Non-invasive, high resolution detection of electrical currents and electrochemical impedances at spaced localities along a pipeline
First Claim
1. A non-invasive method for detecting electrical current flow characteristics in a circuit having local regions of an electrically conductive object buried in an electrolyte, the method comprising:
- (a) impressing an alternating electrical potential, which contains a plurality of frequencies, between the buried object and an electrode which is buried in the electrolyte and spaced from the object; and
(b) detecting the alternating magnetic field induced by electrical currents injected into said circuit by the electrical potential and detecting both the phase and the amplitude of the field for each of the impressed plurality of frequencies and the storing the phase and storing the amplitude in a memory for each of the impressed frequencies, the field being detected along at least one selected spatial axis at the frequencies of potential impression to detect electrical current at a local region of the circuit as a function of frequency.
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Abstract
Electrical current distribution in the soil surrounding a buried pipeline is detected by applying an AC electrical potential between the pipe and a buried electrode spaced from the pipe. The magnetic field at spaced localities along the pipe arising from currents transverse to the pipe is detected. Additionally, a potential containing a plurality of alternating frequencies is similarly applied to the pipe and the magnetic field induced by the resulting electrical current both along the pipe and transversely of the pipe is detected. The magnetic field is detected by correlation discrimination at spaced locations along the pipe and across the spectrum of the impressed frequencies. The detected data is used to determine the capacitance and resistance of the soil/pipe interface at localities along the pipe and to generate impedance plots which indicate characteristics of that interface.
80 Citations
24 Claims
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1. A non-invasive method for detecting electrical current flow characteristics in a circuit having local regions of an electrically conductive object buried in an electrolyte, the method comprising:
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(a) impressing an alternating electrical potential, which contains a plurality of frequencies, between the buried object and an electrode which is buried in the electrolyte and spaced from the object; and (b) detecting the alternating magnetic field induced by electrical currents injected into said circuit by the electrical potential and detecting both the phase and the amplitude of the field for each of the impressed plurality of frequencies and the storing the phase and storing the amplitude in a memory for each of the impressed frequencies, the field being detected along at least one selected spatial axis at the frequencies of potential impression to detect electrical current at a local region of the circuit as a function of frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus for detecting AC electrical current flow characteristics in a circuit having local regions of an electrically conductive object buried in an electrolyte, the apparatus comprising:
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(a) a vector magnetometer for detecting the magnetic field induced by the current in the circuit at the magnetometer location; (b) potential source means connected between the buried object and an electrode buried in the electrolyte, the source means signal containing a plurality of frequencies; and (c) detector means connected to the magnetometer for detecting the component magnetic field amplitude and phase at the frequencies of the AC current wherein the detector means includes an analyzer means for detecting the amplitude and phase of the magnetic field at each of said source means signal frequencies. - View Dependent Claims (17, 18, 19)
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20. A non-invasive method for detecting electrical current flow characteristics in a circuit having local regions of an electrically conductive pipe buried in an electrolyte, the method comprising:
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(a) impressing an electrical potential signal, which is alternating at at least one selected frequency, between the buried object and an electrode which is buried in the electrolyte and spaced from the object; and (b) detecting at least one signal representing the alternating magnetic field, which is induced by electrical currents which are injected into said circuit by the electrical potential at at least one location along the buried object; and (c) correlation discriminating a transfer function from two of said signals representing the complex impedance between the buried object and the electrode at the location of the detected magnetic field. - View Dependent Claims (21, 22, 23, 24)
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Specification