GE 745 Instruction Manual page 220

A2 METERING
6.3.3 Frequency
 FREQUENCY
6.3.4 Tap Changer
 TAP CHANGER
6.3.5 Voltage
 VOLTAGE
6–12
The harmonic derating factor for each of the windings shows the effect of non-sinusoidal
load currents on power transformer's rated full load current. The calculations are based on
ANSI/IEEE standard C57.110-1986. The actual values messages display the harmonic
derating factor for windings 1 through 3.
PATH: ACTUAL VALUES
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MESSAGE
The SYSTEM FREQUENCY is calculated from the voltage input provided that voltage
sensing is enabled and the injected voltage is above 50% of VT. If these criteria are not
satisfied, then it is determined from winding 1 phase A current provided that it is above
0.05 × CT. If frequency still cannot be calculated, "0.00 Hz" is displayed, though the
sampling rate is then set for the
setpoint. The FREQUENCY DECAY RATE
FREQUENCY
frequency can be calculated.
PATH: ACTUAL VALUES A2 METERING
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This message displays the actual tap position. If tap position sensing is disabled, "n/a" will
be displayed.
PATH: ACTUAL VALUES
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MESSAGE
MESSAGE
For phase-to-neutral input voltages, the
to-line equivalent.
A2 METERING FREQUENCY

SYSTEM FREQUENCY:
0.00 Hz
FREQUENCY DECAY
RATE: 0.00 Hz/s
S2 SYSTEM SETUP TRANSFORMER

can only be calculated if system
TAP CHANGER

TAP CHANGER
POSITION: n/a
A2 METERING VOLTAGE

SYSTEM LINE-TO-LINE
VOLTAGE: 0.00 kV
VOLTS-PER-HERTZ:
0.00 V/Hz
LINE-NTRL VOLTAGE:
0.00 kV at 0° Lag
SYSTEM LINE-TO-LINE VOLTAGE
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 6: ACTUAL VALUES
NOMINAL

displays its line-