Capacitor Control - GE C70 Instruction Manual
Capacitor bank protection and control system
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- Instruction manual (708 pages) ,
- Communications manual (532 pages) ,
- Instruction manual (672 pages)
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CHAPTER 6: ACTUAL VALUES
6.3.2.9 Voltage harmonics and THD metering
ACTUAL VALUES METERING SOURCE SRC 1 VOLTAGE HARMONICS
VOLTAGE HARMONICS
SRC 1
This menu displays metered voltage harmonics values. The "SRC 1" text is replaced by the programmed name for the
associated source (see the
SETTINGS SYSTEM SETUP SIGNAL SOURCES
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
amplitude multiplied by 100%. The total harmonic distortion (THD) is the ratio of the total harmonic content to the
fundamental:
Voltage harmonics are calculated only for Wye connected phase VTs. Ensure that the
INPUTS VOLTAGE BANK F5 PHASE VT XX CONNECTION
NOTE
metering.
6.3.3 Capacitor control
ACTUAL VALUES METERING CAPACITOR CONTROL
CAPACITOR CONTROL
These values indicate the time remaining before the next permissible close operation for each of the four capacitor banks.
C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL
SRC 1 THD Va: 0.0
Vb: 0.0 Vc: 0.0%
SRC 1 2ND Va: 0.0
Vb: 0.0 Vc: 0.0%
SRC 1 3RD Va: 0.0
Vb: 0.0 Vc: 0.0%
SRC 1 25TH Va: 0.0
Vb: 0.0 Vc: 0.0%
2
F
(
m h ,
)
=
-- -
(
f m k
(
)
⋅
cos
–
real
N
k
2
F
(
m h ,
)
=
-- -
(
f m k
(
)
⋅
–
imag
N
k
2
F
(
m h ,
)
=
F
(
m h ,
)
+
ampl
real
2
2
THD
=
F
+
F
+
... F
2
3
CAP 1 DISCHARGE TIME:
0 s
CAP 4 DISCHARGE TIME:
0 s
menu).
(
h ω
⋅
⋅
t k ( )
)
)
0
sin
(
h ω
⋅
⋅
t k ( )
)
)
0
2
F
(
m h ,
)
imag
2
+
25
setting is "Wye" to enable voltage harmonics
METERING
Eq. 6-3
Eq. 6-4
SYSTEM SETUP AC
6-17
6
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