Sel SEL-421 - Page 124

R.1.82
SEL-421 Relay Reference Manual Date Code 20111215
Protection Functions
Inverse-Time Overcurrent Elements
Figure 1.56 IEC Long-Time Inverse—C4
0.20
0.10
0.05
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.30
.7.6.5
.1
.9.8 1
.4
.2
.3
.5
.6
.8
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.9
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2
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5
7
6
423 765
10
98
40
20
30
70
50
60
80
90
100
50
9
8
10
20
30
40
300
200
100
80
60
70
90
1000
900
800
700
600
500
400
Time in Seconds
Multiples of Pickup
Time in Cycles 60 Hz (50 Hz)
30 (25)
60 (50)
150 (125)
300 (250)
3000 (2500)
600 (500)
1500 (1250)
6000 (5000)
15000 (12500)
30000 (25000)
60000 (50000)