Electrical arcing 'basically melted' LRT power line after January ice storm
The LRT system had withstood more than 50 similar freezing rain events without any problems, a city official said Thursday.
Blair Crawford, Ottawa Citizen
Published Feb 09, 2023 • 3 minute read
Fog rolling off the open Rideau River near Lees Station condensed and froze to the LRT’s overhead power lines in the area during a Jan. 4 freezing rain storm, adding to an ice build-up that exceeded the design limits of the wires, the city’s transit commission was told Thursday.
The ice build-up brought two trains to a halt and eventually caused arcing so severe that it melted the copper cable in the train’s overhead catenary system, Director for Engineering Services Richard Holder told the commission.
As the trains’ pantographs, which connect the trains to the OCS, “bumped along over layers of ice,” he said, it caused intermittent power disruptions that triggered faults in the system, bringing those trains to a halt.
“We had eyewitness accounts of arcing in the area and ultimately … the arcing became too serious for the vehicles to continue,” Holder said.
Later, when OC Transpo dispatched rescue trains to tow the stopped trains to the Belfast Road maintenance and storage facility, the arcing became even worse.
“With the slow speed of vehicles trying to move back to the MSF, it resulted in very high-energy arcing that occurred in a very localized section of the contact wire,” Holder said.
“The contact wires basically melted. With the vehicles basically stationery, that arcing all occurred in the main section, generating a huge amount of energy and a huge amount of heat.”
The heavy gauge copper wire has a melting point of 1,000 C and has a breaking strength of 18,000 pounds (816.5 kilograms), Holder said.
It was the most complete and detailed explanation yet of what caused the six-day partial shutdown of the Confederation Line after what seemed to be a fairly ordinary ice storm. In fact, the LRT had withstood more than 50 similar freezing rain events without any problems, Holder said.
The OCS is designed to withstand an ice accretion of 30 millimetres a day and up five millimetres per hour. The Jan. 4 storm approached that threshold, but the unusually warm evening, the high humidity level and the river fog compounded the problem near the Rideau River crossing between Lee and Hurdman stations, he said. No other areas of track were affected by that storm, he said.
It took four days for workers in bucket trucks to physically bash ice off a five-kilometre stretch of the power line. Once that was done, fixing the cable took just a few hours, he said.
The rest of the shutdown included the time it took to thoroughly test the system before reopening it to full service, he said.
To prevent it from happening again, OC Transpo is equipping all its trains with “winter carbons” — attachments that do a better job of scraping ice off the power line. It’s also dedicating staff to monitor the stretch of tracks between Hurdman and uOttawa stations to watch for problems and to more closely monitor the trains’ onboard diagnostics for “signs that the system is struggling,” he said.
It’s also looking at using anti-icing compounds on the OCS when freezing rain is predicted and installing sensors and cameras on the pantographs to detect icing problems. It’s also searching for a non-electric powered vehicle that can be used to tow stuck trains when electrical power on the line is lost.
https://ottawacitizen.com/news/local-new...d-lrt-power-line-after-january-ice-storm
And in today's weather:
Quote:
School buses cancelled Thursday morning: fog advisory over, risk of black ice, freezing rain by afternoon; schools open
Megan Gillis, Ottawa Citizen
Published Feb 09, 2023 • 1 minute read
Freezing rain day just doesn’t have the same ring to it but school buses are cancelled in Ottawa Thursday with a pair of weather alerts in effect.
A freezing rain warning was issued with two to five millimetres of ice expected to build up starting Thursday afternoon and ending Thursday night.
Meanwhile, a dense fog advisory was liftedm as the weather office predicted, by mid-morning.
“Fog is expected to lift late this morning.”
Precipitation may start as snow or ice pellets Thursday afternoon before switching to freezing rain, the weather agency said.
“A prolonged period of freezing rain is expected for the Ottawa River Valley” before it turns to rain overnight, the weather agency said.
“Surfaces such as highways, roads, walkways and parking lots may become icy and slippery. Slow down driving in slippery conditions. Watch for taillights ahead and maintain a safe following distance. Be prepared to adjust your driving with changing road conditions.”
Both the Ottawa Student Transportation Authority and Consortium de transport scolaire d’Ottawa cancelled school buses in the capital due to bad weather.
Schools remain open but it’s up to parents to drop kids off and pick them up at bell time, Ottawa’s English and Catholic boards reminded.
https://ottawacitizen.com/news/local-new...-freezing-rain-by-afternoon-schools-open
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