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4.2. IEC60255-151 Curves
The SIA-B relay complies with the curves shown in standard IEC 60255-151:
•
Inverse Curve
•
Very Inverse Curve
•
Extremely Inverse Curve
•
Long time Inverse Curve
There is a general mathematical equation that defines the time in seconds as a function of the
current:
K
D
B
Q
V
D
A
t
P
+
+
−
=
adjusted
I
I
V
=
Parameters
A
P
Q
B
K
Long time Inverse
120
1
1
0
0
Ext. Inverse
80
2
1
0
0
Very Inverse
13,5
1
1
0
0
Inverse
0,14
0,02
1
0
0
The curve can move from its axis using the D time selection device, which the user can adjust.
I
adjusted
is the initial operating current, set by the user.
4.3. IEEE Curves
The IEEE curves follow the following mathematical equation:
( )
+
−
=
B
V
A
TD
t
P
1
adjusted
I
I
V
=
And we have the following curves:
•
Inverse Curve
•
Very Inverse Curve
•
Extremely Inverse Curve
