A Brief History on Monitoring and Datalogging Dynamic CP Events
As urban areas expand and infrastructures electrify, cathodic protection professionals are increasingly focused on the potential impacts of interference from adjacent infrastructures, such as high voltage AC powerlines and dynamic DC interference from transit systems. Short in duration, dynamic events can create suboptimal conditions for safety and present conditions for accelerated and acute corrosion.
Now while dynamic threats have been known for some time, they’ve remained a challenge to properly record and to establish visibility into in near real-time. The first technologies used to record these events included chart records, which relied on vibrating pens to visually track the parameter readings measured on a site. Chart recorders evolved into more compact ticker-tape recorders, but the core concept was the same. Both would require manual review of a CP specialist, which must have been quite a task!
However, in the late 90s and early 2000s, the emergence of computing power and digital storage led to the introduction of electronic dataloggers, which eventually became specialized for cathodic protection applications. Dataloggers have dominated the event monitoring landscape since, becoming key tools for engineers to gather data during surveys and for analysis during design exercises. Rugged, small, and versatile, these loggers can be dropped into just about any scenario imaginable in the industry. However, a major drawback for portable dataloggers is that an operator is effectively blind from the moment that they have installed the logger and walked away from it, until a point in the future when the operator returns to download the data for analysis. Simply put, traditional dataloggers haven’t increased the level of near real-time visibility into the impact of dynamic events onto protection levels.
Datalogging Evolved
New technology represents a technological evolution whereby the best elements of portable dataloggers have been blended with the best elements of permanently installed remote monitoring units, creating a new category of device, the remote data logger [RDL]. The RDL allows operators to gain remote visibility into the performance and state of their protection systems while capturing high volumes of data that are granular enough for forensic and diagnostic analysis. Capturing samples in two parallel paths, the device monitors desired parameters on a scheduled basis, typically from hourly to daily, while fast sample events can be configured to run in parallel. Fast sample rates range generally from 1 sample per second to 1 sample per minute, but depending on the application engineers can configure to be more or less frequent.
Increasingly Remote Visibility for Dynamic DC Interference
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With many cities and municipalities developing electrified light rail transport networks, dynamic DC interference from these systems is an increasingly common threat to protected pipelines. As a train passes through a pipeline corridor, it is not uncommon to see a short-duration influence on the DC current and voltage on steel assets in the vicinity. If these effects are large amplitude and frequent, they can cause considerable damage to a pipeline coating and potentially lead to rapid corrosion.
Each site will have a unique make up, from geometry to protection system type, to mitigation systems and assets available as monitoring points. In some instances, mitigation can consist of grounding cells that offer a low resistance pathway to ground to the DC current spikes, minimizing the effect on the pipeline itself. In other instances, reverse current switches can provide a one-way control for current to dissipate.
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In this implementation, an RDL is monitoring current passing through a reverse current switch in close proximity to a DC powered transit line. The logger is sampling at 1 sample per second, 24-hours per day, continuously, and sending fast sample event dataset to the cloud every 24 hours [see Figure 1].
At this resolution, an approximate idea of the amplitude of oscillating DC Current that is passing through the reverse current switch is provided. With spikes upwards of 200 A DC, interference is significant. Furthermore, the period of time between 12am and 4am, when trains are not scheduled on this system, provides a low-period baseline [see Figure 2].
Zooming into a 2-hour timeframe around rush hour provides a more specific view into the shifts in DC current on the asset. These spikes have been compared with local transit schedules and are a good reflection of passing trains.
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Even more analysis is possible when stitching multiple daily fast sample events together. The following illustrates the diurnal pattern over a 1-week period [see Figure 3].
Flexibility can Improve Project Workflow
With next generation remote dataloggers, flexibility is provided to the user such that they can change the datalogging configuration remotely, which greatly expands how a datalogging ‘event’ can be calibrated depending on the level of knowledge that is known about a site going in.
