Synchronous detection and remote monitoring and regulating of cell potential for cathodic protection

• US 6,625,570 B2
• Filed: 06/18/2001
• Issued: 09/23/2003
• Est. Priority Date: 06/20/2000
• Status: Expired due to Fees

• Current Assignee: James B. Sullivan, Joseph J. Pierro Jr, Timothy B. Mullins
• Original Assignee: James B. Sullivan, Joseph J. Pierro Jr, Timothy B. Mullins
• Inventors: Sullivan, James B., Mullins, Timothy B., Pierro, Joseph J. Jr.
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Walling, Meagan S.
• Application Number:
  US09/883,794
• Publication Number:
  US 20020008042A1
• Time in Patent Office: 827 Days
• Field of Search: 702/188, 702/89, 702/106, 361/18, 327/551
• US Class Current: 702/188
• CPC Class Codes: G01N 17/02 Electrochemical measuring systems for weathering, corrosion or corrosion-protection measurement

Abstract

A system and method for regulating an adjustable DC supply and continuously and remotely monitoring measurements of reference cell potential and/or current for cathodic protection of a structure is disclosed. Cathodic protection devices use a logic circuit and/or microprocessor based monitor for removing identifiable components and noise from the system to arrive at the DC bias. A method is implemented herein to arrive at the true value of a reference cell potential measurement determined within a sample collection point or window calculated for the reference cell signal while the impressed current is still being applied. This measurement can be compared to a calculated shutdown and is communicated to a central computer accessible via a network such as the Internet. All output is automatically regulated and checked for target window accuracy using an automated voting scheme.

Claims

1. A method for regulating output and continuously and remotely monitoring measurements of reference cell potential or current for cathodic protection of a structure, comprising:

providing one or more cathodic protection devices located proximate to said structure to vary said output;

piggybacking an internal interface unit accessible by a central computer on each of said cathodic protection devices;

communicating with each of said cathodic protection devices by means of said internal interface unit;

providing and displaying said measurements to said central computer;

comparing and cross-checking said measurements using a voting scheme, thereby improving confidence in said measurements;

varying said output being applied to said structure as determined by said voting scheme such that said measurements fall within a target window; and

removing distorting effects, residual components, and noise from said measurements to arrive at an amplitude for a DC bias, wherein said amplitude for said DC bias is correlated to said reference cell potential.

2. The method of claim 1, wherein said output is an adjustable DC supply for regulating said reference cell potential.

3. The method of claim 1, wherein said output is an adjustable DC supply for regulating said current.

4. The method of claim 1, wherein said measurements are provided and displayed using the Internet.

5. The method of claim 1, wherein said measurements are provided and displayed using a cellular phone.

6. The method of claim 1, wherein said measurements are provided and displayed using said central computer.

7. The method of claim 1, wherein said measurements are provided and displayed using a radio.

8. A system for regulating output and continuously and remotely monitoring measurements of reference cell potential or current for cathodic protection of a structure, comprising:

one or more cathodic protection devices adapted to function in reference cell mode or current mode and located proximate to said structure to vary said output;

an internal interface unit accessible by a central computer and piggybacked on each of said cathodic protection devices;

a central station running said central computer and communicating with each of said cathodic protection devices by means of said internal interface unit;

a voltage detection means working in conjunction with said cathodic protection device providing and displaying said measurements to said central computer, wherein said voltage detection means comprises a low pass filtered output voltage of a current sense device;

a voting scheme means for comparing and cross-checking said measurements, thereby improving confidence in said measurements; and

,

a regulation means for varying said output as determined by said voting scheme.

9. The system of claim 8, wherein said current sense device is a hall effect device.

10. The system of claim 8, wherein said current sense device is a shunt.

11. The system of claim 8, wherein said current sense device is a current sense resistor placed in series with power flow.

12. The system of claim 8, wherein said regulation means comprises an adjustable DC supply controllable by a shutdown controller under logic sequence control.

13. The system of claim 12, wherein said adjustable DC supply comprises course upper and lower limits that define an adjustment window, and further comprises fine taps set within said adjustment window.

14. The system of claim 8, wherein said regulation means comprises a transformer tap controller connected by a series of switching devices to a selectable tap transformer.

15. The system of claim 14, wherein said transformer tap controller is configured to output a voltage corresponding to a lowest tap setting when none of said switching devices are energized.

16. The system of claim 8, wherein said internal interface unit is accessible over the Internet.

17. The system of claim 8, wherein said internal interface unit is password protected.

18. In a system for regulating output and continuously and remotely monitoring measurements of reference cell potential or current for cathodic protection of a structure, a reference cell continuous monitor, comprising:

a means for removing noise, distorting effects, and residual components from said system, thereby producing a value for a true reference cell potential, wherein said value is provided regardless of whether or not said system has been shutdown.

19. The reference cell continuous monitor of claim 18, wherein said distorting effect is an IR drop.

20. The reference cell continuous monitor of claim 19, wherein said IR drop is a varying DC component from a full wave rectified line frequency being applied to said structure.

21. The reference cell continuous monitor of claim 18, wherein said noise is a component that appears as small negative approaching dips on leading edges of reference cell signal minimums.

