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3.3
Date Code 20060320
Instruction Manual
SEL-311C Relay
Distance, Out-of-Step, Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Distance Elements
Figure 3.1
Positive-Sequence Polarized Mho Element With Reach Equal to Line Impedance
I • X
I • R
Vmem
Z • I
V
Restrain
cos (
θ
) < 0
Test Angle
cos (
θ
) > 0?
Test Angle
cos (
θ
) > 0?
Test Angle
cos (
θ
) > 0?
Operate
cos (
θ
) > 0
(Z • I–V)
I • Z
source
Balance
cos (90˚) = 0
I • X
I • R
Vmem
Z • I
V
(Z • I–V)
I • Z
source
I • X
I • R
Vmem
Z • I
V
(Z • I - V)
I • Z
source
Forward External Fault
Forward Fault at the Balance Point
Forward Internal Fault
Summary of Contents for SEL-311C
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