William M Swain

US Patent:

6940267, Sep 6, 2005

Filed:

Dec 27, 1995

Appl. No.:

08/579395

Inventors:

William H. Swain - Sarasota FL, US

International Classification:

G01R001/20
G01R033/00
H01F007/06

US Classification:

324127, 296021, 324117 H, 324117 R, 702191

Abstract:

The accuracy of certain sensors is greatly improved by improving their signal to noise ratio (SNR) in the presence of an interfering noise. Sensors were discovered which have a SNR which substantially changes when an operating parameter is selectively modulated to different magnitudes. Some noise can be practically eliminated. In the simplest form, the sensor is operated where it is both stable and close to its best SNR This is usually faster and less costly, but the noise is never completely eliminated. Often, the method involves operating the sensor in first one state and then another wherein the operating parameter has conditions where the sensor is stable, reproducible, and reliable, and wherein the SNRs are substantially different. The output of a state is combined with the output of another state in such a way that the noise cancels but a signal remains. Often the output in a state having greater noise is attenuated until it matches the noise content of another state having less noise.

US Patent:

20050057242, Mar 17, 2005

Filed:

Oct 1, 2004

Appl. No.:

10/955507

Inventors:

William Swain - Sarasota FL, US

International Classification:

H04B007/10

US Classification:

324127000

Abstract:

The accuracy of certain sensors is improved by improving their signal to noise ratio (SNR) in the presence of an interfering noise. Sensors were discovered which have a SNR which substantially changes when an operating parameter is selectively modulated to different magnitudes. In the simplest form, the sensor is operated where it is both stable and close to its best SNR. This is usually faster and less costly, but the noise is never completely eliminated. This invention has first been applied to Swain Meter type clamp-on DC ammeters. Some results are good—the benefit in SNR is between 2 and 4. Swain Meter is a registered Trademark of the William H. Swain Co.

US Patent:

6278952, Aug 21, 2001

Filed:

Dec 8, 1998

Appl. No.:

9/206960

Inventors:

William H Swain - Sarasota FL

International Classification:

G01R 19145

US Classification:

702 64

Abstract:

A machine, called Reliability gage, for evaluating a non-contact ammeter. Reliability gage outputs at least one of estimated merit reliability, and fault location, and fault assessment of best use of a gaged ammeter. A Reliability gage includes at least one merit measure which has an output indicative of the quality of at least one parameter of the gaged ammeter. A Reliability gage also has at least one reference merit magnitude representative of a "clean" ammeter, that is to say, first rate, or alternatively, a faulted short, faulted gap, etc. , and a comparitor with processor and output so that evaluation of the gaged ammeter is done systematically to provide the required output. Reliability gage is applicable to both AC and DC Swain Meter type non-contact ammeters. Some reliability gages are adapted for use by a human operator who may make use of spreadsheets.

US Patent:

63236354, Nov 27, 2001

Filed:

Oct 18, 1999

Appl. No.:

9/419941

Inventors:

William H. Swain - Sarasota FL

International Classification:

G01R 120
G01R 3300
G01R 3304
H01F 3012
H01F 3828

US Classification:

324127

Abstract:

A Swain type direct current clamp-on sensor called MER2 is disclosed with improved magnetic error reduction from undesired magnetic fields generated by noise sources for accurate measurement of low currents. The sensor is comprised of a split core with non uniform magnetic structure designed to concentrate the magnetomotive force generated by the current being measured, and also by the switching magnetomotive force, through the windings near the lips of the sensor for better signal to noise ratio. The sensor core has non-uniform windings with greater ampere-turns near the lips than in other sectors of core remote from the lips so that the flux density of magnetic material in and near the lips is better switched. Furthermore, there is a provision for combining and adjusting current signals such that the noise is largely canceled. A method of making the direct current clamp-on MER2 is also disclosed.