Sel 751A - Figure 4.11 U.S. Extremely Inverse Curve: U4

4.20
SEL-751A Relay Instruction Manual Date Code 20100129
Protection and Logic Functions
Basic Protection
Figure 4.11 U.S. Extremely Inverse Curve: U4
3.00
2.00
1.00
0.50
15.00
12.00
10.00
8.00
6.00
5.00
4.00
.01
.5 .6 .7 .8 .9 1
.02
.03
.04
.05
.09
.07
.06
.08
.1
.2
.3
.4
.5
.7
.6
.9
.8
1
423 56789
10
40
20
30
70
50
60
80
90
100
80
10
2
3
6
4
5
7
9
8
20
50
30
40
60
70
100
90
Time in Seconds
Multiples of Pickup
Time in Cycles 60 Hz (50Hz)
3 (2.5)
6 (5)
15 (12.5)
30 (25)
60 (50)
600 (500)
150 (125)
300 (250)
1500 (1250)
3000 (2500)
6000 (5000)