Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Frequency of cyclic current or voltage
Patent
1975-01-21
1976-02-03
Corcoran, Robert J.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Frequency of cyclic current or voltage
73362R, G01R 3312
Patent
active
039367347
ABSTRACT:
A method for contactless measurement of conductivity and/or temperature on metals by means of the eddy current effect induced within the metal by an alternating magnetic field produced by an excitation coil fed with alternating current arranged with its axis perpendicular to the surface of the metallic test specimen, there being in addition to the excitation coil a pair of measuring coils of equal radius arranged coaxially and symmetrically with respect to the excitation coil at each end respectively of the excitation coil and having an axial length substantially less than that of the excitation coil. The two measuring coils are connected electrically in series opposition and the phase angle between the current in the measuring coils and the current in the excitation coil is taken as an indication of the measured variable. In order to reduce the so-called "lift-off" effect to a minimum and allow accurate contactless measurement such that substantial tolerances are permissible for the distance between the test specimen and measuring head which carries the coils, the radius between the excitation coil on the one hand, and the measuring coils on the other, is smaller than 1/4 or greater than 4, depending on whether the measuring coils are located respectively outside or inside the excitation coil, and the measuring head is at such a distance from the specimen surface that the phase angle between the excitation-coil signal and the measuring-coil signal exhibits a maximum.
REFERENCES:
patent: 2764734 (1956-09-01), Yates
Dodd, C.V.; A Portable Phase-Sensitive E.C. Instrument; Mat. Eval. Mar. 1968; pp. 33-36.
Dodd et al., Thickness Measurements Using E.C. Techniques; Mat. Eval. May 1973; pp. 73-84.
Dodd, C.V.; Applications of a Phase-Sensitive E.C. Instrument; Mat. Eval; June, 1964; pp. 260-262 & 272.
Brandli Gerold
Keller Pierre
BBC Brown Boveri & Company Limited
Corcoran Robert J.
LandOfFree
Method for contactless measurement of conductivity and/or temper does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for contactless measurement of conductivity and/or temper, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for contactless measurement of conductivity and/or temper will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2124301