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Patent US4437065A successfully refreshed from Google Patents.
US4437065A
Expired / Lapsed
US
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Arrangement for monitoring cathodically protected structures
Assignee: NV NEDERLANDSE GASUNIE GROINGEN NETHERLANDS LAAN CARPUS DEN HOORN 102
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Filing: 1981-09-01
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Granted: 1984-03-13
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Expires: 2001-09-01
Abstract
Abstract An arrangement for monitoring the potential of a cathodically protected buried metallic structure. The apparatus includes a measuring electrode to be inserted into the soil and electrically coupled to the metallic structure to be measured, a reference electrode placed on or in the soil, and a measuring circuit for measuring the potential difference between the measuring and reference electrodes. The measuring circuit also generates a reference potential to generate a pulse signal having a frequency proportional to the amount by which the measured potential exceeds the reference potential. A counter counts the number of pulses during a measuring cycle that is measured by a timer. A computer computes from timer and counter output data, the average value of the amount by which the measured potential exceeds the reference potential during a measuring cycle.
Inventors
- 👤 Gerrit Woudstra
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:18
CPC Classifications
G; G01; G01N; G01N17/00; G01N17/02; C; C23; C23F; C23F13/00; C23F13/02; C23F13/04
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
250 words
An apparatus for monitoring the potential with respect to the soil of a metallic structure buried in soil and cathodically protected by an externally applied DC voltage, comprising: a measuring electrode for placement in the soil adjacent to the structure to be monitored, the electrode being electrically connected to the structure; a reference electrode placed on or in the soil; a measuring circuit coupled to the measuring and reference electrodes for measuring the potential difference between the measuring and reference electrodes, the measuring circuit including a generator for generating a reference potential; a comparator for comparing the measured potential difference between the measuring electrode and the reference electrode with the reference potential and providing a comparison signal indicative of the amount by which the measured potential difference exceeds the reference potential; a pulse signal generator, for generating, in response to the comparison signal, a pulse stream signal having a pulse frequency proportional to the comparison signal and therefore proportional to the amount by which the measured potential difference exceeds the reference potential; a counter for counting the number of pulses of the pulse stream signal during a measuring time cycle; timer means for determining and recording the time interval of the measuring time cycle; and means, coupled to the counter and timer means so as to receive data therefrom, for computing, after completion of the measuring cycle, the average value of the amount by which the measured potential has been higher than the reference potential during the measuring time cycle.
Claim 2
Independent Claim
250 words
An apparatus for monitoring the potential with respect to the soil of a metallic structure buried in soil and cathodically protected by an externally applied DC voltage, comprising: a measuring electrode for placement in the soil adjacent to the structure to be monitored, the electrode being electrically connected to the structure; a reference electrode placed on or in the soil; a measuring circuit coupled to the measuring and reference electrodes for measuring the potential difference between the measuring and reference electrodes, the measuring circuit including a generator for generating a reference potential; a comparator for comparing the measured potential difference between the measuring electrode and the reference electrode with the reference potential and providing a comparison signal indicative of the amount by which the measured potential difference exceeds the reference potential; a pulse signal generator, for generating, in response to the comparison signal, a pulse stream signal having a pulse frequency proportional to the comparison signal and therefore proportional to the amount by which the measured potential difference exceeds the reference potential; a counter for counting the number of pulses of the pulse stream signal during a measuring time cycle; timer means for determining and recording the time interval of the measuring time cycle; and means, coupled to the counter and timer means so as to receive data therefrom, for computing, after completion of the measuring cycle, the average value of the amount by which the measured potential has been higher than the reference potential during the measuring time cycle.
Claim 3
Dependent Claim
21 words
An apparatus according to claim 1, wherein the time interval of the measuring cycle is between 1 day and 1 year.
Claim 4
Dependent Claim
16 words
An apparatus according to claim 1 or 2, wherein the timer means comprises a digital clock.
Claim 5
Independent Claim
188 words
An apparatus for monitoring the potential with respect to the soil of a metallic structure situated in the soil and cathodically protected by an externally applied DC voltage, comprising: a measuring electrode for placement in the soil adjacent to the structure to be monitored, the electrode being electrically connected to the structure; a reference electrode placed on or in the soil; a measuring circuit coupled to the measuring and reference electrodes for measuring the potential difference between the measuring and reference electrodes, the measuring circuit including a reference stage for generating a fixed but adjustable reference potential, a comparison stage for continuously generating, during a measuring cycle, a difference signal indicative of the amount by which the measured potential difference is higher than the reference potential generated by the reference stage, a voltage to frequency converter for generating a pulse stream signal, the frequency of which is proportional to the difference signal, a pulse counter for counting a number of pulses provided by the voltage to frequency converter during the measuring cycle, and means for recording the time interval between the start and end of the measuring cycle.
Claim 6
Independent Claim
188 words
An apparatus for monitoring the potential with respect to the soil of a metallic structure situated in the soil and cathodically protected by an externally applied DC voltage, comprising: a measuring electrode for placement in the soil adjacent to the structure to be monitored, the electrode being electrically connected to the structure; a reference electrode placed on or in the soil; a measuring circuit coupled to the measuring and reference electrodes for measuring the potential difference between the measuring and reference electrodes, the measuring circuit including a reference stage for generating a fixed but adjustable reference potential, a comparison stage for continuously generating, during a measuring cycle, a difference signal indicative of the amount by which the measured potential difference is higher than the reference potential generated by the reference stage, a voltage to frequency converter for generating a pulse stream signal, the frequency of which is proportional to the difference signal, a pulse counter for counting a number of pulses provided by the voltage to frequency converter during the measuring cycle, and means for recording the time interval between the start and end of the measuring cycle.
