Contractors dug the trench and laid the concrete bedding for the power cables over the last couple of months. My previous post illustrates the map and location of the first joint hole, 900m from the McFadden Zone substation.
Having not witnessed the laying of a really heavy power cable before, this was a particularly exciting time for me. Rollers were laid in the trenches and on the corners with cable layers at intervals to assist the passage of the cable. Conduit was installed in sections and guides inserted into the entries of the conduit.
|Rollers with the nylon pulling cable in place for the first cable.|
|Corner rollers with conduit protective entry|
A nylon cable was used to pull the cable and was attached using a cable puller and drawn by a torque-controlled winch set to 7 Newton-metres strain.
The giant cable drum was mounted on a roller machine with nylon bearings and a makeshift braking system using an 8x4 block of wood.
|Me in front of the giant cable drum (with full PPE, of course!)|
|The drum on it's own|
|The cable specs on the drum|
|The drum 'jack' specifications.|
|I'm 90% sure (!) this is a nylon bearing.|
|The 7-ton breakaway swivel (the black bit).|
It seems that, as with a lot of trades, a successful objective can only be achieved with excellent preparation. Everything from placement of rollers to conduit placement and cable lubrication, if done properly, should (being the key word!) lead to a successful outcome. Teamwork and good radio communication is paramount.
So the pull begins. A team of around 6 'follow' the cable down the run, after a an initial 'take up the slack' and check all is running correctly.
|The start of the cable run|
|The nylon drawcable wearing on the conduit insert|
Video: the winch
Video: the cable running
Video: Lubricating the cable
Lubrication is essential for the cable as it goes around corners in conduit to ensure the cable is not damaged and also the conduit is not compromised by the friction of the cable.
|The lubricating medium.. goop!|
|Nearly finished.. comms cables to go in..|
The cables are being laid on top of reinforced concrete (in places) and encased in a flowable thermal backfill (a weak concrete) with a red coloured top layer.
The next step is jointing. I'm not sure if I will be able to cover that process, but I did see some terminating at the McFaddens zone substation.. see below:
Sean Baker and Barry Kelly are Cable-Jointing gurus, both ex-UK and supreme at the trade. Their workmanship is second-to-none, and they are effectively the engineering equivalent of surgeons, precision work being their game.
The first time I saw them was doing the final terminations for the 66kV temporary overhead line circuit at the Dallington zone substation in April 2011.
|Sean doing 66kV terminations|
|The beginnings of a SERIOUS lead wipe..|
|The finished product|
The second time I saw them was jointing a damaged 66kV oil-filled cable on Armagh St in the Christchurch city 'Red Zone' in May 2011.
|Oil-filled Cable Jointing|
|Barry polishing the XLPE insulation|
|The pole under construction|
|The kit comes together. Shaun and Barry have workhands to assist.|
|The cables to be joined|
|Perfectionists; Barry keeps his tools in perfect order and condition while working.|
|Now THAT is a lead wipe..!|
|The finished product|
I'd like to thank Shaun and Barry. They're so passionate about their trade, and have been more than happy to share their trade with me. Nice guys, and great role models.