Patent US3676774A successfully refreshed from Google Patents.
US3676774A
Expired / Lapsed
US
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Potentiometric resistance measuring system
Assignee: FKI Industries Inc
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Filing: 1970-05-05
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Granted: 1972-07-11
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Expires: 1990-05-05
Abstract
Abstract A system for measuring the resistance of a current-carrying inductive element comprises a pair of coupled, self-balancing potentiometers and an adjustable voltage delay circuit. One of the potentiometers is adapted for measuring the element voltage (after it is subjected to a predetermined time delay) by comparing it with a constant reference voltage. The other potentiometer is adapted for measuring the element resistance by comparing this measured element voltage with a voltage corresponding to the current through the element. The time delay introduced in the voltage measurement is chosen to delay voltage transients by a time equal to the inductive time lag of the element current, so that the resistance measurement is not significantly affected by such transients.
Inventors
- 👤 Joseph F Stokes
- 👤 George E Van Vessem
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:36
CPC Classifications
G; G01; G01K; G01K7/00; G01K7/16; G01K7/18; G01K7/20; G01K7/206
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
127 words
A system for measuring the resistance of an inductive current-carrying element comprising: a voltage delay circuit for producing a voltage to be measured, which voltage to be measured is proportional to the voltage drop across said element and wherein voltage changes are delayed with respect to changes in said voltage drop across said element by a time substantially equal to the inductive time lag of the element current; a first voltage measuring instrument of the potentiometer type for measuring the voltage produced by said voltage delay circuit; shunt means for producing a voltage proportional to the current flowing through said element; and a second voltage measuring instrument of the potentiometer type for comparing the voltage measured by said first instrument with the voltage produced by said shunt.
Claim 2
Independent Claim
127 words
A system for measuring the resistance of an inductive current-carrying element comprising: a voltage delay circuit for producing a voltage to be measured, which voltage to be measured is proportional to the voltage drop across said element and wherein voltage changes are delayed with respect to changes in said voltage drop across said element by a time substantially equal to the inductive time lag of the element current; a first voltage measuring instrument of the potentiometer type for measuring the voltage produced by said voltage delay circuit; shunt means for producing a voltage proportional to the current flowing through said element; and a second voltage measuring instrument of the potentiometer type for comparing the voltage measured by said first instrument with the voltage produced by said shunt.
Claim 3
Dependent Claim
42 words
A system according to claim 1 wherein said system includes a voltage divider network for reducing the proportion of the element voltage applied to said first instrument and which has a total resistance which is large compared to that of the element.
Claim 4
Dependent Claim
21 words
A system according to claim 2 wherein said first and second voltage measuring instruments of the potentiometer type are self-balancing potentiometers.
Claim 5
Dependent Claim
46 words
A system according to claim 3 wherein the balancing apparatus of the first self-balancing potentiometer is coupled to an adjustable reference voltage source in the second self-balancing potentiometer for adjusting said reference voltage to a value proportional to the element voltage measured by the first potentiometer.
Claim 6
Dependent Claim
23 words
A system according to claim 4 wherein said first and second self-balancing potentiometers each comprise a resistive bridge around a reference voltage source.
Claim 7
Dependent Claim
57 words
A system according to claim 5 wherein the reference voltage source of said first self-balancing potentiometer is a constant voltage source and the adjustable reference voltage source of said second potentiometer comprises a resistive bridge which is unbalanced by the balancing arrangement of said first self-balancing potentiometer to produce a voltage proportional to the measured element voltage.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-11 | 1976-01-10 | 1976-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-11 | 1980-01-10 | 1980-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-11 | 1984-01-10 | 1984-07-11 | $7700.00 | Window Closed / Lapsed |