Electricity: measuring and testing – Conductor identification or location – Inaccessible
Patent
1985-10-22
1987-10-06
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Conductor identification or location
Inaccessible
219110, 2191171, G01R 2716, B23K 1124
Patent
active
046985840
ABSTRACT:
An ohmmeter for measuring very low electric resistances, for example the very low resistance of a very high current electric joint, which ohmmeter comprises a source for establishing a measuring current through the joint to thereby create a voltage drop proportional to the magnitude of the measuring current and to the resistance to be measured. A first integrator integrates a signal respresentative of the magnitude of the measuring current in order to produce a first integration signal, while a second integrator integrates the voltage drop proportional to the measuring current and to the very low resistance in order to produce a second integration signal. The two integrators are simultaneously reset to zero so that they both start their respective integrations at a same instant. The first integration signal is compared to a reference signal through a comparator. When the amplitude of the first integration signal reaches the amplitude of the reference signal, the comparator delivers a signal which stops the integration carried out by the second integrator. The second integration signal is then stored, this signal having an amplitude constituting a measure of the very low electric resistance. A display device receives the stored integration signal for displaying the value of the measured resistance.
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patent: 4104578 (1978-01-01), Thuot
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Electrical Times, Nov. 16, 1972, R. L. Jackson: "Measuring Contact Resistance Accurately in the Field".
Metal Progress, Mar. 1985, AT&T "It's Steel. But Which Steel?"
Materials Evaluation, Aug. 1983, R. L. Cohen and K. W. West, "Characterization of Metals and Alloys by Electrical Resistivity Measurements", pp. 1074 to 1077.
Funkschau, No. 8, Avril 1981, p. 98, Munich DE; G. Osswald: "Widerstands-Messung mit DVM".
Eisenzopf Reinhard J.
Harvey Jack B.
Hydro - Quebec
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