Vision aids power transmission
Jon Titus, Contributing Technical Editor -- Test & Measurement World, 12/1/2003
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A video sagometer at the Long Island Power Authority includes several components that monitor the health of a power-transmission line. |
In particular, they use a video "sagometer," developed jointly by the Southwest Research Institute (www.swri.org) and EDM International (www.edmlink.com). A sagometer, which includes a camera, a vision system, a weather station, and a communication link, visually monitors the sag in a power line. (A small target on the power line provides the visual measuring point.) But what does this sag have to do with power transmission?
All power lines sag due to gravity, and power passing through a conductor increases sag due to thermal expansion. (Some power lines operate at up to 100°C.) Temperature and wind also affect sag. Too much sag may damage a power line, yet reducing power that contributes to sag may lead to power shortages. So, power companies must balance the need to transmit more power against the health—and life—of their lines.
A video sagometer lets a company check remote line conditions in real time so it can optimize power transmission. After a sagometer determines the visual position of the line it's monitoring, software calculates the height of the power line based on current conditions and calibration measurements made during target setup. Then, after the sagometer transmits its data, software at a receiving station relates height and environmental data to sag limits, ground clearances, and power-carrying capacities. By using this information, a transmission company can adjust power transmission in real time to meet customer needs and still operate within prescribed limits.
Using machine-vision techniques to monitor power lines isn't an obvious application. We usually think of vision systems as those that monitor PCBs and cell-phone displays on a production line. But creative engineers will always find new ways to solve unusual "visual" problems.
For more information on cameras, visit www.tmworld.com/ins.
Jon Titus, Contributing Technical Editor jontitus@comcast.net
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