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Anonymous Poster #1

Transformer Problem

09/27/2017 10:44 PM

Dear Sirs,

If one has to verify if the transformer given (single phase, 150 kVA, 33/0.4 kV) is aluminum or copper winding transformer - how to find and test? Does the insulation value differ?

Regards,

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#1

Re: Transformer problem.

09/27/2017 11:00 PM

One contacts the maker of the transformer and asks them.

Aluminum wires will be 1 1/2 times larger but insulation class should be the same in either case.

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#2

Re: Transformer problem.

09/27/2017 11:06 PM

Check datasheet, discuss with manufacturer or open transformer and inspect (following proper procedures to ensure the transformer and its oil are not damaged), likely in that order.

Why do you ask? Is this for material recycling and recovery?

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Guru

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#3

Re: Transformer Problem

09/28/2017 8:38 AM

If its for recycling beware of copper clad aluminum wound transformers. They are not worth anything at all. Many a scrap man has been financially burned by them.

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#4

Re: Transformer Problem

09/28/2017 9:18 AM

Assuming that it is properly designed (lowest price for a given output power)

  1. Checking the colour would be the easiest, but I guess you do not have access to it.
  2. Compare winding size to core size. Copper winding is smaller.
  3. Compare weight and volume. Copper transformers have higher density.

Insulation value depends mostly on ambient humidity, so it will give you no information about the material.

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#5

Re: Transformer Problem

09/28/2017 12:02 PM

You could taste the wires? Be careful, though! If not blind, the copper ones will be a reddish-orange colored metal, and the aluminum will appear more silvery white.

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Guru

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#6

Re: Transformer Problem

09/29/2017 1:05 AM

Come on guys! This is an engineering site and these guys are playing with you!!!

If it's a modern transformer and you're in the US, most likely the windings are aluminum. The rest of the world uses copper.

If it's an older transformer and you're in the US, it may have copper windings.

The best way to check is to pull the model number and check with the manufacturer.

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#7
In reply to #6

Re: Transformer Problem

09/29/2017 1:51 AM

In Russia uses aluminum too. No load losses (W) of aluminum is greater than that of copper. Compare with the famous transformer.

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#8
In reply to #7

Re: Transformer Problem

09/29/2017 1:58 AM

Aluminum is cheaper to use and weighs less. Aluminum also oxidizes into an insulator, where copper oxidizes into a conductor. So aluminum could become a problem if the contacts become oxidized. Production is typically very good and any failures occur soon after installation, so it's not a problem until someone does repair work and they don't protect the aluminum from oxidation.

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#9
In reply to #8

Re: Transformer Problem

09/29/2017 2:55 AM

Yes, I totally agree with you. I want to add that coils of transformer are install in a tank of oil, usually. Consequently, oxygen can not damage it.

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#10
In reply to #9

Re: Transformer Problem

09/29/2017 3:16 AM

Here in the US, I believe all smaller - 150 KVA is considered smaller - are "dry" transformers. Big transformers are oil cooled.

Years and years ago, a really good friend of mine heard a loud explosion. He drove to the site and it was in the power substation. One of the transformers exploded and there were two kids inside who I believe were killed.

Here's what I heard. Two kids were on acid and they jumped the fence and went into the power substation. They sat on one of the transformers and they must've done something. The transformer blew up and the kids were burned really badly. My friend saw one of the kids up against the fence screaming and burnt. He jumped the fence to help and he told me when he touched him, his skin came off. The other kid was on the ground not moving. My friend told me the kids had a bad trip due to bad acid. We know the person who sold the acid - I'm not sure if he got caught.

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#11
In reply to #10

Re: Transformer Problem

09/29/2017 4:19 AM

This story are very horrible. This is possible, unfortunately. When I do project substation I install an overheat protection of transformer... And the locks on the doors.

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#12
In reply to #11

Re: Transformer Problem

09/29/2017 9:54 AM

Please elaborate more on the overhead protection of the XFMR?

Around here, we have high voltage switch gear that if you touch any live part, you basically turn into a cinder.

What can you tell us about "woodpecker" project without getting into trouble?

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#13
In reply to #12

Re: Transformer Problem

09/29/2017 5:39 PM

Overheat protection of XFMR:

- Dry transformers. In coils of transformer installed a thermocouples. The thermocouples connected to Transformer Temperature Controller . If the temperature exceeds the set value, then Transformer Temperature Controller it will give a signal to relay protections of transformer. And relay protections (Siprotec-4) will disconnect the switch.

- Sealed transformer. These transformers are most common in Russia. In a tank of the transformer installed a pressure relay .When the oil inside the transformer tank is heated, the oil pressure increases and the relay sends a signal to relay protection for disconnect a switch.

- oil transformer with conservator. It is the old transformer or high power. Buchholz Relay.

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#16
In reply to #13

Re: Transformer Problem

10/02/2017 9:01 AM

First of all my bad eye sight interpreted "overheat protection" as overhead protection, LOL. This is even after getting eyes checked and new glasses.

The Buckholz relay bit is interesting. Thanks, I learned something new today. Electrolytic failure in XFMR leads to gas production, which drops the float ball in the relay, trips the XFMR. Good.

Power distribution is not my wheelhouse.

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#14
In reply to #12

Re: Transformer Problem

09/29/2017 6:04 PM

"Woodpecker" project... Sorry but I don't know about it nothing. What is it?

In Russia all the switchgear closed. The key have Service Company. HV switchyardas as rule protected.

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#17
In reply to #14

Re: Transformer Problem

10/02/2017 9:05 AM

Apparently, "Woodpecker" aptly named by American Military due to the 10 Hz repetition rate of pulsated radar from this large array antennae near Chernobyl in Ukraine.

The site is apparently abandoned now, but it appears Russia has made another "Woodpecker" somewhere and is "pinging the world" once again, seemingly having something to do with mind control. Apparently, someone in Russia thinks it nice to get inside people's heads and have a picnic there. I am afraid of what my mind could unleash on Russia, a new form of lunch meat or something...

It does seem to be telling me to go outside and smoke now, but no national anthem repeating in my mind this time.

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#15
In reply to #12

Re: Transformer Problem

10/02/2017 7:45 AM

Well, according to Wikipedia, the Duga radar can make changes in weather.

It would be great if it could stop climate change!

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#18

Re: Transformer Problem

10/06/2017 1:02 PM

If you have technical data sheet of same rating of trafo of copper winding and if you measure accurately the winding resistance of aluminium winding trafo , value of the later will be higher.

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#19
In reply to #18

Re: Transformer Problem

10/08/2017 3:05 PM

Theoretically yes, but only if you have the same diameter wire. I've seen thicker wire used for al vs cu - for the same power rating transformer. I believe the resistance should be close, since the thicker al wire compensates for the higher resistance in the material.

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