ABB RELION 620 Series Technical Manual page 872

Section 12
General function block features
12.3.1.1
866
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:
k A ⋅
 
t s
=
   
− >
V V
 
B × − C
 
V >
 
GUID-6E9DC0FE-7457-4317-9480-8CCC6D63AB35-ANSI V1 EN
t [s] trip time in seconds
V measured voltage
Pickup value
V> the set value of
Time multiplier
k the set value of
Table 615: Curve coefficients for the standard overvoltage IDMT curves
Curve name A
(17) Inverse Curve A 1
(18) Inverse Curve B 480
(19) Inverse Curve C 480
+ D
E
B C
1
32
32
1MAC504801-IB E
D
0 0
0.5 0.035
0.5 0.035
(Equation 112)
E
1
2
3
620 series ANSI
Technical Manual