22. The reference cell continuous monitor of claim 18, wherein said residual component is an un-rectified residual component of arbitrary phase delay.

23. The reference cell continuous monitor of claim 22, wherein said un-rectified residual component originates from a surrounding power grid.

24. A method for regulating output and continuously and remotely monitoring measurements of reference cell potential or current for cathodic protection of a structure, comprising:

providing one or more cathodic protection devices located proximate to said structure adapted to vary said output;

communicating with each of said cathodic protection devices using a central computer to remotely configuring each of said cathodic protection devices with a plurality of parameters, wherein each of said cathodic protection devices is queried at user set intervals; and

,

interfacing each of said cathodic protection devices with the Internet such that an operational history of each of said cathodic protection devices is available by way of an internet addressing scheme.

25. The method of claim 24, wherein one of said parameters includes how said current is being applied.

26. The method of claim 24, wherein one of said parameters includes a time constant for a shut-down decay rate.

27. The method of claim 24, wherein one of said parameters includes periodic shut-down cycle time intervals.

28. The method of claim 24, wherein one of said parameters includes adjustable limits for said output, wherein said output is an adjustable DC supply.

29. The method of claim 24, wherein one of said parameters includes a selection of event data logging.

30. The method of claim 24, wherein one of said parameters includes a variety of selectable control and annunciation schemes.

31. The method of claim 24, wherein for the step of communicating with each of said cathodic protection devices, a simultaneous shutdown of all of said rectifiers and controllers is coordinated.

32. The method of claim 24, wherein said operational history is password accessed.

33. In a system for regulating output and continuously and remotely monitoring measurements of reference cell potential or current for cathodic protection of a structure, a method for arriving at and regulating said reference cell potential, comprising the steps of:

providing a continuous monitor to remove distorting effects, residual components, and noise from said system to arrive at an amplitude for a DC bias;

correlating said DC bias with said reference cell potential;

initiating and timing a shutdown of said system to produce a decaying reference cell potential and a shutdown value;

providing a sampler to take a series of measurements of said decaying reference cell potential to produce a reference cell decay rate;

comparing said reference cell decay rate with a decay rate estimate;

comparing said shutdown value with said reference cell potential; and

,

utilizing a voting scheme to increment or decrement a DC supply or tap setting.

34. The method of claim 33, further comprising the step of providing a reference cell decay rate calculator utilizing curve fitting algorithms to determine said shutdown value.

35. A method for arriving at a true reference cell potential measurement devoid of noise, distorting effects, and residual components, comprising:

generating a sync signal;

establishing a sample collection window for said sync signal, wherein sample points of a reference cell signal are captured along minimums of said reference cell signal;

measuring said reference cell signal within said sample collection window, wherein said sample points of said reference cell signal are devoid of distorting effects and small, negative approaching dips on leading edges of said minimums;

passing said sample points through a moving average filter such that a residual line frequency component of each of said sample points is removed, thereby forming a DC bias of said reference cell signal; and

,

correlating said DC bias to said true reference cell potential measurement.

36. The method of claim 35, further comprising the step of comparing said true reference cell potential measurement to a measurement of a reference cell potential determined using a calculated shutdown.

37. The method of claim 35, wherein for the step of generating a sync signal, a slope transition event is detected on said reference cell signal.

38. The method of claim 35, wherein for the step of generating a sync signal, all DC components from a duplicated reference cell signal are removed.

39. The method of claim 35, wherein for the step of generating a sync signal, a non-rectified AC line reference signal is analyzed.

40. The method of claim 39, wherein said AC line reference signal is stripped of any DC component.

41. The method of claim 35, further comprising the step of applying a delay to said sync signal.

42. The method of claim 41, wherein said delay is applied by determining a midway point on at least one of said minimums of said reference cell signal.

43. The method of claim 42, wherein said midway point is determined by determining a width of a waveform of said reference cell signal when said waveform crosses a voltage threshold.

44. The method of claim 35, wherein said sample collection window is adjustable to establish bounds for each a sample start delay and a sample end delay.

45. The method of claim 44, wherein said sample start delay is positioned after each of said small, negative approaching dips.

46. The method of claim 44, wherein said sample start delay is positioned before distorting effects of an IR drop component.

47. The method of claim 44, wherein said sample start delay is positioned to account for a phase lag introduced to said reference cell signal by a rectifier transformer supplying power to a structure.

48. The method of claim 35, wherein the step of measuring said reference cell signal further comprises the steps of:

generating a series of pulses;

feeding said reference cell signal into a sample and hold section, wherein

said sample points are captured during each of said pulses.

49. The method of claim 35, wherein before the step of passing said sample points through said moving average filter, said reference cell signal is fed into a low pass filter to remove RF and other noise considered high frequency.

50. The method of claim 35, wherein said moving average filter is digital.

51. The method of claim 35, wherein said moving average filter is analog.

52. The method of claim 35, wherein said residual line frequency component is 60 Hz.

53. The method of claim 35, wherein said residual line frequency component is 50 Hz.

54. The method of claim 35, wherein said residual line frequency component is pulsed DC.