isolated current voltage transducers

Other Types of Voltage Transducers Technologies
6.2.3 Typical applications
Presently, the main market for the AV 100 is in traction
inverters, but they can also be used in or adapted for any
industrial application.
• Auxiliary and main converters (input voltage, DC link,
output phase voltages).
• Chopper and power factor correction circuits.
• Battery chargers.
• Sub-Stations and others.
6.2.4 Calculations & Properties
Calculation of the measuring resistor RM
The AV 100 family provides a current output. This current
can be transformed into a voltage with the addition of a
measuring resistor, R M
, at the output which cannot exceed a
defined R Mmax
value, based on the available voltage at the
transducer supply and the maximum voltage measured. For
the AV 100 family, R Mmax
can be easily calculated using the
following formula:
R Mmax
= ((V Cmin
- 5.1) • V PN
/ (V Pmax
• I SN
) - 31) • 0.9 [Ω]
With:
V Cmin
= Minimum value of the secondary power supply [V]
5.1 = Internal voltage drop of the electronics [V]
V PN
= Nominal measurable primary voltage [V]
V Pmax
= Maximum measurable primary voltage [V]
I SN
= Secondary output current at V PN
[A]
31 = Secondary internal resistance [Ω]
0.9 = Safety factor [-]
The R Mmax
values indicated in the datasheets are the values
calculated using V Pmax
.
+HT
-HT
Negative unipolar power supply
In this case, the zener diode must be inserted as shown in
Figure 51 and the zener voltage, V Z
, must be greater than
5.1 volts. The maximum measuring resistance becomes:
R Mmax
= [(abs(V Cmin
) - 2.0 - V Z
) • V PN
/ (V Pmax
• I SN
) - 31] • 0.9
with abs (V Cmin
) corresponding to the absolute value of the
V Cmin
voltage.
+HT
-HT
+HT
-HT
+HT
-HT
+
M
-
Figure 50: Electric connection – AV 100 with positive unipolar
power supply
+
M
Figure 51: Electric connection – AV 100 with negative unipolar
power supply
-
R M
R M
+Vc
0V
0V
-Vc
Unipolar Power Supply
For unipolar voltage measurements the AV 100 family can
operate from a unipolar secondary supply. A positive supply
allows positive voltage measurements while a negative
supply allows negative voltage measurements.
Positive unipolar power supply
In this case, a zener diode must be inserted as shown in
Figure 50 and the zener voltage, V Z
, must be greater than
2.0 V. The maximum measuring resistance becomes:
R M max
= [(V Cmin
- 5.1 - V Z
) • V PN
/ (V Pmax
• I SN
) - 31] • 0.9
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