GE C70 Instruction Manual page 412
Capacitor bank protection and control system ur series
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- Instruction manual (702 pages) ,
- Communications manual (532 pages) ,
- Communications manual (526 pages)
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6.3 METERING
h) CURRENT HARMONICS AND THD METERING
PATH: ACTUAL VALUES
CURRENT HARMONICS
SRC 1
The metered current harmonics values are displayed in this menu. The "SRC 1" text will be replaced by whatever name
was programmed by the user for the associated source (see
harmonics are measured for each source for the total harmonic distortion (THD) and 2nd to 25th harmonics per phase.
i) VOLTAGE HARMONICS AND THD METERING
PATH: ACTUAL VALUES
VOLTAGE HARMONICS
SRC 1
6
The metered voltage harmonics values are displayed in this menu. The "SRC 1" text will be replaced by the programmed
name for the associated source (see the
To extract the 2nd to 25th voltage harmonics, each harmonic is computed on a per-phase basis, where:
N = 64 is the number of samples per cycle
ω
= 2πf is the angular frequency based on the system frequency (50 or 60 Hz)
0
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:
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:
6-18
METERING
SOURCE SRC 1
SRC 1
Ib:
0.0 Ic:
SRC 1
MESSAGE
Ib:
0.0 Ic:
SRC 1
MESSAGE
Ib:
0.0 Ic:
SRC 1
25TH Ia:
MESSAGE
Ib:
0.0 Ic:
METERING
SOURCE SRC 1
SRC 1
Vb:
0.0 Vc:
SRC 1
MESSAGE
Vb:
0.0 Vc:
SRC 1
MESSAGE
Vb:
0.0 Vc:
SRC 1
25TH Va:
MESSAGE
Vb:
0.0 Vc:
SETTINGS
2
F
(
m h
,
)
--- -
=
real
N
k
2
F
(
m h ,
)
--- -
=
imag
N
k
(
m h ,
)
F
F
=
ampl
THD
=
C70 Capacitor Bank Protection and Control System
CURRENT HARMONICS
THD Ia:
0.0
0.0%
2ND Ia:
0.0
0.0%
3RD Ia:
0.0
0.0%
↓
0.0
0.0%
SETTINGS
SYSTEM SETUP
VOLTAGE HARMONICS
THD Va:
0.0
0.0%
2ND Va:
0.0
0.0%
3RD Va:
0.0
0.0%
↓
0.0
0.0%
SYSTEM SETUP
SIGNAL SOURCES
(
f m k
(
)
⋅
cos
(
h ω
⋅
⋅
t k ( )
)
)
–
0
(
f m k
(
)
⋅
sin
(
h ω
⋅
⋅
t k ( )
)
)
–
0
2
2
(
,
)
(
,
)
m h
F
m h
+
real
imag
2
2
2
F
F
...
F
+
+
+
2
3
25
6 ACTUAL VALUES
). Current
SIGNAL SOURCES
menu).
(EQ 6.3)
(EQ 6.4)
GE Multilin
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