Patent US3879657A successfully refreshed from Google Patents.
US3879657A
Expired / Lapsed
US
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Electrical apparatus for minimizing polarization of conductivity cell electrodes
Assignee: Ecolab Inc
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Filing: 1973-12-21
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Granted: 1975-04-22
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Expires: 1993-12-21
Abstract
Abstract Electrical apparatus for reducing the drift in the set point of an electrical bridge type conductivity sensor utilizing a pulse producing circuit (e.g. an astable multivibrator type switching device) to provide an AC voltage of very short duration to the conductivity cell electrodes for minimizing the cumulative polarization thereof. Pulse lengthening circuitry is also provided to assure that the relatively short output pulses from the bridge circuit are of sufficient duration to properly operate apparatus for injecting an additive product into the conductive medium.
Inventors
- 👤 Marcus I Nystuen
- 👤 Roger A Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:07
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/22; G01N; G01N27/00; G01N27/02; G01N27/04
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
153 words
Apparatus for measuring the conductivity of a conductive medium, and for minimizing errors due to polarization, comprising: a. means for supplying AC electrical power having a frequency of approximately 60 hertz; b. switching means connected to said AC supply for periodically switching on and off the alternating current, said switching means operatively establishing a ratio of off to on time for said alternating current being switched on for less than one second during any one period; c. means for sensing the conductivity of a medium, including a single conductivity cell having a pair of electrodes operable when energized to develop an output signal indicative of the conductivity of the medium; and d. means for connecting the output of the switching means to said single conductivity cell whereby AC power of about 60 hertz is intermittently applied according to the switching schedule established by said switching means to the conductivity cell for energization thereof.
Claim 2
Dependent Claim
153 words
Apparatus for measuring the conductivity of a conductive medium, and for minimizing errors due to polarization, comprising: a. means for supplying AC electrical power having a frequency of approximately 60 hertz; b. switching means connected to said AC supply for periodically switching on and off the alternating current, said switching means operatively establishing a ratio of off to on time for said alternating current being switched on for less than one second during any one period; c. means for sensing the conductivity of a medium, including a single conductivity cell having a pair of electrodes operable when energized to develop an output signal indicative of the conductivity of the medium; and d. means for connecting the output of the switching means to said single conductivity cell whereby AC power of about 60 hertz is intermittently applied according to the switching schedule established by said switching means to the conductivity cell for energization thereof.
Claim 3
Dependent Claim
153 words
Apparatus for measuring the conductivity of a conductive medium, and for minimizing errors due to polarization, comprising: a. means for supplying AC electrical power having a frequency of approximately 60 hertz; b. switching means connected to said AC supply for periodically switching on and off the alternating current, said switching means operatively establishing a ratio of off to on time for said alternating current being switched on for less than one second during any one period; c. means for sensing the conductivity of a medium, including a single conductivity cell having a pair of electrodes operable when energized to develop an output signal indicative of the conductivity of the medium; and d. means for connecting the output of the switching means to said single conductivity cell whereby AC power of about 60 hertz is intermittently applied according to the switching schedule established by said switching means to the conductivity cell for energization thereof.
Claim 4
Dependent Claim
153 words
Apparatus for measuring the conductivity of a conductive medium, and for minimizing errors due to polarization, comprising: a. means for supplying AC electrical power having a frequency of approximately 60 hertz; b. switching means connected to said AC supply for periodically switching on and off the alternating current, said switching means operatively establishing a ratio of off to on time for said alternating current being switched on for less than one second during any one period; c. means for sensing the conductivity of a medium, including a single conductivity cell having a pair of electrodes operable when energized to develop an output signal indicative of the conductivity of the medium; and d. means for connecting the output of the switching means to said single conductivity cell whereby AC power of about 60 hertz is intermittently applied according to the switching schedule established by said switching means to the conductivity cell for energization thereof.
Claim 5
Dependent Claim
34 words
Apparatus according to claim 1 wherein the switching means is adapted to switch the AC current on for a period of about 1/10 to 1/30 of a second, once every 8 to 12 seconds.
Claim 6
Dependent Claim
130 words
Apparatus for measuring the conductivity of an acqueous electrolyte solution, and for minimizing errors due to electrode polarization, comprising: a. means for supplying AC electrical power having a frequency of approximately 60 hertz; b. means for sensing the conductivity of an aqueous electrolyte solution, including a single conductivity cell having a pair of electrodes operable when energized to develop an output signal indicative of the conductivity of said solution; and c. electronic switching means operatively connected to said AC supply means and to said conductivity cell for periodically supplying AC current to said Single conductivity cell for energization thereof, said switching means having an on time for energizing said conductivity cell of less than one second, and an off time of at least five times longer than said on time.
Claim 7
Dependent Claim
130 words
Apparatus for measuring the conductivity of an acqueous electrolyte solution, and for minimizing errors due to electrode polarization, comprising: a. means for supplying AC electrical power having a frequency of approximately 60 hertz; b. means for sensing the conductivity of an aqueous electrolyte solution, including a single conductivity cell having a pair of electrodes operable when energized to develop an output signal indicative of the conductivity of said solution; and c. electronic switching means operatively connected to said AC supply means and to said conductivity cell for periodically supplying AC current to said Single conductivity cell for energization thereof, said switching means having an on time for energizing said conductivity cell of less than one second, and an off time of at least five times longer than said on time.
Claim 8
Dependent Claim
27 words
Apparatus according to claim 3 wherein said switching means is adapted to provide an on time of approximately 2 to 6 cycles of the power supply frequency.
Claim 9
Dependent Claim
26 words
Apparatus according to claim 4 wherein said switching means is adapted to provide an off time of approxmately 8 to 12 seconds between successive on times.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |