12.3.1.1
Standard inverse-time characteristics for overvoltage protection
The trip times for the standard overvoltage IDMT curves are defined with the coefficients
A, B, C, D and E.
The inverse trip time can be calculated with the formula:
t s
k A
B
V
V
V
C
D
E
=
⋅
×
−
>
>
−
+
GUID-6E9DC0FE-7457-4317-9480-8CCC6D63AB35-ANSI V1 EN
(Equation 39)
t [s] trip time in seconds
V
measured voltage
V> the set value of
Pickup value
k
the set value of
Time multiplier
Table 441:
Curve coefficients for the standard overvoltage IDMT curves
Curve name
A
B
C
D
E
(17) Inverse Curve A
1
1
0
0
1
(18) Inverse Curve B
480
32
0.5
0.035
2
(19) Inverse Curve C
480
32
0.5
0.035
3
Section 12
1MRS240050-IB C
General function block features
608
REF615R
Technical Manual
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