Permeameter having a differential transformer probe with a reduced distance between the detecting coils
US5103173A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Mar 4, 1991 |
| Grant date | Apr 7, 1992 |
| Priority date | — |
| Expiry date | Mar 4, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/1223
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Permeameter suited for measuring permeability of a small, non-magnetic (i.e., the permeability value is close to 1) object. The probe of the permeameter is of the differential transformer type with an exciting coil and two detecting coils placed at both ends of the exciting coil. The difference in the outputs of the detecting coils is analyzed and the effect of the eddy current is effectively eliminated, whereby the signal representing the permeability of the object is extracted from the difference signal by the phase shift analysis. By reducing the distance between the two detecting coils, the influence of the disturbance of the eddy current at the boundary of the object sample is minimized and the permeameter can measure a small object sample without sacrificing accuracy and sensitivity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.