Calibration of a device for measuring an electric field in a conducting medium

Patent metadata

Field	Value
Publication number	US-9933471-B2
Application number	US-201415033990-A
Country	US
Kind code	B2
Filing date	Nov 4, 2014
Priority date	Nov 7, 2013
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

A device for measuring an electric field in a conducting medium comprises: two electrodes separated by a volume of an insulating medium; a device for measuring current coupled to said electrodes; and adjustment elements making it possible to vary a quantity on which the electrical conductivity of the field measuring device depends.

First claim

The invention claimed is:

1. A device for measuring an electric field in a conducting medium, comprising:
two electrodes separated by a volume of an insulating medium;
a current measurement device coupled to said electrodes; and
adjustment elements enabling the adjustment of a variable having the electric conductivity (σ c ) of the field measurement device depending thereon, said variable being comprised in the group comprising the impedance (Z int ) between the two electrodes of the field measurement device, the distance (L) between the two electrodes, and an active surface (SA) of at least one of said electrodes.

2. The device of claim 1 , wherein said variable is the impedance between the two electrodes of the field measurement device.

3. The device of claim 2 , wherein said adjustment elements comprise a variable resistor coupled to said electrodes.

4. The device of claim 1 , wherein said variable is the distance (L) between the two electrodes.

5. The device of claim 4 , wherein said adjustment elements comprise at least one arm of adjustable length coupled to said electrodes.

6. The device of claim 1 , wherein said variable is an active surface area of at least one of said electrodes.

7. The device of claim 6 , wherein at least one of said electrodes comprises a plurality of conductive panels capable of being interconnected via switches.

8. The device of claim 6 , wherein said adjustment elements comprise an insulating element capable of sliding in front of at least one of said electrodes, causing a variation of the electrode surface area in contact with the conducting medium.

9. The device of claim 1 , further comprising control and processing elements capable of:
a) measuring the current (I) flowing between the two electrodes for at least two different values of said variable; and
b) deducing from the measurements the amplitude of the electric field (E) of the conducting medium, and at least one variable from among the impedance of said electrodes and the conductivity of the conducting medium.

10. The device of claim 9 , wherein said control and processing elements are capable, at step a), of measuring the current (I) flowing between the two electrodes for at least three different values of said variable and, at step b), deducing from said measurements the amplitude of the electric field (E) of the conducting medium, the impedance of said electrodes, and the conductivity (σ e ) of the conducting medium.

11. The device of claim 9 , wherein step b) comprises solving a system of equations of the following type:

I
E

=

f
⁡

(

L

S
A

*

(

Z
elec

+

Z
int

)

*

σ
e

)

,

where I designates the current measured between the electrodes, L designates the distance between electrodes, SA designates the active surface area of the electrodes, Z elec designate the impedance of the electrodes, Z int designates the impedance between electrodes, σ e designates the conductivity of the conducting medium, and f designates an analytic function representative of the variation of conversion coefficient I/E according to ratio σ c /σ e , with σ c =L/(S A *(Z elec +Z int ).

12. A method of calibrating the field measurement device of claim 1 , comprising the steps of:
a) measuring the current (I) flowing between the two electrodes for at least two different values of said variable; and
b) deducing from said measurements the amplitude of the electric field (E) of the conducting medium, and at least one variable from among the impedance of said electrodes and the conductivity (σ e ) of the conducting medium.

13. The method of claim 12 , wherein at step a), the current (I) flowing between the two electrodes is measured for at least three different values of said variable and, at step b), the amplitude of the electric field (E) in the conducting medium, the impedance of said electrodes, and the conductivity (σ e ) of the conducting medium are deduced from said measurements.

Assignees

• Commissariat Energie Atomique
• Inst Polytechnique Grenoble

Inventors

• Baicry Mathieu
• Le Prado Matthieu
• Lefrou Christine
• Rouve Laure-Line

Classifications

• G01R29/0814

  Field measurements related to measuring influence on or from apparatus, components or humans (EMC, EMI and similar testing in general G01R31/001), e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning · CPC title

• G01R5/28

  Electrostatic instruments · CPC title

• G01R35/00

  Testing or calibrating of apparatus covered by the other groups of this subclass · CPC title

• G01R31/2642

  Testing semiconductor operation lifetime or reliability, e.g. by accelerated life tests · CPC title

• G01R29/12 Primary

  Measuring electrostatic fields {or voltage-potential} · CPC title