CHAPTER 6: SETPOINTS S3 PROTECTION
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 6–45
Phase directional (67P)
The Phase Directional element (one for each of phases A, B and C) is used to discriminate
between faults that occur in the forward direction, and faults that occur in the reverse
direction. The Phase Directional element can be used either individually for control or
alarm by energizing the auxiliary output relays, or as a part of the Phase Time, or
Instantaneous, over-current elements to define the tripping direction. (See the setup for
Phase TOC and Phase IOC elements.)
The polarizing signal for the Phase Directional element is determined by comparing the
phase angle between the current from the phase CTs and the line-line voltage from the
VTs, and the set MTA angle.
The following table shows the operating and polarizing signals used for phase directional
control:
When line voltage is below the minimum polarizing voltage threshold (MIN POL VOLTAGE),
the direction is undefined. In this case, phase overcurrent protection elements are blocked
if “BLK OC DIR UN” setting is enabled and directional is not disabled.
Figure 6-19: Phase A polarization
The following path is available using the keypad. For instructions on how to use the
keypad, please refer to Chapter 3 - Working with the Keypad.
PATH: SETPOINTS > S3 PROTECTION > SETPOINT GROUP 1(2) > PHASE DIR
PHASE OPERATING SIGNAL POLARIZING SIGNAL Vpol
ABC PHASE SEQUENCE ACB PHASE SEQUENCE
A Angle of Ia Angle of Vbc × (Angle of MTA) Angle of Vcb × (Angle of MTA)
B Angle of Ib Angle of Vca × (Angle of MTA) Angle of Vac × (Angle of MTA)
C Angle of Ic Angle of Vab × (Angle of MTA) Angle of Vba × (Angle of MTA)
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