Preventing failure: Inspecting and cleaning energized utility equipment with thermal imaging and dry ice blasting

person and metal object cleaning house
A SPI powerline technician conducting dry ice blast cleaning of an energized 25 kV switching cubicle. The operator is wearing class-three rubber gloves and boots (not shown). It is important to have proper training and use proper PPE to eliminate the electrocution hazard

Thermal imaging combined with dry ice blast cleaning provides a newer and safer option for utility infrastructure inspection as part of preventative maintenance programs.

By Brett Fleming, SPI Inspections Inc., and Rob Milner, Teledyne FLIR

Following the near total grid failure in Texas during last winter’s record-cold temperatures, and with the increased occurrences of weather events around the world, utility customers and regulators are questioning utilities about the reliability of power infrastructure. Managers are being pressured as never before, as aging plants reach end of life. Capital and maintenance budgets are constantly under scrutiny. In response, power utilities across the world are taking stock and examining system resiliency in the face of climate change.

Meanwhile, proactive steps are being taken to strengthen the grid through inspections and regular maintenance performed to ensure power transmission and distribution systems can maintain reliability. Proactive maintenance is vital to ensure the reliability that customers expect while preventing outages that can cost millions—if not billions—in lost productivity and revenue.  

Proactive maintenance is more critical than ever. In a recent presentation of the American Society of Civil Engineers’ infrastructure report card, U.S. Secretary of Transportation Pete Buttigieg noted the U.S. received an overall “C-” grade for the condition of roads, bridges, ports, drinking water systems, and electricity grids, while highlighting an estimated $2.59 trillion spending gap in infrastructure.

The recent IPCC report update on climate change indicates high confidence that severe weather events are much more likely to occur compared to the past.  Previous one-in-50-year events are now expected to occur 4.8 times within a 50-year span, rising to 8.6 times per period in the foreseeable future.  Regional extreme weather phenomena: tornadoes in the Midwest; hurricanes along the coast; drought and wildfires in California; flooding, ice storms, lightning, or winter storms in Texas, will all continue to affect the power system at an increasing rate. 

Maintaining electrical infrastructure by leveraging new and existing inspection technologies and cleaning equipment is a key component of a strategy to minimize grid disruption.

Reducing Costs Through Proactive Maintenance

Proactive maintenance programs will always be less expensive in the long run. Replacement of components can be factored in and planned for, leading to fewer customers out of power, less overtime paid, lower shipping costs, and reduced injury rates. As critical infrastructure, the work will be completed ether way, but the costs of emergency restoration or unplanned maintenance is always much higher, and the hazards in the field increase exponentially with the severity of failure.

Regulatory bodies in most areas require an inspection be completed on an annual basis. Working thermal imaging into the inspection and cleaning cycle does not add significantly to the overall cost, while making a night-and-day difference to the safety and reliability of the system.

Address Maintenance Proactively Through Thermal Imaging

A proactive, predictive maintenance program potentially requires examining hundreds or even thousands of utility switching cubicles across a given operational area. This presents a daunting task for utility operators, especially rural and smaller operators who don’t have the resources, staff, or equipment to execute an effective program. However, by combining high-definition thermal imaging inspection with proprietary dry ice blasting tools to clean hot, high voltage switching cubicles, utilities now have a safer, more cost-effective method to efficiently inspect utility cubicles and clean the equipment all at once.

Developed by SPI Inspections, a Canadian-based inspection and field services company specializing in maintenance of power infrastructure, the process starts with a thermal inspection. Using a high definition FLIR T540 thermal imaging camera paired with SPI software, any problematic equipment is quickly located. By leveraging the T540, SPI can inspect voltage utility equipment in a third of the time versus traditional methods, capturing thermal, visible light, and a combination of the two through the FLIR multispectral (MSX) imaging processing capability. This process overlays the edge detail of the visible image on the thermal image for added context and detail. That data can then be packaged into a report and sent to the cloud or other devices for further processing and storage.

thermal image
Figure 1 – Example of a lightly overloaded 4160V switching cubicle. The customer requires that a 30 degrees Celsius temperature differential, be serviced. In this case the condition was noted, and it will be watched for changes going forward. On inspection day the ambient air temperature was negative 16 degrees Celsius

For example, dirt and dust tend to gather on transformer windings or insulators and may prevent the free flow of air that’s needed to keep the transformer operating smoothly and efficiently. This can be difficult to inspect with the naked eye, hence the need for thermography equipment as a crucial first step in evaluating a transformer before cleaning.

As part of this preventative maintenance inspection, SPI software can also provide crucial context to those without thermography expertise to identify potential problem areas via a color scale: green means the equipment is operating at a normal temperature; yellow suggests anomalous heat where potential repairs might be required; and red denotes a very hot piece of equipment that needs to be addressed immediately, typically running upwards of 30 degrees Celsius above normal.

