A big blade

heading back from KAIRA to SGO the other morning, I was held up for a considerable period of time at the turn to Meltaus. The reason for this was that a convoy was moving three huge blades of a wind turbine and the first of these was starting to make the turn just as I arrived at that point.

It was quite a long wait as the turn was very difficult given the huge length of the blades. I tried to estimate the length and I suspect they are 40-50 metres long each.

Turning wind turbine blades. (Photo: D. McKay-Bukowski)

Information about the project can be found here: http://www.laatumaa.fi/tuulivoima/joukhaisselka-sodankyla/

New Year's Eve

Well, that's about it for 2013. It has been a hectic, frantic year with lots going on and all sorts of new discoveries and adventures. To all our dedicated readers, thank you for making 2013 our most successful and for all your positive and encouraging comments.

Today at the institute, we had a little celebration for the 100th anniversary of geophysical measurements (more on that tomorrow).

But tonight's "photograph" is a close-up of the inside of an HBA tile, shot at midnight in the depths of a polar night, with no moon, overcast skies and a complete power failure. The temperature outside is -15 (although those tiles keep it at a toasty -10 C inside them).

This photograph is intentionally black.
(Okay... so we made this one up.)

:-)

Thanks for 2013!

Best wishes for the new year!!

Connecting services to the barracks

Following on from the previous posting, once the barracks were in place, the services needed to be connected to it. An agricultural-drain was used to make a duct between the RF-container and the barracks. This will carry power, network, grounding and probably some other cables as well. The following photograph was taken during the end of last summer.

The cables need to be buried, not just for protection against the snow, but also vehicles and any animals that might otherwise damage it. Although the barracks is movable and remains on its wheels, it is semi-permanently connected (like a long-term holiday caravan!).

Grounded

The second ground connection has been made on the electrical supply to the site. This was done at the beginning of the month, prior to the connection of the main electrical connection.

Although we have had mains power on the site for some time, the high-capacity circuit to the RF-container had not yet been made.

Additional works and checks need to be carried out before that can be done.

Power point presentation

Within the RF-container there is a power switchboard which brings in the electricity supply. Although the power line itself has been brought as far as the site, we have not yet connected it to the RF-container and the container electronics.

However, the next step in this work has now been completed, with the external cable being connected to the switch box inside the container.

In the photograph, Marko Kauranen explains the work that has been done.

Power poles

The main power line to the KAIRA site has now been completed and has been energised. This brings the mains across to the south edge of the HBA field. It is done using tall timber poles to avoid too much disruption to the native ground cover and to make maintenance and deployment easier.

At this point there is the final power pole, and a connection down to a termination box. From there the cable needs to go underground for the rest of the way to the central site power point (which is located in the RF-container). The underground cable has been buried in, but it has not yet been connected, as the termination at the RF-container end has not yet been installed.



Because of the sensitivity of the array, it is essential that the electrical power line be kept out of the way on the final approach to the site. This is not just because it carries power, but because it is a long metal object. This reflects radio waves, which can cause confusion in the final images.

The same applies to other metal objects. They have to be kept away from the array as much as possible to minimise these reflections.

Even the reflections of astronomical radio sources (such as Cas A, Cyg A, etc.) can cause spurious images ('ghosting') to appear in the data.

Power pole route

While all the levelling work and surveying and all the other things have been going on at the main mound, from further south, there has been another KAIRA-related operation under way.

Electrical power to the site needs to come in from somewhere, and that place happens to be a power termination point about a quarter of a mile or so to the south of the HBA field.

During the week, the electrical contractors have been moving through the dense Arctic undergrowth, which at this time of the year is very thick, due to the vigorous summer vegetation growth. (How the team put up with the mosquitoes down there, I have no idea!)

To do this, they have used a combination of machinery, ranging from winches to drilles to tractors to off-road 'quad-bikes'.

The first step has been to mark out the route and deliver the poles to the area. Then each one is dug into the ground. Additional stabilisers are also provided to ensure that they do not fall (especially as Arctic ground is prone to huge shifts due to the freezing/thawing cycles).

Hopefully we will power to the site very soon!

Cable reel

We've another photo that we forgot to include in our article the other day about the delivery of the power cable equipment. This is the cable reel, fully mounted on the spool sled, ready for running out.

The cable from the nearest supply will need to run out over ground at first, before finally being buried in for the last short stretch near the antennas. This is actually a tricky business, as the cables need to be protected from ground freezing and all the problems that can bring with it.

In fact, even the above ground poles will require some special precautions. It is a common site to see leaning or collapsed power lines in the Arctic due to the soil movement at the permafrost interface.

Power kit

On Tuesday the first delivery for the installation of electrical power arrived at the site. Unlike other LOFAR sites, we do not have electrical power readily to hand, and we will need to deploy power poles to get the cable from the nearest transformer all the way up to the site. In the first photo, the cradle is being unloaded from the transporter. The reel (already on the ground) will sit on this and the cable can then be spooled out over the difficult terrain.


The cable is not copper, but is actually aluminium. This has the advantage of being very light.

Because of the permafrost, burying cable is not an option. Thus, for the parts where it is not directly on site, the power will be suspended from timber poles.

In the above photograph some of the poles are being unloaded at the site. More will be posted on the power once the deployment work gets under way.