FUNCTION CHARACTERISTICS
47
NVA100X-D - Manual - 02 - 2016
Direct
Samples are processed by means DFT (Discrete Fourier Transform) algorithm and the phase and
amplitude of fundamental are computed:
Phase currents - side H and side L
I
L1H
,
I
L2H
,
I
L3H
,
I
L1L
,
I
L2L
,
I
L3L
Phase voltages
U
L1
,
U
L2
,
U
L3
Residual current
I
E1
and
I
E2
Residual voltage
U
E
Calculated
Frequency. The measure of period is taken preferably from phase voltage inputs
[1]
; when all volt-
age are missing the input current are employed.
Note 1 The frequency can also be measured on the three phase-to-phase voltages (calculated vectorially)
•
•
•
•
•
I L 1 . a i
(
I
nH
,
I
nL
)
i
L1H
,
i
L2H
,
i
L3H
i
L1L
,
i
L2L
,
i
L3L
DFT
≈
I
L1H
,
I
L2H
,
I
L3H
I
L1L
,
I
L2
L
,
I
L3
L
ACQUISITION
I L 1 . a i
(
I
nH
,
I
nL
)
i
L1H
,
i
L2H
,
i
L3H
i
L1L
,
i
L2L
,
i
L3L
DFT
≈
I
L1H
,
I
L2H
,
I
L3H
I
L1L
,
I
L2
L
,
I
L3
L
ACQUISITION
u
L1
,
u
L2
,
u
L3
DFT
U
L1
,
U
L2
,
U
L3
(
E
n
)
U L 1 . a i
VTs
≈
ACQUISITION
u
L1
,
u
L2
,
u
L3
DFT
U
L1
,
U
L2
,
U
L3
(
E
n
)
U L 1 . a i
VTs
≈
ACQUISITION
I E . a i
(
I
En1
,
I
En2
)
ACQUISITION
i
E1
,
i
E2
DFT
≈
I
E1
,
I
E2
I E . a i
(
I
En1
,
I
En2
)
ACQUISITION
i
E1
,
i
E2
DFT
≈
I
E1
,
I
E2
U E . a i
(
U
En
)
(
U
En
)
ACQUISITION
u
E
DFT (fundamental)
VT
≈
U
E
DFT (3rd harmonic)
U
E3H
U E . a i
(
U
En
)
(
U
En
)
ACQUISITION
u
E
DFT (fundamental)
VT
≈
U
E
DFT (3rd harmonic)
U
E3H
F. a i
(Hz)
(Hz)
u
L1
u
L2
U
L1
U
L2
ACQUISITION
≈
≈
u
L3
U
L3
I
L1H,
I
L1L
I
L2H,
I
L2L
I
L3H,
I
L3L
≈
u
L12
u
L23
u
L31
i
L1H,
i
L1L
i
L2H,
i
L2L
i
L3H,
i
L3L
≈
≈
≈
f
T
f
T
T
F. a i
(Hz)
(Hz)
u
L1
u
L2
U
L1
U
L2
ACQUISITION
≈
≈
u
L3
U
L3
I
L1H,
I
L1L
I
L2H,
I
L2L
I
L3H,
I
L3L
≈
u
L12
u
L23
u
L31
i
L1H,
i
L1L
i
L2H,
i
L2L
i
L3H,
i
L3L
≈
≈
≈
f
T
f
T