Thytronic NA30

FUNCTION CHARACTERISTICS
31
NA30 - Manual - 04 - 2022
• Direct
• Calculated
• Phase
• Sequence
• Harmonic
• Demand
Direct
• Frequency. The measure of period is taken on the input phase currents.
Samples are processed by means DFT (Discrete Fourier Transform) algorithm and the phase and
amplitude of fundamental are computed:
• Phase currents I
L1
, I
L2
, I
L3
• Residual current I
E
• Residual voltage U
E
Calculated
By means vector addition of direct measures the following are calculated (RMS value of fundamen-
tal components):
• Thermal image ∆θ
F.ai
(Hz)
ACQUISITION
I
L1
I
L2
CT
I
L3
i
L1
i
L2
≈
≈
i
L3
≈
f
T
IL1.ai
(I
n
)
ACQUISITION
i
L1
, i
L2
, i
L3
DFT
CT
≈
I
L1
, I
L2
, I
L3
IE.ai
(I
En
)
ACQUISITION
i
E
DFT
CT
≈
I
E
UE.ai
(U
En
)
(U
En
)
ACQUISITION
u
E
DFT (fundamental)
VT
≈
U
E
DFT (3rd harmonic)
U
E3H
Theta.ai
I
L1
I
2
I
2
= (I
L1
+ e
-j120°
I
L2
+ e
+j120°
I
L3
)
I
1
= (I
L1
+ e
+j120°
I
L2
+ e
-j120°
I
L3
)
I
L3
I
L2
I
1
I
th
= √(I
1
2
+ K
2
2
∙I
2
2
)
∆θ
(∆θ
B
)
2
d∆θ
dt
I
B
I
th
∆θ
T+ T+
( )
+ =