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Wed December 08 2021

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Dragoncam checks duct quality

14 Aug 14 Running a camera down cable ducts to check quality can save developers and distribution network operators thousands of pounds, a connection company says.

The Dragoncam
The Dragoncam

Dragon Infrastructure Solutions has come up with what it calls the Dragoncam, which is an underground monitoring system to check the inside of cable ducts for ridges and damage. DragonIS says that this removes the risk of having to dig up damaged cable.

Dragoncam illuminates the insides of ducts or channels and records footage as it travels through the system. This can then be analysed by site managers to ensure all ducts have been laid correctly.

The Dragoncam was designed in response to challenges faced on site at Kerriers Solar Farm in Cornwall. DragonIS, which was connecting the site, was asked by the local network engineer to prove that there were no ridges inside the 5.2km of duct that it had just laid. Each section was joined together at 100 metre intervals and on occasion was up to 1.5 metres underground. When such channels are connected incorrectly, small ridges are produced. These can be as much as 12mm thick. This becomes an issue when the electricity cable inside the duct is working at its maximum capacity, because it becomes very hot. When hot it is more likely to become misshapen due to these ridges, which can eventually result in cable failure. Repairing such a cable on a job of this scale could involve a lot of excavation and disruption to the electricity supply.

The length of the channel at the Kerriers site meant that using an ordinary camera system to check for ridges would be expensive. It was estimated that the cost would be more than £12,000 just to live stream from inside the duct and it wouldn’t record every detail. DragonIS’ solution was to build a video camera into a tubular trolley, adding a series of spotlights and wheels, to produce footage from inside the duct. It does not need to be attached to specialist equipment and is simply attached behind a duct brush – equipment used on every site – and winched throughout the entire system. Because it is set on wheels, it is able to travel freely along the channels, recording every join. The spotlights provide enough light to capture its findings before any analysis can occur.

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Project civil engineer Stephen Branch said: “Dragoncam is ingenious. I had no reason to think that there were ridges in the channel of duct which had been laid. But with the channel being so long and deep, I just wanted reassurance. The Dragoncam gave me that - the duct was perfect. It’s a really clever piece of kit.”

DragonIS construction director Tim Pope says: “The Dragoncam was born out of a need to provide a solution to a problem. It will not be needed on every site, but to have this technology available whenever we want is very reassuring.”

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