A recent article in the IEEE Spectrum, highlighted the fact that Power Grid Capacity could be "doubled" by using a new HV cable construction called ACCC.
It mentioned that some of the most fastest deployment of this new cable is occurring in India.
Has anyone in the UK evaluated this new cable design for possible reconductoring of existing lines?
Peter Brooks
Palm Bay Florida USA
I think we've traditionally used steel cored aluminium for transmission lines, but this seems to be slightly different - https://en.wikipedia.org/wiki/ACCC_conductor
Despite the headlines, on a like-for-like basis the cable only seems to be able to carry 14% more current than a conventional conductor - the higher rating coming from running at a higher temperature and so incurring much higher losses - so perhaps handy for emergency situations but not ideal for general use. It also seems to have some new disadvantages, e.g.increased sag under ice loading, which could be more of an issue in much of the UK than in more equatorial regions.
- Andy.
Hello Andy:
This picture attached to the IEEE article shows the reconductoring of HV lines in Arizona, which can get get pretty cold at certain locations like Flagstaff or Tucson, not so must in Phoenix, where I used to live
Apparently the aluminum connector is "Annealed aluminium" which results in small pie shaped blocks instead of round wire with air gaps.
It is not clear to me if they put additives into the Aluminium during the annealing process.
At one point in my technical education I had to melt Aluminium and pour it into molds to make screwdriver handles. These handles were pretty hard.
Peter Brooks
From what I remember from school metalwork, annealing is usually just heating and cooling (I remember heating copper until it was red hot and then quenching it after it was 'work hardened' by hammering - but I think some other metals are usually slow cooled). Certainly aluminium can be fairly flexible - in the 1970s we used it instead of copper in domestic cables (bad move, but that's another story).
- Andy..
Hello Andy:
I also used to harden soft iron using case hardening (powder) with rapid quenching in a cold water bath, which produced a large bang.
By the way my current house was built during the worldwide copper shortage in 1970. It uses copper wire for the high current circuits and aluminium for the low current (lighting) circuits.
When I replace the switches or sockets in my house I have to use special CU/AL designed replacements or a special solution.
Peter Brooks
.
By the way my current house was built during the worldwide copper shortage in 1970. It uses copper wire for the high current circuits and aluminium for the low current (lighting) circuits.
Isn't that the wrong way round, compared with the current codes?
The problems in the UK seem to come from the smallest cables. At least with the big ones, you can put proper crimps on the ends. BT used aluminium at one point for phone lines, and are now regretting it.
Hello Simon:
The original problem with using Aluminum wire in the house wiring, was oxidation resulting in high resistances in the main fuse box and house fires, years later.
I was forced to change out my main fuse box by the insurance company. The internal fuse box connections have to be, (if I remember correctly) Cadmium Copper!
Peter Brooks
Isn't that the wrong way round, compared with the current codes?
Indeed, but I can see the thinking perhaps - aluminium is a poorer conductor than copper so if a cable is carrying close to its capacity the aluminium would have to be a size or two larger - whereas lighting circuits are typically underloaded, so you could stick with something closer to the original size and so side step all sorts of problems with terminals, cable entries, etc being too small. In the UK aluminium was used for just about all domestic cable sizes.
- Andy.
Hello Simon:
Just reread this message and noticed the word "crimping" cable ends.
Over here in the US, crimping of wires is usually only seen in electric ovens subjected to heat. I haven't yet looked to see if it also used in my new refrigerator.
Wires are joined together using threaded twist caps. They come in a whole range of sizes and work for both solid and stranded wire.
When joining Aluminium to Aluminium or Aluminium to Copper I use a material made by Ideal Industries "NOALOX" anti-oxidant joint compound. They have a UK address (Warrington Cheshire WA5 5TN)
Peter Brooks
Palm Bay
small - less than 25mm2 alu cables have been deprecated here since the mid 1970s, and the ones that were in domestic use were aluminium with a copper flash coating that meant they were OK with brass and copper fittings, or at least that was the idea. Actually the copper coat tends to fail, so they very quickly changed from the next 'great thing', to 'not a good idea at all', and there is mercifully little of it left in service.
The big stuff is very much used especially for long sub-mains, both above and below ground, in the 100mm2 and up sort of scale, and there there are special aluminium crimps that allow alu-alu joints without any mixed metal at all. They are reassuringly expensive and still fail occasionally.
M.
edited for typo
Regard the use of "special taps" to connect LV Aluminium cables, that down feed power, from the pole transformer to my house.
A few years ago I had a power tap that became loose and ended up supplying 220 v to my 110 v lighting lines
blew computers and TV's.
We get some very strong winds from time to time which end up moving the external AC power lines back and forth
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