454 D
Section 9
General function block features
611 series 461
Technical Manual