Schweitzer Engineering Laboratories SEL-311C - Figure 3.1 Positive-Sequence Polarized Mho Element with Reach Equal to Line Impedance

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