GE F650 Instruction Manual page 218

5 SETTINGS
These elements can also be set as inverse time curves. This family of curves is defined by the following formula:
Where:
T = operation time
D = operation time setting (delay)
V = voltage applied to the relay
Vpickup = pickup setting (Pickup level)
5.4.8.1 PHASE UNDERVOLTAGE ELEMENT (27P)
This element may be used to give a desired time-delayed operating characteristic versus the applied fundamental voltage
(phase-to-ground or phase-to-phase for wye VT connection, or phase-to phase- for Delta VT connection) or as a Definite
time element. The element resets instantaneously if the applied voltage exceeds the dropout voltage.
The delay setting selects the minimum operating time of the phase undervoltage. The minimum voltage setting selects the
operating voltage below which the element is blocked (a setting of "0" will allow a dead source to be considered a fault
condition.
This element generates independent pickup and trip signals per phase, and general pickup and trip signals for the element.
These last signals can be selected, by means of the operation logic setting, to be an OR (any phase signal) or an AND (all
phase signals).
GEK-106310AB
1
Figure 5–15: INVERSE TIME UNDERVOLTAGE CURVES
F650 Digital Bay Controller
5.4 PROTECTION ELEMENTS
5
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