11.2.1.2 User-programmable inverse-time characteristics
The user can define curves by entering parameters into the following standard
formula:
A060641 V2 EN (Equation 100)
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
[ ]
. .
=
− ×
>

ï£










0 339 0 236
A060642 V2 EN (Equation 101)
The RD-type is calculated using the formula
t s
I
k I
[ ] . .= − ×
× >

ï£




5 8 1 35 In
A060643 V2 EN (Equation 102)
1YHT530004D05 D Section 11
General function block features
615 series 813
Technical Manual