Claim 7
Dependent Claim
53 words
An apparatus according to claim 4, wherein the measuring circuit comprises a computer stage for determining the average value of the amount by which the measured potential has been higher than the reference potential during the measuring cycle from the number of pulses counted in the pulse counter and the recorded time interval.
Claim 8
Dependent Claim
20 words
An apparatus according to claim 5, wherein the pulse counter and the computer stage are constructed as a single unit.
Claim 9
Dependent Claim
22 words
An apparatus according to claim 4 or 5 or 6, wherein the means for recording a time interval comprises a digital clock.
Claim 10
Dependent Claim
40 words
An apparatus according to claim 4 or 5 or 6, further comprising a digital display for displaying any of (a) the number of pulses counted during a measuring cycle, (b) the recorded time interval and (c) the calculated average value.
Claim 11
Dependent Claim
36 words
An apparatus according to claim 7, further comprising a digital display for displaying any of (a) the number of pulses counted during a measuring cycle, (b) the recorded time interval and (c) the calculated average value.
Claim 12
Dependent Claim
148 words
An apparatus according to claim 4 or 5 or 6, wherein the reference stage of the measuring circuit comprises a DC voltage source, an adjustable potentiometer circuit and a first operational amplifier connected as voltage-follower, and wherein the comparison stage of the measuring circuit comprises a solid-stage selector and a second, a third and a fourth operational amplifier, the second operational amplifier being combined with the selector to form a discriminator circuit at the output of which either the set comparison potential or the potential of the measuring electrode appears, the potential appearing being the higher of the two potentials, the third and fourth operational amplifiers being combined to form a difference circuit to which the comparison potential and the output potential of the discriminator circuit are fed, and at the output of which a voltage difference appears which is proportional to the difference of these two potentials.
Claim 13
Dependent Claim
145 words
An apparatus according to claim 7, wherein the reference stage of the measuring circuit comprises a DC voltage source, an adjustable potentiometer circuit and a first operational amplifier connected as voltage-follower, and wherein the comparison stage of the measuring circuit comprises a solid-stage selector and a second, a third and a fourth operational amplifier, the second operational amplifier being combined with the selector to form a discriminator circuit at the output of which either the set comparison potential or the potential of the measuring electrode appears, the potential appearing being the higher of the two potentials, and the third and fourth operational amplifiers being combined to form a difference circuit to which the comparison potential and the output potential of the discriminator circuit are fed, and at the output of which a voltage difference appears which is proportional to the difference of these two potentials.
Claim 14
Dependent Claim
145 words
An apparatus according to claim 8, wherein the reference stage of the measuring circuit comprises a DC voltage source, an adjustable potentiometer circuit and a first operational amplifier connected as voltage-follower, and wherein the comparison stage of the measuring circuit comprises a solid-stage selector and a second, a third and a fourth operational amplifier, the second operational amplifier being combined with the selector to form a discriminator circuit at the output of which either the set comparison potential or the potential of the measuring electrode appears, the potential appearing being the higher of the two potentials, and the third and fourth operational amplifiers being combined to form a difference circuit to which the comparison potential and the output potential of the discriminator circuit are fed, and at the output of which a voltage difference appears which is proportional to the difference of these two potentials.
Claim 15
Independent Claim
189 words
A method for the long term monitoring of the potential with respect to the soil of a metallic structure situated in the soil and cathodically protected by an externally applied DC voltage, comprising the steps of: inserting a measuring electrode into the soil adjacent to the structure to be monitored; placing a reference electrode in the soil; electrically connecting the measuring electrode to the structure; generating a reference potential; measuring the potential difference between the measuring and reference electrodes; comparing the measured potential difference with the reference potential and generating a comparison signal indicative of the amount by which the measured potential exceeds the reference potential; generating a pulse signal having a pulse frequency proportional to the magnitude of the comparison signal so that the frequency is proportional to the amount by which the measured potential exceeds the reference potential; counting the number of pulses of the pulse signal during a measuring cycle; determining and recording a time interval of the measuring cycle; and computing, after completing the measuring cycle, the average value of the amount by which the measured potential exceeds the reference potential during the measuring cycle.
Claim 16
Independent Claim
189 words
A method for the long term monitoring of the potential with respect to the soil of a metallic structure situated in the soil and cathodically protected by an externally applied DC voltage, comprising the steps of: inserting a measuring electrode into the soil adjacent to the structure to be monitored; placing a reference electrode in the soil; electrically connecting the measuring electrode to the structure; generating a reference potential; measuring the potential difference between the measuring and reference electrodes; comparing the measured potential difference with the reference potential and generating a comparison signal indicative of the amount by which the measured potential exceeds the reference potential; generating a pulse signal having a pulse frequency proportional to the magnitude of the comparison signal so that the frequency is proportional to the amount by which the measured potential exceeds the reference potential; counting the number of pulses of the pulse signal during a measuring cycle; determining and recording a time interval of the measuring cycle; and computing, after completing the measuring cycle, the average value of the amount by which the measured potential exceeds the reference potential during the measuring cycle.
Claim 17
Dependent Claim
21 words
A method according to claim 13 wherein the time interval of the measuring cycle is between 1 day and 1 year.
References Cited (Backward Citations)
US2700501A
Cited
US4258323A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-13 | 1987-09-12 | 1988-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-13 | 1991-09-12 | 1992-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-13 | 1995-09-12 | 1996-03-13 | $7700.00 | Window Closed / Lapsed |