Modulator Unit for Wireless Cathodic Protection Current Mapping
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Solution Overview
Problem
Current methods for assessing cathodic protection along metallic pipelines are inefficient, requiring large portable transmitters, multiple setups, and cannot accurately represent the applied DC current due to interference and limited range, lacking remote control and integration with existing remote monitoring units.
Innovation Solution
An apparatus that integrates a modulator unit with a transformer rectifier unit to generate a current mapping signal directly derived from the impressed cathodic protection current, allowing wireless detection and remote control, enabling efficient assessment of corrosion protection along longer pipeline lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If portable transmitters are used to generate current mapping signals, then measurements can be taken above ground, but the equipment is large, requires multiple setups, and has limited range
Solution Approach 1:
The patent combines the modulator unit with the existing remote monitoring unit (RMU) that is permanently installed at the pipeline. This integration eliminates the need for separate portable transmitter equipment, reducing device complexity while maintaining measurement capability. The RMU's permanent installation provides stable, long-range coverage without requiring multiple setups.
Solution Approach 2:
The system uses the pipeline's own cathodic protection current as the source for generating the current mapping signal. The modulator unit modulates this existing current rather than requiring an external signal source. This self-service approach eliminates the need for portable transmitters and external equipment, simplifying the overall system while maintaining measurement accuracy.
2Measurement precision
If DC current is measured directly in the pipeline, then accurate corrosion protection assessment is obtained, but earth's magnetic fields and interference prevent remote or wireless measurement
Solution Approach 1:
The patent introduces an AC carrier signal as an intermediary to transfer information about the DC cathodic protection current. The modulator unit modulates the DC current onto the AC carrier, creating a signal that can be wirelessly transmitted through the pipeline. This intermediary approach allows remote detection while preserving the accuracy of the original DC current measurement.
Solution Approach 2:
The system changes the measurement parameter from direct DC current measurement to modulated AC signal detection. By modulating the DC cathodic protection current onto an AC carrier wave, the system converts the difficult-to-measure DC parameter into an easily detectable AC signal that can be transmitted wirelessly and measured remotely without interference from earth's magnetic fields.
3Measurement precision
If manual measurements are taken along the pipeline, then corrosion protection levels are assessed, but the process is inefficient and time-consuming
Solution Approach 1:
The patent enables continuous current mapping along the pipeline through permanent installation of the modulator unit at the RMU location. The system can continuously or periodically transmit modulated signals along the entire pipeline length, allowing for ongoing monitoring without the interruptions and setup time required by manual measurement methods. This continuous operation significantly improves measurement efficiency and productivity.
4Ease of manufacture
If AC signal is applied for pipeline location, then the pipeline can be detected above ground, but the signal does not represent the DC cathodic protection current due to impedance differences
Solution Approach 1:
The patent uses periodic modulation of the DC cathodic protection current onto an AC carrier wave at a specific frequency. This periodic action creates a distinctive signal pattern that can be easily detected for pipeline location while simultaneously preserving the characteristics of the original DC current. The modulation frequency is chosen to distinguish the signal from background noise while maintaining fidelity to the cathodic protection current being measured.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and efficient wireless measurement of cathodic protection current along pipelines, reducing the need for direct connections and multiple transmitters, with a signal that accurately represents the applied protection current, improving assessment and monitoring capabilities.
Implementation Method 1
the modulator unit is operable to receive the impressed cathodic protection current from the transformer rectifier unit and to modulate the impressed cathodic protection current to produce a current mapping signal which is applied to the metallic structure
Implementation Method 2
the current mapping signal flowing in the metallic structure can be detected and measured wirelessly from above ground
Data Source
AI summary
The present invention relates to apparatus for connection to a transformer rectifier unit which is operable to output an impressed cathodic protection current for cathodic protection of a metallic structure located below ground, the apparatus comprising:a modulator unit in connection with the transformer rectifier unit and arranged for permanent electrical connection with a metallic structure, wherein when the apparatus is in use the modulator unit is operable to receive the impressed cathodic protection current from the transformer rectifier unit and to modulate the impressed cathodic protection current to produce a current mapping signal which is applied to the metallic structure, such that the current mapping signal flowing in the metallic structure can be detected and measured wirelessly from above ground, and wherein the current mapping signal is directly derived from, and corresponds to, the impressed cathodic protection current, and wherein the modulator unit is operable to be controlled remotely. The present invention further provides a method of surveying the impressed cathodic protection current in an underground metallic structure using the aforementioned apparatus.