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3-84
Protection Functions
857-UM001A-EN-P – July 2009
Example for Delay type "Moderately inverse (MI)":
k
=
0.50
I
=
4 pu
I
=
pickup
A
=
0.0515
B
=
0.114
C
=
0.02
⎡
⎢
⎢
. 0
0515
=
⋅
t
. 0
50
⎢
. 0
02
⎛
⎞
4
⎢
⎜
⎟
⎢
⎝
⎠
⎣
2
The operation time in this example will be 1.9 seconds. The same result
can be read from Figure 3.47.
Figure 3.44 – ANSI/IEEE Long Time
Inverse Delay
2 pu
⎤
⎥
⎥
+
=
. 0
1140
1
9 .
⎥
−
⎥
1
⎥
⎦
Figure 3.45 – ANSI/IEEE Long Time
Very Inverse Delay
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