4.26
SEL-751A Relay
Instruction Manual
Date Code 20100129
Protection and Logic Functions
Basic Protection
Figure 4.17
IEC Short-Time Inverse Curve: C5
10
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50
60
70
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90
100
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.1
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.01
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Time in
Sec
onds
Tim
e in
Cy
cles
60 Hz
(50 Hz
)
6000 (5000)
3000 (2500)
1500 (1250)
600 (500)
300 (250)
150 (125)
60 (50)
30 (25)
15 (12.5)
6 (5)
3 (2.5)
Multiples of Pickup
0.05
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Summary of Contents for 751A
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