Entec EVRC2A-N6-NT - Page 177

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ENHANCED TECHNOLOGY
7.13.3. SEF Directional Controls (67SEF)
The SEF direction control process a very similar method to the ground directional controls.
7.13.4. Negative Sequence Directional Controls (67(46))
The negative sequence voltage V
2
provides the direction of negative sequence pole in the power
system. The negative sequence direction control is determined as comparing the negative
sequence voltage(V
2
) to the direction of the negative sequence current(I
2
). The Maximum Torque
Angle is set between ∠0 to ∠359 degree. The factory default value for maximum torque angle
has a lead of ∠135 degree over V
2.
If the polarized voltage drops below minimum polarized voltage, the negative sequence direction
control will lose direction and will not trip. Then any fault on the distribution line may trip due to
the negative sequence overcurrent element which is non-directional.
The negative sequence direction control can be programmed for non-direction or to provide a trip
for current flow in the forward or reverse direction only.
The following diagram shows the phasor diagram for I
2
directional polarization in the complex
plane.