# Xmer core made of wood?



## rg1 (Oct 1, 2017)

Q- If Xmer core were made from wood having same ratings as an iron cored.

1. Not possible technically

2. The  Xmer size will be very large compared to that of Iron cored

3. The size will be same as that of Iron core

4. Size will be smaller than Iron cored.

Give your answers with reasoning


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## Pixie (Oct 2, 2017)

The size would be bigger compared to iron core for same rating. 

Thanks!


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## rg1 (Oct 3, 2017)

Pixie said:


> The size would be bigger compared to iron core for same rating.
> 
> Thanks!


Yes @Pixie the size of wooden core  Xmer will be bigger than Iron cored for same ratings. Why?  and how big? Let me try to get it like this.

For a particular rating of Xmer there will be a particular amount of flux flowing in the core of that transformer. Say the amount of flux be x Wb. As the reluctance to flux ( Equivalent of resistance in electrical ckts) offered by wood is approximately of the order of  2500 times the reluctance offered by iron, the area of the  wooden core has to be  2500 times that of iron core for getting the same flux of x Wb by same mmf ( equivalent of emf in electrical ckts).  

The size of wooden core can now be imagined. A 1cmX1cm core of iron will be equivalent to  50cmX50cm core of wood.

We only talked of one dimension of the problem here - only Core.


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## GaryD (Oct 4, 2017)

rg1 said:


> Yes @Pixie the size of wooden core  Xmer will be bigger than Iron cored for same ratings. Why?  and how big? Let me try to get it like this.
> 
> For a particular rating of Xmer there will be a particular amount of flux flowing in the core of that transformer. Say the amount of flux be x Wb. As the reluctance to flux ( Equivalent of resistance in electrical ckts) offered by wood is approximately of the order of  2500 times the reluctance offered by iron, the area of the  wooden core has to be  2500 times that of iron core for getting the same flux of x Wb by same mmf ( equivalent of emf in electrical ckts).
> 
> ...


Does wet wood / dry wood matter?


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## P-E (Oct 4, 2017)

Wood matters.


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## rg1 (Oct 4, 2017)

GaryD said:


> Does wet wood / dry wood matter?


It does not matter, reluctance to flux of both water and wood are same. Even copper core will have same size as wood. This is Reluctance to flux . Only magnetic materials like iron offers less reluctance; all others offer high reluctance.


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## rg1 (Oct 4, 2017)

rg1 said:


> It does not matter, reluctance to flux of both water and wood are same. Even copper core will have same size as wood. This is Reluctance to flux . Only magnetic materials like iron offers less reluctance; all others offer high reluctance.


I think you are thinking about electrical resistance. Yes water (impure) is better conductor of electricity, so wet wood becomes a better conductor of electricity but as far as magnetic ckt is concerned, both wood and water behave same. I will now give one spin to tickle your brain- Good heat conductors are mostly good electricity conductors but this similarity is almost lost with magnetic ckts.


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## cupojoe PE PMP (Oct 4, 2017)

I'm going to say not technically or commercially possible. Refer to table 2.1 at http://www.tcforensic.com.au/docs/article10.html

Assuming you could make it work, with similar efficiency as steel, you would expect a dry type transformer to have a 150 deg C rise. I suspect wood would (hehe) be higher. Wood will slowly char at 120-150 deg C.

The wood would only be possible in air. It would soak up the oil and turn to mush. It will eventually rot in air as well. So not commercially viable even at small ratings. At large ratings, air cooling is going to be a huge problem, so again not technically possible.

Further, there is so much water content within the wood, that I suspect it could create a high-impedance connection between primary and secondary.


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## cupojoe PE PMP (Oct 4, 2017)

rg1 said:


> I think you are thinking about electrical resistance. Yes water (impure) is better conductor of electricity, so wet wood becomes a better conductor of electricity but as far as magnetic ckt is concerned, both wood and water behave same. I will now give one spin to tickle your brain- Good heat conductors are mostly good electricity conductors but this similarity is almost lost with magnetic ckts.


But the wet cells will conduct electricity between primary and secondary sides. So you will have an electrical connection, which will be a problem.


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## rg1 (Oct 4, 2017)

cupojoe PE PMP said:


> But the wet cells will conduct electricity between primary and secondary sides. So you will have an electrical connection, which will be a problem. The insulation is separate issue. But core is not meant for insulation, it is meant for carrying flux, why it should conduct electricity between Primary and secondary.


Lol. Becoming interesting. That is the reason I mentioned initially that we are discussing one dimension of the issue- Only flux. There are other dimensions to the issue- economy, Operating Temperatures, cooling, cooling medium, life, eddy currents, Insulation and many more.


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## cupojoe PE PMP (Oct 20, 2017)

Unless you consider all dimensions of a product, you will never know if it is viable.


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## rg1 (Oct 20, 2017)

cupojoe PE PMP said:


> Unless you consider all dimensions of a product, you will never know if it is viable.


You are more right sir.


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