GE D90 Plus Instruction Manual page 148

POWER SYSTEM
NOTE:
Voltage inputs
140
Phase CT Nominal
Range: 0.00 to 30.00 amps in steps of 0.01
Default: 5.00 amps
This setting specifies the nominal phase CT current for the corresponding current input.
It is used to derive secondary current values from per-unit settings used in protection
elements.
Auxiliary CT Ratio
Range: 1 to 65000 in steps of 1
Default: 1
This setting specifies the auxiliary CT ratio for the corresponding current input. It is used
for calculation of primary metering values and for ratio matching when multiple CT
inputs are added within a source. This setting is not available if the
"3-Phase".
Auxiliary CT Nominal
Range: 0.00 to 30.00 amps in steps of 0.01
Default: 5.00 amps
This setting specifies the nominal auxiliary CT current for the corresponding current
input. It is used to derive secondary current values from per-unit settings used in
protection elements. This setting is not available if the
Current Cutoff Level
Range: 0.002 to 0.020 pu in steps of 0.001
Default: 0.020 pu
This setting modifies the current cut-off threshold. Very low currents (1 to 2% of the
rated value) are very susceptible to noise. Some customers prefer very low currents to
display as zero, while others prefer the current be displayed even when the value reflects
noise rather than the actual signal. The D90
and angles of the measured currents. If the magnitude is below the cut-off level, it is
substituted with zero. This applies to phase and ground current phasors as well as true
RMS values and symmetrical components. The cut-off operation applies to quantities
used for metering, protection, and control, as well as those used by communications
protocols. Raw current samples available via oscillography are not subject to cut-off.
Lower the
Current Cutoff Level
valid measurements. Unless dictated otherwise by a specific application, the default
setting of "0.020 pu" is recommended.
Select the Settings > Protection > Power System > AC Inputs - Voltage menu item to
open the voltage input configuration window.
Figure 106: Voltage input configuration settings
Plus
applies a cut-off value to the magnitudes
setting with care as the D90
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: PROTECTION
setting is
Connection
setting is "3-Phase".
Connection
Plus
accepts lower signals as