UK Power Networks Methods of detection current & future Alan - - PowerPoint PPT Presentation
UK Power Networks Methods of detection current & future Alan Croucher ENA 16 th May 2018 So how do we find cable leaks? Currently we have 3 primary leak location methods: Cable Freeze Capenhurst hydraulic method
location methods:
– Cable Freeze – Capenhurst hydraulic method – Perfluorocarbon Tracer Leak Location (PFT)
– Smart Heat – Active pressure control
detection for many years.
by monitoring the pressure drop (or flow) at each end of the circuit, an indication can be given of the leak direction.
– The cable needs to be de-energised – Unable to detect smaller leaks – Multiple excavations required – Disruption to the public and highways – Cost – Time – Leaks can stop when a cable is taken out of service – Cable freezes can lead to future leaks
the flow of fluid through the cable, and by knowing the length and hydraulic resistance of the cable an estimation of the leak position can be found.
– The cable needs to be de-energised – Unable to find smaller leaks – Accuracy of the results – Cannot find multiple leaks on one cable – Again, leaks can stop when a cable is taken out of service
detecting a Perfluorocarbon tracer that evaporates, when it leaks from a suitable tagged leaking cable section at the point of leak.
– The Cable needs to be “tagged” with a PFT, which then needs to reach the point of leak.
method are: – The circuit does not need to be de- energised for the location to be undertaken. – Small leaks are detectable (<40L/m).
This method of tagging only requires that the cable fluid pumped into the circuit to replenish fluid lost to the leak is tagged. The limitation of this method is that it can take some time for the tagged fluid to reach the leak, and the leak to become detectable, for example: If the circuit is leaking 100L per week and is 2km long, and it contains 1000L of “free” fluid, it could potentially take 10 weeks for the cable to be fully tagged
the cable, we heat it
cable, as the fluid moves in the direction of the leak the heat is drawn in that direction.
rate of the cable which needs to be above 400 litres per month to work.
range depending on where the cables are installed.
lowest possible operating pressure (Alarm Pressure)
pressure, leaks may be minimised and less stress put on cable sheaths and joints.