What is Freezing Rain
Freezing rain occurs when liquid raindrops formed in a layer of warm air well above the surface fall into a layer of freezing air above the ground. If the layer of freezing air is thin enough, raindrops do not have enough time to freeze before reaching the ground. Instead, the water freezes on contact with a surface, creating a coating of ice on whatever the raindrops touch.
Freshly fallen snow and heavy rain can all make a rush-hour commute frustrating, but freezing rain is perhaps the most deceiving and destructive of all winter precipitation. Power lines coated with ice become extremely heavy (just 1/4 of an inch of accumulated ice can add about 500 pounds (230 kg) of weight per line span), causing support poles, insulators and lines to break. Due to it being benign rain initially, the onset of freezing rain may be completely missed until it begins to accumulate as ice.
Numerous de-icing methods to remove the ice from a particular surface exist but to make them effective, continuous monitoring of temperature and the sag of parts of the power system for obtaining real-time data is required, particularly in remote areas with difficult access.
Comtrade has developed a prototype to prove that Itron Riva can be used in combination with cost effective sensors to deliver real-time monitoring of power lines sag caused by ice buildup, temperature or any other sensor measurement in the field.
Ice Buildup monitoring solution based on Itron Riva
A simple and cheap yet robust flex sensor is installed on certain points of the power line and connected to an Itron Riva node. The sensor’s resistance changes when it is bent and can thus be used to measure power line sag due to forming ice. Itron Riva nodes make up the Itron Riva Adaptive Communication Technology (ACT) Mesh that is used to send sensor values periodically to the Itron Riva root, which acts as an aggregator gathering data from its nodes. It then uploads the data to any cloud (e.g. MS Azure) where it can be processed. By analyzing the sensor values displayed on a graph, it can be easily determined whether the sag effect is due to ice or some other effect (such as birds, wind, etc.).
The same setup can be used to employ temperature, lightning strike, wind, humidity, or any other sensor for different applications, such as detection of wire sag due to heat, faster intervention after a lightning strike, etc. Predictive algorithms can then be employed to predict a chance of power line failure based on historic data well before the event occurs thus giving maintenance teams more time to react.