GE Multilin F60 Feeder Protection System 6-23
6 ACTUAL VALUES 6.3 METERING
6
N = 64 is the number of samples per cycle
ω
0
= 2πf is the angular frequency based on the system frequency (50 or 60 Hz)
k = 1, 2,..., N – 1 is the index over one cycle for the Fast Fourier Transform (FFT)
m is the last sample number for the sliding window
h = 1, 2,..., 25 is the harmonic number
The short-time Fourier transform is applied to the unfiltered signal:
(EQ 6.3)
The harmonics are a percentage of the fundamental signal obtained as a ratio of harmonic amplitude to fundamental ampli-
tude multiplied by 100%. The total harmonic distortion (THD) is the ratio of the total harmonic content to the fundamental:
(EQ 6.4)
Voltage harmonics are not available on F60 relays configured with the high-impedance fault detection (Hi-Z) fea-
ture.
Voltage harmonics are calculated only for Wye connected phase VTs. Ensure the SYSTEM SETUP AC INPUTS
VOLTAGE BANK F5 PHASE VT XX CONNECTION setting is “Wye” to enable voltage harmonics metering.
6.3.3 SENSITIVE DIRECTIONAL POWER
PATH: ACTUAL VALUES METERING SENSITIVE DIRECTIONAL POWER
The effective operating quantities of the sensitive directional power elements are displayed here. The display may be useful
to calibrate the feature by compensating the angular errors of the CTs and VTs with the use of the RCA and CALIBRATION
settings.
6.3.4 SYNCHROCHECK
PATH: ACTUAL VALUES METERING SYNCHROCHECK SYNCHROCHECK 1(4)
If a synchrocheck function setting is "Disabled", the corresponding actual values menu item is not displayed.
SENSITIVE
DIRECTIONAL POWER
DIRECTIONAL POWER 1
3Φ: 0.000 W
MESSAGE
DIRECTIONAL POWER 2
3Φ: 0.000 W
SYNCHROCHECK 1
SYNCHROCHECK 1 DELTA
VOLT: 0.000 V
MESSAGE
SYNCHROCHECK 1 DELTA
PHASE: 0.0°
MESSAGE
SYNCHROCHECK 1 DELTA
FREQ: 0.00 Hz
F
real
mh,()
2
N
----
fm k–() h ω
0
tk()⋅⋅()cos⋅()
k
=
F
imag
mh,()
2
N
----
fm k–()h ω
0
tk()⋅⋅()sin⋅()
k
=
F
ampl
mh,() F
real
mh,()
2
F
imag
mh,()
2
+=
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