Une coopérative électrique du Wisconsin intègre la thermographie
Using a handheld infrared imager, Keith Weyh, technical services supervisor at Adams Columbia Electric Cooperative, monitors the health of the co-op's equipment, the equipment of its members, and sometimes even the equipment of the transmission company supplying its substations.
Until early in 2004, ACEC contracted with Wisconsin Public Service Corporation (WPSC) to do the co-op's thermography (or thermal imaging). Annually, a WPSC technician used a thermal imager - also called an infrared (IR) camera - to make two-dimensional representations of the surface temperatures of equipment in the co-op's substations. What those images sometimes revealed were hot spots on the equipment, which typically means a component is likely on its way to failure and should be serviced.
If an inspection uncovered what appeared to be a critical problem, a supervisor was called to request that a line crew make repairs. There was no provision for follow-up imaging to determine if effective repairs were made. In one case, it was two years between the detection of a failing regulator and confirmation that it had been repaired.
Justifying a camera purchase Clearly, the outsourced, once-a-year inspections were not getting the job done. That fact - and several other factors - led to the decision to bring thermography in house.
One important issue was the need to protect expensive equipment. Another factor influencing the decision to stop outsourcing thermal imaging was the desire to reduce overtime work caused by outages. Given these considerations, ACEC management set about securing an IR camera for the organization with the understanding that Keith Weyh would do most of the thermography.
Weyh, a long-time lineman and the co-op's current technical services supervisor, assisted in the selection process.
Thermal imaging at ACEC With no formal training, Weyh was able to begin using the new camera right away. He attributes his ability to do that to his years of experience in the electric utility service sector, his experience using a handheld, non-contact IR thermometer, and personal research. Weyh says that training might be helpful, but what he looks for with the IR camera is pretty simple. One just needs to understand emissivity - or in other words, understand that not all energy emanating from an object is emitted by the object - and then know what to do in situations where reflected heat may be affecting an IR image.
Today, Weyh, armed with this knowledge and his thermal imager, inspects the co-op's equipment, the equipment of members and sometimes even the equipment of the transmission company supplying power to ACEC's substations. Here, in part, is what he inspects and how: Substations.
Problems and pitfalls Asked what on-the-job problems he encounters while doing thermography at ACEC, Weyh mentions the following:
Difficulty doing trending.
False positives due to ambient heat.
False positives due to low emissivity.
Inaccessibility due to wildlife guards.
Asked to sum up his experience with a thermal imager, Weyh says, "It has been a good tool. My thoughts are that eventually we are going to catch up, and I'm not going to be finding as many problems." Then he laughingly adds, "Hopefully, I'll work myself out of a job," but quickly notes, "No, the camera will always have a use here."
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