GE 850 Instruction Manual page 367

CHAPTER 6: PROTECTION SETPOINTS
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
PICKUP VOLTAGE
Range: 0.00 to 1.50 x VT in steps 0.01
Default: 0.85 x VT
This setting specifies the phase undervoltage pickup level specified per times VT.
For example, a Pickup setting of 0.85 x VT with 13800:115 VT translates into 11.730kV (or
97.5V secondary).
If the Voltage Mode selection is Phase-phase and the Phase VT Connection (under
System/Voltage Sensing/Ph VT Bnk1-J2) selection is Wye, the previous example will
translate to the phase-phase voltage value of 11.730kV x 1.732 = 20.31kV
PICKUP VARS
Range: 1 to 65000 kvar in steps of 1
Default: 25 kvar
This setting specifies the pickup threshold for reactive power of the undervoltage/
reactive power function.
CURR SUPERV LEVEL
Range: 0.00 to 0.20 x CT in steps of 0.01
Default: 0.10 x CT
This setting sets the positive sequence current I1 pickup level.
This setting specifies the minimum positive sequence current level that inhibits this
element. If the positive sequence current is below this setting, the element is blocked.
As soon as the voltage falls below the Pickup Voltage and the positive sequence current
exceeds the Min Current and the reactive power falls below (when Var Direction =
Forward) or exceeds (when Var Direction = Reverse) the set value of Min Var, then the UV
Reactive Protection pickups.
VAR DIRECTION
Range: Forward, Reverse
Default: Forward
This setting specifies the flow direction of the watts(P) and Vars(Q), during normal and
fault situations, as seen from the grid or generator viewpoint.
When this value is programmed as Forward:
• During normal operation P > 0 and Q > 0; which means the generator delivers active
and inductive reactive power to the grid.
• During fault situation P > 0 and Q < 0; which means the generator delivers active
power to the grid and takes the inductive reactive power of the grid. Protection trips, if
the reactive power measurement value is negative (Q < 0).
When this value is programmed as Reverse:
• During normal operation P < 0 and Q < 0; which means the grid takes the active and
inductive reactive power of the generator.
• During a fault situation: P < 0 / P > 0 and Q > 0; which means the grid takes (or delivers)
the active power of (or to) the generator and the grid delivers inductive reactive power
to the generator. Protection trips, if the reactive power measurement value is positive
(Q > 0).
The figure: Flow direction of signed values for watts and VARs (see Metering/Power
section) illustrates the convention used for measuring power in the 8 Series devices.
PICKUP DELAY
Range: 0.000 to 600.000 s in steps of 0.001
Default: 0.500 s
This setting provides a definite time dropout delay for the trip function.
VOLTAGE ELEMENTS
6–99