Method and apparatus for testing the impedance of two electrically conducting members using two pairs of electrodes in which the spacing of the pairs is adjustable and the electrodes are independently axially slidable

• US 5,115,200 A
• Filed: 07/26/1990
• Issued: 05/19/1992
• Est. Priority Date: 10/22/1984
• Status: Expired due to Fees

• Current Assignee: Gould Electronics Incorporated (Eternal Materials Co., Ltd.)
• Original Assignee: Aerospatiale Societe Nationale Industrielle
• Inventors: Raymond, Michel J., Kayser, Jean-Paul, Lahitte, Pierre V. A.
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US07/559,498
• Time in Patent Office: 663 Days
• Field of Search: 324/691, 324/715, 324/718, 324/72.5, 324/158 P
• US Class Current: 324/718
• CPC Class Codes: G01N 27/20 Investigating the presence of flaws

Abstract

A process and apparatus are provided for checking the electric continuity of an electrically conducting material device, in which a current is injected between two points of said device and the resulting voltage between these points is measured. The invention is remarkable in that said current is an AC current and its pulsation is chosen sufficiently large so that the impedance between the two points, measured by the ratio of said voltage and of the current, may be considered as being equal to the product of the inductance of the path of the current between said points multiplied by said pulsation.

Claims

1. An apparatus for determining the quality of an elongate electrical junction between two electrically conducting members, wherein said apparatus comprises:

a) a generator for producing an alternating current having a frequency of 10KHz to 1MHz;

b) a voltmeter;

c) an ammeter operatively connected to said generator;

d) an impedance calculating means; and

e) a body having a first pair of spaced-apart parallel rectilinear electrodes extending from said body, said first pair of electrodes being operatively connected to said generator, a second pair of spaced-apart parallel electrodes extending from the body and closely-spaced to said first pair of electrodes, a first electrode of said first pair of electrodes and a first electrode of said second pair of electrodes being independently axially slidable within a first socket cooperating with said body, and a second electrode of said first pair of electrodes and a second electrode of said second pair of electrodes being independently axially slidable within a second socket socket cooperating with said body, at least one of said first and second socket being movable on said body for selectively adjusting the spacing between each electrode of said first and second pair of electrodes, each electrode further being independently biased by a complementary spring member to urge said electrode outwardly from said body, stop means for limiting outward displacement of each electrode, each of said spring members biasing said first pair of electrodes having a first end electrically connected to said electrode and a second end electrically connected to said generator, and wherein said spring members biasing said second pair of electrodes have a first end electrically connected to each electrode of said second pair of electrodes and a second end electrically connected to said volunteer, wherein said first pair of electrodes and spring members in cooperation with said generator, ammeter and electrically conducting members define a first electrical loop for injecting an alternating electric current across said electrical junction and wherein said second pair of electrodes and complementary spring members in cooperation with said voltmeter and said electrically conducting members define a second electrical loop substantially the same length at the first loop to measure the voltage drop across said junction;

wherein said impedance calculating means is operatively connected to said voltmeter and is operatively connected to said generator to calculate impedance across said junction.

2. The apparatus of claim 1 wherein said electrodes have a tip angled with respect to a longitudinal axis of said electrodes.

3. The apparatus of claim 1 including means to selectively adjust the spacing between each electrode of said first and second pair of electrodes.

4. The apparatus of claim 1 wherein each of said electrodes are electromagnetically shielded.

6. The apparatus of claim 1, wherein at least one of said first and second socket is movable on said body axially with respect to said electrodes for selectively adjusting the extension of the electrodes out of said body.

5. A method for determining electrical continuity and quality of a weld along an elongate welded junction between two electrically conducting members, comprising:

a) injecting an alternating electric current having a frequency between 10KHz and 1MHz between two points disposed on each side of said junction and measuring the AC voltage between said points with impedance measuring means comprising a body having a first pair of spaced-apart parallel rectilinear electrodes extending from said body, said first pair of electrodes being operatively connected to an alternating current generator, a second pair of spaced-apart parallel electrodes extending from the body and closely-spaced to said first pair of electrodes, a first electrode of said first pair of electrodes and a first electrode of said second pair of electrodes being independently axially slidable within a first socket cooperating with said body, and the other electrode of said first pair of electrodes and the other electrode of said second pair of electrodes being independently axially slidable within a second socket cooperating with said body, at least one of said first and second socket being movable on said body for selectively adjusting the spacing between each electrode of said first and second pair of electrodes, each electrode further being independently biased by a complementary spring member to urge said electrode outwardly from said body, stop means for limiting outward displacement of each electrode, each of said spring members biasing said first pair of electrodes having a first end electrically connected to said electrode and a second end electrically connected to a generator, each of said spring members biasing said second pair of electrodes having a first end electrically connected to each electrode of said second pair of electrodes and a second end electrically connected to a voltmeter, wherein said pair of electrodes and complementary spring members in cooperation with said generator and electrically conducting members define a first electrical loop for injecting said current, and wherein said second pair of electrodes and spring members in cooperation with said voltmeter and said electrically conducting members define a second electrical loop substantially the same length as the first loop for measuring a voltage across said junction;

b) measuring the voltage drop and calculating the impedance across said junction wherein said impedance is proportional to the electrical path between said points,

c) repeating steps a) and b) in at least two additional points disposed along each side of said junction to obtain at least two additional impedance measurements,

e) comparing the calculated impedance measurements thereby determining any discontinuity and the electric continuity along said junction.

