Sel SEL-421 - Page 120

R.1.78
SEL-421 Relay Reference Manual Date Code 20111215
Protection Functions
Inverse-Time Overcurrent Elements
Figure 1.52 U.S. Short-Time Inverse—U5
0.50
1.00
2.00
6.00
3.00
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5.00
10.00
8.00
12.00
15.00
.01
.5 .6 .7 .8 1.9
.02
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.7
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9
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90
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9
2
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Time in Seconds
Multiples of Pickup
Time in Cycles 60 Hz (50 Hz)
3 (2.5)
6 (5)
15 (12.5)
60 (50)
30 (25)
150 (125)
300 (250)
1500 (1250)
600 (500)
3000 (2500)
6000 (5000)