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5.2.
IEEE Curves
The SIL-A relay complies with the curves shown in standard IEEE:
•
Inverse Curve
•
Very Inverse Curve
•
Extremely Inverse Curve
There is a general mathematical equation that defines the time in seconds as a function of the
current:
( )
+
−
=
B
V
A
TD
t
P
1
adjusted
I
I
V
=
Which relate to the parameters figuring in the following table:
Parameters
A
P
B
Ext. Inverse
28,2
2
0,1217
Very Inverse
19,61
2
0,491
Inverse
0,0515
0,02
0,114
The curve can move from its axis using the TD time selection device, which the user can adjust.
I
adjusted
is the initial operating current, set by the user.