266 D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
GROUPED PROTECTION ELEMENTS CHAPTER 7: PROTECTION
V is the secondary voltage applied to the relay
V
pickup
is the pickup level
Figure 227: Inverse time undervoltage curves
NOTE:
At 0% of pickup, the operating time is equivalent to the undervoltage delay setting.
Phase undervoltage
The phase undervoltage element can be used to give a required time delay operating
characteristic versus the applied fundamental voltage (phase-to-ground or phase-to-
phase for wye VT connections, or phase-to-phase for delta VT connections) or as a definite
time element. The element resets instantaneously if the applied voltage exceeds the
dropout voltage.
Select the Settings > Protection > Elements > Group 1 > Voltage > Phase UV menu to
open the phase undervoltage configuration window.
Figure 228: Phase undervoltage configuration settings
The following settings are available for each phase undervoltage element.
Function
Range: Enabled, Disabled
Default: Disabled
This setting enables and disables the phase undervoltage protection element.
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