Method of identifying a buried cable by applying a low frequency signal to the cable and detecting the resultant field
First Claim
1. A method of identifying a cable buried underground comprising the steps of:
- (a) electrically isolating the cable;
(b) applying a voltage signal to the cable, the voltage signal having non-zero frequency less than 10 Hz;
(c) bringing an electric field sensor into proximity with the cable; and
(d) detecting the electric field due to the voltage signal using said sensor.
1 Assignment
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Accused Products
Abstract
In order to identify a cable buried underground, a very low frequency voltage signal is applied to the cable and an electric field sensor is brought into proximity with the cable. The sensor thus detects the voltage signal on the cable and so identifies the cable. The sensor is unaffected by one or more additional cables carrying voltage signals, which are proximate the cable of interest, as the electric filters from such additional cables do not pass to the cable of interest. The sensor is mounted on a probe which is mounted into a bore in the soil around the cable of interest. The probes may also carry a magnetometer for detecting magnetic fields generated by low frequency alternating current signals on the cable of interest.
115 Citations
12 Claims
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1. A method of identifying a cable buried underground comprising the steps of:
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(a) electrically isolating the cable; (b) applying a voltage signal to the cable, the voltage signal having non-zero frequency less than 10 Hz; (c) bringing an electric field sensor into proximity with the cable; and (d) detecting the electric field due to the voltage signal using said sensor.
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2. A method according to claim 1 wherein said step of bringing the sensor into proximity with the cable includes forming a bore from the surface of the ground to the cable and inserting the sensor into the bore.
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3. A method according to claim 1 wherein the sensor is brought into contact with the cable.
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4. A method according to claim 1 wherein said voltage signal has a modulation applied thereto.
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5. A method according to claim 1 further including the steps of:
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(e) applying a current signal to the cable, the current signal having a non-zero frequency less than 1OHz; (f) bringing a magnetic field sensor into proximity with the cable; and (g) detecting the magnetic field due to the current signal using the sensor.
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6. A method according to claim 5 wherein said current signal has a modulation applied thereto.
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7. A method of locating or identifying a cable buried underground comprising the steps of:
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a. applying a current signal to the cable, the current signal and all of its components having a non-zero frequency less than 10 Hz; b. bringing a magnetic field sensor into proximity with the cable; and c. detecting the magnetic field created by the current signal using the sensor.
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8. A method according to claim 7 wherein the step of bringing the sensor into proximity with the cable includes forming a bore from the surface of the ground to the cable and inserting the sensor into the bore.
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9. A method according to claim 7 wherein said current signal has a modulation applied thereto.
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10. A method of identifying a cable buried underground comprising the steps of:
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(a) applying a current signal, to the cable, the current signal having all of its components at a non-zero frequency that are less than 10 Hz; (b) bringing a magnetic field sensor in the proximity with the cable without circumventing the cable; and (c) detecting the magnetic field created by the current signal using the sensor.
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11. A method according to claim 10 wherein the step of bringing the sensor into proximity with the cable includes forming a bore from the surface of the ground to the cable and inserting the sensor into the bore.
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12. A method according to claim 10 wherein said current signal has a modulation applied thereto.
Specification