Ensuring a plant's electrical system safety
One company's experience with infrared thermography
This article takes a look at using infrared thermography in the plant setting to detect potential fire hazards. It discusses who can provide the service, what sorts of problems it can detect, and generally explains how the problems discovered when using this technology should be handled. It also uses an actual inspection as a basis for the discussion.
Many people work in buildings that were constructed more than 40 years ago. At the time they were built, no one could have imagined the power requirements of the 21st century.
An older plant has much more equipment today than it did when it was built, and each piece of equipment pulls more power than was previously required. Computers on every desktop and dozens of printers and copiers throughout a building add to the power usage.
To make matters worse, the typical older plant has been expanded many times, and each time electrical systems simply were added to the original electrical infrastructure. Can the existing electrical system support all the current requirements? What electrical fire hazards are hidden within the walls and ceilings?
This was the situation we found ourselves in recently. Our worries were compounded when we learned that fires have caused more physical plant damage in the past three years than any other single hazard.
We needed a way to verify that our electrical system was safe and to identify potential problems before they became fire catastrophes. As we wrestled with how to accomplish this, we were approached by a representative from our local power company who suggested that we have an infrared thermography inspection.
Inspection With Infrared
Infrared thermography takes thermal radiation from electrical and mechanical systems and converts it into an electronic image or picture. This allows for the detection of problems before these temperatures reach the point at which they can cause an electrical outage or, worse yet, a catastrophic fire.
Infrared thermography also can be used to evaluate roof systems for leaks; to detect problems in steam traps and valves in piping systems; to survey buildings for energy leaks; to examine furnace refractories for gaps and voids; and to detect damaged bearings in motors, pumps, and other rotating machinery.
We were fortunate that our local power supplier, Carolina Power and Light, provided an infrared thermography service. As part of this service, the power company representative came to our plant and, working hand in hand with our maintenance group, surveyed our entire electrical system.
We dictated the extent of our survey. It could be as limited as reviewing only junction boxes and power distribution points or as extensive as reviewing every wire in the plant. In our case, to review all office wiring (10,000 sq. ft.) and all panels throughout our 119,000-sq.-ft. plant took one day. The length of the inspection will vary with the complexity and size of the electrical system to be reviewed.
In some areas power companies do not offer infrared thermography services, leaving companies to search out their own service providers. An inquiry to a local electrical contractor usually can yield information about a service provider in a given area.
Categorizing and Solving Problems
During an infrared thermography inspection, problems are divided into three categories:
1. Minor problems, in which temperatures have risen no more than 36 degrees F above the ambient temperature, require corrective action as scheduling permits.
2. Serious problems — those causing temperature increases of 36 to 90 degrees F above ambient — require corrective measures as soon as possible.
3. Critical problems, in which temperatures have risen more than 90 degrees F higher than the ambient temperature, are considered urgent and require immediate corrective measures. In some cases use of these circuits should be discontinued until repairs are made.
Minor problems can be caused by poor splices in wiring, loose or corroded connections or conductors, loose wires, or load imbalances. Undersized components or loose or corroded conductors can lead to serious or critical problems if left uncorrected.
Our infrared thermography inspection revealed nearly a dozen minor, serious, and critical problems. We determined solutions as each problem was identified and classified. All problems were resolved within a matter of weeks, and we could then operate with peace of mind, knowing that our electrical systems were reliable, capable, and safe.
To ensure the continued safety of our electrical infrastructure, we have decided to reinspect all systems, with the help of our local power company, on an annual basis. By inspecting annually with infrared thermography, we can anticipate problems long before they become potential fire hazards.
The FABRICATOR is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The FABRICATOR has served the industry since 1971.