ABB RER620

Section 10 1MAC309294-MB F
General function block features
542 RER620
Technical Manual
The Minimum trip time setting defines the minimum trip time possible for the IDMT mode.
For setting a value for this parameter, the user should carefully study the particular IDMT
curve.
10.3.2.1 Standard inverse-time characteristics for undervoltage protection
The trip times for the standard undervoltage IDMT curves are defined with the coefficients
A, B, C, D and E.
The inverse trip time can be calculated with the formula:
(Equation 66)
t [s] trip time in seconds
V measured voltage
V< the set value of the
Pickup value setting
k the set value of the
Time multiplier setting
Table 426: Curve coefficients for standard undervoltage IDMT curves
Curve name A B C D E
(21) Inverse
Curve A
11001
(22) Inverse
Curve B
480 32 0.5 0.055 2
ts
kA
B
VV
V
C
D
E
⎡
⎣
⎢
⎤
⎦
⎥
=
⋅
×
<−
<
−
⎛
⎝
⎜
⎞
⎠
⎟
+