FANOX SIL-D00, User Manual, Page: 58 / 226

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If overcurrent fault is 11xI
n
=1100 Ap, IEC inverse curve defines a tripping value of 0.1425s
(Figure1) for 50/51 function. It is considered that this time is too high, so when current fault
reaches 11xI
n
, definite time overcurrent function will be work.
The figure below (Figure 2), shows the tripping curve of the relay:
Figure 2. Relay tripping curve
APPLICATION EXAMPLE 2:
Starting from the following information:
Line details:
•
Transformation ratio of CT =500/1
•
Primary current: I
p
=500 A
50/51 function settings
•
Curve type: IEEE Extremely Inverse
•
Dial: 2.20
•
Tap: 1xI
n
50 function settings
•
Tap: 14xI
n
•
Time delay: 0.1 s