7. A method for determining electrical continuity along an elongate junction between two electrically conducting members, with means comprising a body having a first pair of spaced-apart parallel rectilinear electrodes extending from said body, aid first pair of electrodes being operatively connected to a generator, a second pair of spaced-apart parallel electrodes extending from the body and closely-spaced to said first pair of electrodes, a first electrode of said first pair of electrodes and a first electrode of said second pair of electrodes supported by and being independently axially slidable within a first socket cooperating with said body, and a second electrode of said first pair of electrodes and a second electrode of said second pair of electrodes being independently axially slidable within a second socket cooperating with said body, at least one of said first and second socket being movable on said body for selectively adjusting the spacing between each electrode of said first and second pair of electrodes, each electrode further being independently biased by a complementary spring member to urge said electrode outwardly from said body, stop means for limiting outward displacement of each electrode, each of said spring members biasing said first pair of electrodes having a first end electrically connected to said electrode and a second end electrically connected to said generator, each of said spring members biasing said second pair of electrodes having a first end connected to each electrode of said second pair of electrodes and a second end electrically connected to a voltmeter, wherein said first pair of electrodes and complementary spring members in cooperation with said generator and electrically conducting members define a first electrical loop for injecting a current, and wherein said second pair of electrodes and spring members in cooperation with said voltmeter and said electrically conducting members define a second electrical loop substantially the same length as the first loop for measuring a voltage drop across said junction, said method comprising the steps of:

a) placing said means whereby said first electrodes of said first and second pair of electrodes contact a first point disposed on one side of said junction and said second electrodes of said first and second pair of electrodes contact a second point disposed on the other side of said junction;

b) injecting an alternating electric current having a frequency between 10KHz and 1MHz between said two points disposed on each side of said junction through said first pair of electrodes and measuring the AC voltage between said points through said second pair of electrodes;

c) measuring the voltage drop and calculating the impedance across said junction between said points;

d) repeating steps a), b) and c) in at least two additional points disposed along each side of said junction to obtain at least two additional impedance measurements;

e) comparing the calculated impedance measurements thereby determining any discontinuity and the electric continuity along said junction.

8. A method for determining electrical continuity along an elongate junction between two electrically conducting members, with means comprising a body having a first pair of spaced-apart parallel rectilinear electrodes extending from said body, said first pair of electrodes being operatively connected to a generator, a second pair of spaced-apart parallel electrodes extending from the body and closely-spaced to said first pair of electrodes, a first electrode of said first pair of electrodes and a first electrode of said second pair of electrodes being independently axially slidable within a first socket cooperating with said body, and a second electrode of said first pair of electrodes and a second electrode of said second pair of electrodes being independently axially slidable within a second socket cooperating with said body, said first socket being movable on said body for selectively adjusting the spacing between each electrode of said first and second pair of electrodes, and said second socket being movable on said body for selectively adjusting the extension of the corresponding electrodes of said first and second pair of electrodes out of said body, each electrode further being independently biased by a complementary spring member to urge said electrode outwardly from said body, stop means for limiting outward displacement of each electrode each of said spring members biasing said first pair of electrodes having a first end electrically connected to said electrode and a second end electrically connected to said generator, each of said spring members biasing said second pair of electrodes having a first end connected to each electrode of said second pair of electrodes and a second end electrically connected to a voltmeter, wherein said first pair of electrodes and complementary spring members in cooperation with said generator and electrically conducting members define a first electrical loop for injecting an alternating current, and wherein said second pair of electrodes and spring members in cooperation with said voltmeter and said electrically conducting members define a second electrical loop substantially the same length as the first loop for measuring a voltage drop across said junction, said method comprising the steps of:

a) placing said means whereby said first electrodes of said first and second pair of electrodes contact a first point disposed on one side of said junction and said second electrodes of said first and second pair of electrodes contact a point disposed on the other side of said junction;

b) injecting an alternating electric current having a frequency between 10KHz and 1MHz between said two points disposed on each side of said junction and measuring the AC voltage between said to points;

c) measuring the voltage drop and calculating the impedance across said junction;

d) repeating steps a), b) and c) in at least two additional points disposed along each side of said junction to obtain at least two additional impedance measurements;

e) comparing the calculated impedance measurements thereby determining any discontinuity and the electric continuity along said junction.