Thytronic NC20, Manual

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30
30 NC20 - Manual - 01 - 2015 FUNCTION CHARACTERISTICS
Direct
Frequency. The measure of period is taken preferably from voltage inputs; when all voltage are
missing the input current are employed.
Samples are processed by means DFT (Discrete Fourier Transform) algorithm and the phase and
amplitude of fundamental are computed:
Phase currents (RMS value of the fundamental and harmonic components) I
L1
, I
L2
, I
L3
Phase currents (RMS value) I
L1RMS
, I
L2RMS
, I
L3RMS
Phase voltages (RMS value of the fundamental component) U
L1
, U
L2
, U
L3
Unbalanced neutral current (RMS value of the fundamental component) I
N
•
•
•
•
•
F. a i
(Hz)
(Hz)
u
L1
u
L2
U
L1
U
L2
ACQUISITION
VT
≈
≈
u
L3
U
L3
I
L1
I
L2
CT
I
L3
≈
i
L1
i
L2
≈
≈
i
L3
≈
f
T
f
T T
F. a i
(Hz)
(Hz)
u
L1
u
L2
U
L1
U
L2
ACQUISITION
VT
≈
≈
u
L3
U
L3
I
L1
I
L2
CT
I
L3
≈
i
L1
i
L2
≈
≈
i
L3
≈
f
T
f
T
I L 1 . a i
( I
n
)
ACQUISITION
i
L1
, i
L2
, i
L3
DFT
CT
≈
DFT
DFT
I
L1
, I
L2
, I
L3
I
L1-2nd
, I
L2-2nd
, I
L3-2nd
I
L1-11th
, I
L2-11th
, I
L3-11th
I L 1 . a i
( I
n
)
ACQUISITION
i
L1
, i
L2
, i
L3
DFT
CT
≈
DFT
DFT
I
L1
, I
L2
, I
L3
I
L1-2nd
, I
L2-2nd
, I
L3-2nd
I
L1-11th
, I
L2-11th
, I
L3-11th
I L 1 R M S . a i
( I
n
)
I
L1RMS
I
L2RMS
I
L3RMS
I
L1
I
L1RMS
= √ ( I
L12
+ I
L1-2 nd2
+... I
L1-11t h2
)
I
L 2 RMS
= √ ( I
L 2 2
+ I
L 2 -2 nd2
+... I
L 2 -11t h2
)
I
L 3 RMS
= √ ( I
L 3 2
+ I
L 3 -2 nd2
+... I
L 3 -11t h2
)
I
L2
I
L3
I L 1 R M S . a i
( I
n
)
I
L1RMS
I
L2RMS
I
L3RMS
I
L1
I
L1RMS
= √ ( I
L12
+ I
L1-2 nd2
+... I
L1-11t h2
)
I
L 2 RMS
= √ ( I
L 2 2
+ I
L 2 -2 nd2
+... I
L 2 -11t h2
)
I
L 3 RMS
= √ ( I
L 3 2
+ I
L 3 -2 nd2
+... I
L 3 -11t h2
)
I
L2
I
L3
U L 1 . a i
ACQUISITION
u
L1
, u
L2
, u
L3
DFT
VT
≈ U
L1
, U
L2
, U
L3
( E
n
)
U L 1 . a i
ACQUISITION
u
L1
, u
L2
, u
L3
DFT
VT
≈ U
L1
, U
L2
, U
L3
( E
n
)
I N . a i
( I
Nn
)
ACQUISITION
i
N
DFT
CT
≈ I
N
I
N
I N . a i
( I
Nn
)
ACQUISITION
i
N
DFT
CT
≈ I
N
I
N