ABB Distribution Protection Unit 1500R
1-10
Protective Functions
9/99
website:www.abb.com/papd
Table 1-12. Constants for IEC Time Overcurrent Characteristics
Curve
Extremely Inverse
Very Inverse
Inverse
Long Time Inverse
K
80.0
13.5
0.14
120.0
α
2.0
1.0
0.02
1.0
Timing Curves
Time Overcurrent Curve Equation
IEC
Time multiple range 0.05 to 1.0 in steps of 0.05
Trip Time =
Reset Time = instantaneous
= multiples of pickup current
x time multiple
G
G
b
G
b
K
G
α
– 1