ABB RER620

1MAC309294-MB F Section 10
General function block features
RER620 521
Technical Manual
10.2.1.3 User-programmable inverse-time characteristics
The user can define curves by entering parameters into the following standard formula:
(Equation 59)
t[s] Trip time (in seconds)
A set
Curve parameter A
Bset Curve parameter B
C set Curve parameter C
Eset Curve parameter E
I Measured current
I> set
Pickup value
kset Time multiplier
10.2.1.4 RI and RD-type inverse-time characteristics
The RI-type simulates the behavior of electromechanical relays. The RD-type is a
ground-fault specific characteristic.
The RI-type is calculated using the formula
(Equation 60)
The RD-type is calculated using the formula
(Equation 61)
t[s] Trip time (in seconds)
kset
Time multiplier
I Measured current
I>set
Pickup value
ts
k
I
I
[]
..
=
−×
>
⎛
⎝
⎜
⎜
⎜
⎜
⎞
⎠
⎟
⎟
⎟
⎟
0 339 0 236
ts
I
kI
[] . .=− ×
×>
⎛
⎝
⎜
⎞
⎠
⎟
58 135 In