How this could work in practice is as follows. At the initial outset of the project, a RDL is configured to fast sample continuously at a sample rate of 1 sample per 20 seconds. After one week, an initial analysis of the fast sample data files provides a holistic overview of network dynamics, such that specific days or the week, or times of the day, can be targeted in a deeper dive. A new fast sample command can be sent remotely, initiating a sample rate of 1 sample per second, providing much more granularity than before. In some instances, an engineer may want to take it even further. Say that the waveform of a passing train could be understood more completely – configuring the device to read at a 10Hz sample rate, or 10 samples per second – the engineer grabs a detailed snapshot of a series of train passes.
Mapping Out the Broader Benefits
With remote datalogging in place, near real-time data can be accessed and viewed via the cloud from any internet connected device. Beyond the immediate impacts of reducing human errors around device installation and configuration, this allows for alarms to be established based on specific limit thresholds. If a mitigation asset stops working, or shows signs of deterioration, an alert can dramatically improve the response time for an operator. Beyond this, the potential is myriad. Key categories of benefit that should contribute towards reduction of risk and improved outcomes for field personnel and the public, include:
- Increasing visibility into dynamic events
- Leading to quicker response times and risk reduction
- Improving data quality to inform design and mitigation practices
- Improving regulatory reporting around dynamic issues
- Improving worker safety
- Eliminating mobilization to remote assets to install/uninstall portable dataloggers
- Reducing premature mobilizations
- Reducing windshield time getting dangerous places
- Increasing operating efficiency
- By reducing unnecessary days waiting for depolarization
- Reducing time technicians and consultants are performing low-value activities such as driving and configuration
MOBILTEX’s CorTalk RMU Platform Solutions remotely execute complete GPS-synchronized interruption on a series of rectifiers and test points in order to make cathodic protection surveys simpler and more accurate than ever before. MOBILTEX offers a holistic approach to cathodic protection monitoring, so you can capture and maintain detailed records of rectifier outputs, test station ‘on’/‘off’ values, coupon readings, and more. MOBILTEX solutions are also being used to monitor and alert operators to potentially catastrophic CP interference from high-voltage power lines (HVPLs) and Transit systems, including Fast Sampling capabilities at challenging at-risk applications. In addition, forward-thinking operators are leveraging this efficient backhaul to add additional remote sensing technologies in areas that have been cost-prohibitive or technically impossible in the past.
The MOBILTEX CorView Cloud Platform works as an all-in-one cathodic protection data management system, ensuring you can easily access complete and reliable compliance records that meet all the data retention requirements of Part 192 of the PHMSA regulations. CorView gives operators round-the-clock access to any of the data collected by MOBILTEX’s full portfolio of RMUs.
Refer to the list below for a quick reference of features available in the CorTalk RMU solutions and Contact a MOBILTEX representative today to find out how our products can improve safety, lower operating costs and future-proof your operations, all while optimizing the performance of your cathodic protection systems.
| PRODUCT | FEATURES — APPLICATIONS |
| CorTalk RDL1 +INT1 | Fast Sampling at Test points & Rectifiers : GPS Sync’d Interruption; Potential Readings; Single or Double Coupon Readings, Bond Readings — APPLICATIONS: Test Station Monitoring w/ Telluric and Dynamic Current; AC Interference & Mitigation Monitoring; HVAC/HVDC Fault Monitoring; Depolarization Surveys; Dynamic DC Interference at LRT Crossings; Monitoring for Baseline During Surveys (ie. Tellurics) |
| CorTalk RMU1+INT1 | Test Point Remote Monitoring : GPS Sync’d Interruption; Potential Readings; Single or Double Coupon Readings, Bond Readings; Automated AC Peak Detection |
| CorTalk RMU3 | Rectifier Remote Monitoring : GPS Sync’d Interruption; Voltage Output Readings, Current Output Readings; Structure-to-Electrolyte Potential Readings; PCR/SSD monitoring; Structure Instant Off |