Through this inspection process, SPI has found that proactively addressing yellow-denoted issues can be anywhere from 10 to 40 times less expensive to repair than issues in the red zone where immediate action is required. This system provides utilities with an action plan to proactively replace parts during regular maintenance schedules to avoid costly blackouts and cost overruns.

report
Figure 2: Example report where green means the equipment is operating at a normal temperature; yellow suggests anomalous heat where potential repairs might be required; and red denotes a very hot piece of equipment that needs to be addressed immediately, typically running upwards of 30 degrees Celsius above normal.

The Dry Ice Blasting Process

Once the inspection of the switching cubical is complete, SPI has developed dry-ice blasting tools that can be used for live-front equipment that is safe to operate by eliminating the potential for arc-flash issues up to 72,000 volts.

Dry ice blasting (see lead image) has proven to be a superior method to prevailing cleaning methods, including the use of hazardous solvents or common corn blasting techniques. Corn blasting ultimately makes it impossible to completely clean the cubical, as bits of corn are left behind and become food for small rodents and other wildlife that may also chew through high voltage wires, causing fires and dangerous conditions for workers near the equipment and even children who might play close by.

The SPI tool shoots dry ice at the speed of sound at negative 79 degrees Celsius. The dry ice quickly expands more than 400 times its volume as it sublimates onto the surface of the equipment, peeling away grime while leaving the paint and insulating material intact after it evaporates. In contrast, corn blasting techniques leave behind edible bits of corn that can attract animals, potentially generating a host of new maintenance issues.

chart and graph
Figure 3 – SPI recently conducted an inspection and dry ice blast cleaning on underground switching cubicles for a utility in Alberta, Canada, along with a thorough inspection via a FLIR T540 thermal imaging camera. The switching cubicles were 25 years old, and the utility did not have a proactive inspection and maintenance program in place. The inspection was prompted as a result of two arc-flash incidences in the previous year. The results of the inspection were clear: 60 percent of the cubicles required some form of repair to bring them up to standard; a further 10 percent required major repair such that it was unsafe to continue using the equipment until repairs could be completed; only 30 percent of the cubicles passed the safety inspection. SPI uses thermal imaging to identify potential hazards prior to beginning the cleaning process with safety as the primary concern. By conducting a thermal scan beforehand, inspectors can avoid a catastrophic failure for staff. Following up with a thermographic scan also helps proves that the site has been properly cleaned and inspected.

As this system does not require any equipment power shutoff, it can be completed at virtually any time of day and any part of the year, including during extreme cold weather, providing utilities maximum flexibility to conduct inspection and maintenance procedures with limited disruption to the grid. For any required equipment replacement resulting from the before-and-after thermal inspection, utilities have more reliable information to make repair decisions.  

Saving Money and Maintaining Uptime Through Predictive Maintenance

Ultimately, the true value of having a single procedure for inspection and cleaning without needing to power down equipment is the long-term savings. Potentially tens of millions of dollars can be saved across many years, depending on the size of the operation. That savings is accrued both in terms of maintaining uptime for the customer, and through planned replacement costs for aging equipment and obsolescence. If utilities can create and maintain a proactive maintenance schedule, they can plan to perform major fixes when they can, and not when they must, all the while ensuring the safety of inspection and cleaning personnel.

Key Takeaways:

  • Thermographic imaging prior to the commencement of work adds a margin of safety while helping quickly and easily identify deficiencies in utility equipment.
  • Thermal imaging also makes it possible to identify moderately overloaded equipment and poor neutral connections before this becomes an issue.
  • Dry ice blasting is the process for cleaning electrical utility infrastructure, including switching cubicles, transformers, insulators, substation equipment, and more.
  • Dry ice blasting is especially good at cleaning energized equipment. It is superior to other methods of media cleaning, and it eliminates the need for dangerous, environmentally harsh solvents or the use of corn that can lead to new problems with critter infestation.
  • Dry ice blasting meet environmental goals as the dry ice media is 100 percent recycled from industrial processes.
  • Thermal imaging, after work has been completed, verifies that the system is operating at peak efficiency. This provides proper documentation to present confirmation to utility operators.

About the Authors

Brett Fleming

Brett Fleming has more 32 years of experience building, commissioning, and inspecting power systems, serving as the co-founder and corporate director of SPI Inspections, an Edmonton, Canada-based firm focused on providing specialized utility system infrastructure inspections and field services across North America and China. He is also a Journey Certified Powerline Technician with more than 13 years of experience as a post-secondary trade’s instructor.

Rob Milner

Rob Milner is a global business develop manager, condition monitoring, for Teledyne FLIR, part of Teledyne Technologies Incorporated. His career at Teledyne FLIR spans more than 20 years across various sales and business development roles within multiple vertical markets, including utilities. He holds a master’s degree in metallurgical engineering from the Queen’s University in Canada. 

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