Presettable transducer for electrical quantities
A presentable voltage sensor includes an electrode faced by an electric field probe and connected to a voltage source; a screening conductive shell wrapping the probe and connected to a reference potential; a dielectric material housed within the shell and interposed between the probe and the electrode; a conditioning circuit connected to an exit of the sensor and having a resistor of resistance R m interposed between the probe and a second reference potential; and an integrator circuit formed from an RC network and having a resistor of resistance R i , a capacitor of capacitance C i , and a loss factor which, at a frequency of interest, is of an order of 10 −4 .
1. A presettable voltage sensor comprising:
a sensor connected to a voltage source to be measured, the sensor comprising,
an electrode electrically connected to the voltage source,
an electric field probe facing the electrode,
a screening conductive shell enclosing the probe and connected to a reference potential,
a dielectric material housed within the shell and interposed between said probe and the electrode; and
a conditioning circuit connected to an exit of the sensor and comprising a resistor of resistance R m interposed between the probe and a second reference potential, the conditioning circuit being configured to satisfy the following conditions:
R
m
<<
R
p
2
1
+
j
ω
C
2
R
p
2
R
m
>>
ω
L
pm
R
m
<<
1
j
ω
C
pm
R
m
<<
R
p
1
1
+
j
ω
C
1
R
p
1
in which:
C 1 indicates capacitance of a first capacitor having first plates formed by the electrode and the electric field probe, the first plates being immersed in the dielectric material,
C 2 indicates capacitance of a second capacitor having second plates formed by the electric field probe and the conductive shell, the dielectric, material surrounding the second plates,
R p1 indicates parasitic resistance of the first capacitor,
R p2 indicates parasitic resistance of the second capacitor,
L pm indicates parasitic inductance of the resistor of resistance R m , and
C pm indicates parasitic capacitance of the resistor of resistance R m ; and
an integrator circuit formed from an RC network, the integrator circuit being connected to the exit of the sensor and comprising a resistor of resistance R i , a capacitor of capacitance C i , and a loss factor which, at a frequency of interest, is of an order of 10 −4 , such to satisfy the following relationship:
arctan
(
-
ω
C
i
R
i
)
+
arctan
ω
R
p
1
2
R
m
C
1
R
m
R
p
1
+
R
m
2
+
ω
2
R
p
1
2
R
m
2
C
1
2
=
0
in which:
ω R i C i >>1.
2. The sensor of claim 1 , wherein the conditioning circuit also comprises an active amplification device for input signals of the integrator circuit.
3. The sensor of claim 2 , wherein the amplification for the input signals device is an operational amplifier.