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Topic Title: Value Engineering - Transformer Windings
Topic Summary: Copper versus Aluminium Transformer windings
Created On: 05 January 2017 05:04 PM
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 05 January 2017 05:04 PM
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KeithB01

Posts: 14
Joined: 24 February 2014

I would like to know what peoples take on transformers windings and what peoples preferences of copper vs aluminium transformer windings been used.

I know what the typical advantages etc. of copper vs aluminium i.e. material losses characteristics, thermal effects, tensile strength, ageing effects, bending flexibility and material sizes etc.

So what i am asking is it a viable value engineering solution to go from a copper wound transformer to an aluminium wound transformer and thus what would be the biggest issue with this?

Would it be the increase in size of the transformer? or the fact that Aluminium transformers are known to have a much reduced life expectancy compared to copper wound transformers or has this issue been much improved with today's technology.

Sorry about the long message.
 05 January 2017 09:20 PM
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Devlinjames

Posts: 14
Joined: 10 December 2014

I have recently purchase 3no transformers and I asked the questions at the time, my main concern was a potential of reduced performance but was advised that the current standard of aluminium wound transformers match that of the copper equivalent. But as with most cases now cost will be the winner.

J Devlin MIET
 06 January 2017 09:26 AM
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KeithB01

Posts: 14
Joined: 24 February 2014

Thanks for that James. I've just been in contact with a transformer company and they have basically confirmed what you stated is generally the case nowadays that aluminium wound transformers have generally caught up in performance and reliability with copper wound transformers. So the only real battle is size vs cost.

So if the space is available then aluminium wound transformers seem to now be the norm according to the transformer company.
 09 January 2017 09:30 AM
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mapj1

Posts: 9679
Joined: 22 July 2004

There are some DNO chaps and at least one system design consultant who regularly read the wiring and regs BB - it may be worth asking there if they have opinion.

-------------------------
regards Mike
 10 January 2017 01:19 PM
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OMS

Posts: 22428
Joined: 23 March 2004

Take a read of this

I will confess to a vested interest here - however, in my experience, aluminium wound liquid transformers rarely outperform the copper wound equivalent and I've seen a number fail in circumstances where I'm sure the copper equivalent would have survived

My experience with aluminium wound cast resin units hasn't ben good either - particularly where the environment is getting harmonic rich

So, personally speaking - unless you are looking for specials, a copper wound unit is smaller and often cheaper as the quantities involved are greater than for aluminium units

If they are "specials" then it's a case of evaluating everything (including keeping one as a spare - copper units tend to be "off the shelf")

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 13 January 2017 05:28 PM
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keithmachell1705

Posts: 62
Joined: 05 April 2004

No issue, except an aluminium (AL) transformer is bigger than copper - so check the spatial planning. This is because of conducting ability. They are simply made to match the CU performance equivalent so you get like for like comparison - which makes them bigger. In fact an AL winding will likely be almost 3 times the size of a CU winding. This does not make the AL transformer 3 times bigger though and an AL is still lighter and cheaper at larger sizes - despite being bigger.

Height is usually the main problem when changing form CU to AL in a predesigned project s the main bulk of increased size occurs here. Often the footprint has enough additional space for the AL - but height is the major increase and is often a less flexible dimension when concept designers used CU alongside architecture sections.

Dissimilar metal connections are easily addressed by ordering the correct glanding plates.

Life is practically no different - negligible in reality and more dependant on the type (ie ANAN, ONAN, ANAF, ONAF etc....). Use k-rated transformers where harmonics are an issue guarantee the right transformer selection.

If you go over 10mVA then AL transformers become less feasible because the secondary windings need to be very fine and AL requires more material and in those finer CSAa, and is very brittle in those smaller fiddly sections.

Your only issues will be client driven, local authority (international projects) or other engineers stigma. AL are cheaper and lighter but bigger. If the DNO are providing don't even bother specifying because they will use what they want.

ABB and Schneider both have a great range. I like ABB. Lead in is usually 4 months - but you need to ask.

Historically there were big issues with AL, but not anymore thanks to regulation.

Don't forget to check the 2015 ecodirective because its all changed:

http://www.energy.siemens.com/...esign-directive_EN.pdf
 16 January 2017 02:57 PM
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OMS

Posts: 22428
Joined: 23 March 2004

LoL - I must still be in the "old and bold" class then - I wouldn't have one over the threshold

OMS

-------------------------
Let the wind blow you, across a big floor.
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