GE D90 Plus Instruction Manual page 149

CHAPTER 7: PROTECTION
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
This menu allows the user to specify the parameters for each voltage input. The
and
Ratio Auxiliary VT Ratio
matching primary voltage in a synchrocheck application. The
settings are used to derive secondary voltage values from the per-
Auxiliary VT Nominal
unit settings used in protection elements. Protection functions that require phase-to-
neutral or zero-sequence quantities will not function correctly for delta VT configurations.
The following voltage input settings are available.
Phase VT Connection
Range: Wye, Delta
Default: Wye
This setting specifies the phase VT connection type for the corresponding voltage input.
An open-delta source VT connection would be entered as "Delta".
Phase VT Ratio
Range: 1.00 to 2400.00 in steps of 0.001
Default: 1.00
This setting specifies the phase VT ratio for the corresponding voltage input. It is
typically used for calculation of primary metering values or matching primary voltage in
a synchrocheck application.
Phase VT Nominal
Range: 50 to 240 volts in steps of 1
Default: 120 volts
This setting specifies the nominal phase VT voltage for the corresponding voltage input.
It is typically used to derive secondary voltage values from the per-unit settings used in
protection elements.
The typical
Phase VT Nominal
appearing at the relay input terminals when nominal voltage is applied to the VT
primary. For example, on a system with a 13.8 kV nominal primary voltage and with a
14400:120 V VT in a delta connection, the secondary voltage is (13800 V / 14400) × 120 =
115 V. Thus, the Phase VT Nominal
Auxiliary VT Connection
Range: Vag, Vbg, Vcg, Vab, Vbc, Vca, Vn
Default: Vag
This setting specifies the auxiliary VT connection type for the corresponding voltage
input.
Auxiliary VT Ratio
Range: 1.00 to 2400.00 in steps of 0.001
Default:
This setting specifies the auxiliary VT ratio for the corresponding voltage input. It is
typically used for calculation of primary metering values or matching primary voltage in
a synchrocheck application.
Auxiliary VT Nominal
Range: 50 to 240 volts in steps of 1
Default: 120 volts
This setting specifies the nominal auxiliary VT voltage for the corresponding voltage
input. It is typically used to derive secondary voltage values from the per-unit settings
used in protection elements.
settings are used for calculation of primary metering values or
setting is the phase-to-phase secondary voltage
setting would be 115 volts.
POWER SYSTEM
Phase VT
and
Phase VT Nominal
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