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US 6,617,855 B2Granted
Pipeline mapping and interrupter therefor
AssigneeRadiodetection Limited
InventorsDavid William Flatt, Stephen John Petherick, Robert Ashworth Worsely
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AssigneeRadiodetection Limited
InventorsDavid William Flatt, Stephen John Petherick, Robert Ashworth Worsely
Estimating the term…
Cathodic protection voltages are used to resist the damage to pipes or cables from electrolytic effects. However, localised fields can lead to stray currents and may result in corrosion and it is therefore desirable to detect and analyse those stray currents. Frequently there are several pipes in the area of interest and so it is necessary to distinguish between those pipes. Therefore the cathodic voltage on the pipes is modulated, with different pipes having different modulations. This modulation may be applied using an interrupter. Orthogonal modulations with non-unitary aspect ratios improve the discrimination between the pipes whilst maximising the energy content of the modulation pattern. The analysis is improved when the interrupters are synchronised with each other and so repeating on the same time-base. This synchronisation may be achieved using an external time signal such as GPS. An interrupter which can be used in this regard is also proposed, and may be powered from the cathodic voltage itself.
A method of identifying underground pipes or cables by detecting currents on one or more said underground pipes or cables comprising:
Apparatus for identifying underground pipes or cables by detecting currents in one or more of said underground pipes or cables to which a modulated negative voltage is applied in order to produce one or more modulated currents on the or each of said pipes or cables, apparatus comprising:
A system according to claim comprising a plurality of interrupters, each interrupter arranged to modulate a different pipe or cable, and the interrupters are each arranged to be synchronised with each other.
An apparatus for identifying underground pipes or cables by detecting currents in one or more of said underground pipes or cables to which a modulated negative voltage is applied in order to produce one or more modulated currents on the or each of said pipes or cables, apparatus comprising:
Dependencies are inferred from the claim text.