Transmission & distribution | Covered conductor at 52 kV James Varley reports from Öland, southern Sweden
A 52 kV transmission line replacement project currently underway in the southern part of the island of Öland will see E.ON’s first deployment in Sweden of covered conductor in a high voltage application (having previously been used by E.ON predominantly for 20 kV lines).
The covered conductor for the 12 km Öland line is being supplied by Amokabel and the installation contractor is ONE, with completion expected in October.
Why covered conductors? One driver behind the Öland installation, which is in a protected area, is reducing the potential harm to birds and other wildlife arising from bare conductors. The covered conductors are also better able to cope with severe weather and the coastal location.
E.ON will be looking for a significant improvement in line reliability, with the existing, bare conductor, line experiencing no less than six outages in the past year or so. System reliability is of course a key preoccupation for E.ON, and E.ON spokesman Björn Persson notes that even if you are in deep countryside (as the Öland line is) you are entitled to reliable power and increased amounts of it as electrification gathers pace.
The design of the new cable for Öland, builds on Amokabel’s extensive experience worldwide with what it calls “new generation” covered conductor technology.
E.ON press event, Öland
Thanks to its low weight it has proved possible to use the existing poles and cross arms of the Öland line, and installation has proved to be straightforward, as confirmed by ONE, with a team of just three people able to carry out the work on each pole.
The insulation is highly effective but relatively thin, enabling electrical connections to be made using insulation-piercing connectors, able to penetrate the covering and contact the conductors without the need to strip the cable – meaning that making connections is more or less the same as working with bare wire. For Peter Eriksson, CEO of Amo Kraftkabel, the significant thing about the Öland installation is the voltage. Amokabel’s covered cable has been widely perceived to be a medium voltage technology and “I think the market has not been aware that we have products also for high voltage,” he says.
In an ideal world, cables would be placed underground, but this is expensive and not always feasible. Peter notes that covered conductors deliver many of the benefits of undergrounding, but without the exorbitant costs. He also notes that the cost of underground cable increases roughly exponentially with
32 | October 2024|
www.modernpowersystems.com
Installation of 52 kV covered conductor, Öland
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