Power Transformers

T

tony.r

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Power Transformers

Could anyone tell me what the lines per square inch is on M6 silicon steel.
I need to re-calculate primary and secondary windings for my power trans.

thanks
tony.r

http://www.ncable.com.au/~tony.r/Transformer_Page.html
 
On Tue, 23 Sep 2003 12:27:07 GMT, "tony.r" <tony.r@ncable.com.au>
wrote:

Power Transformers

Could anyone tell me what the lines per square inch is on M6 silicon steel.
I need to re-calculate primary and secondary windings for my power trans.

thanks
tony.r

http://www.ncable.com.au/~tony.r/Transformer_Page.html


Hello Tony,
Click to expand...
I had a look at your web site but I am still a little confused.
What went wrong with the transformer originally?

You say also that you rewound the transformer and it works
but gets too hot. I assume that you rewound it with the same
number of turns and wire gauge as was there before.

Assuming 240V input, If your transformer was at my place,
I would connect the transformer primary up to my variac
and slowly increase the voltage applied and also monitor
the primary current. If the current stays in the 10s of milliamps
region with 240 V applied. I would be pretty happy and
then carry on with load testing the secondary.

Tony, with unloaded secondary windings. How much
primary current does your rewound transformer draw
with 240 Volts applied. (assuming its meant for 240V use)

Regards,
John Crighton
Hornsby
 
Hi John

At the maximum the amp should draw no more than 1 Amp.
At idle I am not sure ?
The primary did have a fault (short) and the blown fuse and low resistance
reading showed that.

1000 Primary windings of 0.25 mm Enam/Copper wire is obviously to few
windings and the gauge of wire could be heavier to reduce losses and heat.

tony.r
http://www.ncable.com.au/~tony.r/
 
On Wed, 24 Sep 2003 09:16:37 GMT, "tony.r" <tony.r@ncable.com.au>
wrote:

Hello Tony
At the maximum the amp should draw no more than 1 Amp.
At idle I am not sure ?
Click to expand...
If this idling current or magnetising current is high, then your
transformer will get hot just sitting there with no secondary loads.
Measure the primary idling current and tell us what it is.


The primary did have a fault (short) and the blown fuse and low resistance
reading showed that.
Click to expand...
OK


1000 Primary windings of 0.25 mm Enam/Copper wire is obviously to few
windings and the gauge of wire could be heavier to reduce losses and heat.
Click to expand...
Was the 1000 turns accurately counted from the old winding, no
guesses?

When you use a variac on the input and slowly turn up the applied
voltage, you can see the primary current rise almost proportionally.
When the primary current starts to rise fast with just a small
increase in the applied volts then you know there are not enough
turns for that particular applied voltage.

Borrow a variac and have a bit of play, you will see what I am
going on about. Heh heh heh.....

tony.r
http://www.ncable.com.au/~tony.r/
Click to expand...
Regards,
John Crighton
Hornsby
 
"John Crighton" <john_c@tpg.com.au>


When you use a variac on the input and slowly turn up the applied
voltage, you can see the primary current rise almost proportionally.
Click to expand...

** For an E-I tranny - yes. But not a for a toroidal.

Those buggers show SFA primary current until the saturation limit is
reached, then all hell breaks loose !



When the primary current starts to rise fast with just a small
increase in the applied volts then you know there are not enough
turns for that particular applied voltage.
Click to expand...

** Well, ....... maybe.

Some mains txfmr designers like to stear well clear of saturation while
others love to WALLOW in it !!!!

The only real physical limit is * HEAT * - ie how many I squared Rs are
there ??

As long as that number is not more than 5% or 10 % of the rated VA all is
"cool" as far as being a useable design is concerned.


Borrow a variac and have a bit of play, you will see what I am
going on about. Heh heh heh.....
Click to expand...

** Maniacal laughter from a transformer designer is a WORRY !

He'll be visiting graveyards for spare parts soon .........




............ Phil
 
On Wed, 24 Sep 2003 22:24:32 +1000, "Phil Allison"
<philallison@optusnet.com.au> wrote:

"John Crighton" <john_c@tpg.com.au


When you use a variac on the input and slowly turn up the applied
voltage, you can see the primary current rise almost proportionally.


** For an E-I tranny - yes. But not a for a toroidal.

Those buggers show SFA primary current until the saturation limit is
reached, then all hell breaks loose !



When the primary current starts to rise fast with just a small
increase in the applied volts then you know there are not enough
turns for that particular applied voltage.


** Well, ....... maybe.

Some mains txfmr designers like to stear well clear of saturation while
others love to WALLOW in it !!!!

The only real physical limit is * HEAT * - ie how many I squared Rs are
there ??

As long as that number is not more than 5% or 10 % of the rated VA all is
"cool" as far as being a useable design is concerned.


Borrow a variac and have a bit of play, you will see what I am
going on about. Heh heh heh.....


** Maniacal laughter from a transformer designer is a WORRY !

He'll be visiting graveyards for spare parts soon .........




........... Phil
Click to expand...
Hello Phil,
Good, I am glad you are here, I was wondering why you
hadn't jumped in sooner to help Tony out with his transformer.

From the pictures at the web site I thought I saw a bunch
of E & I laminations. Tony will put us straight as to what
he has got. Anyway, I would still like to know what the
idling current is when Tony gets round to measuring it.

Over to you Phil, to sort Tony's transformer out. Heh heh heh
It is getting late, I will see your words on my screen tomorrow.
Regards,
John Crighton
Hornsby
 
Hi Phil , John

Yes it the old wasteless "E" and "I" Laminations and these examples came
from the troublesome trans.

When I rebuild it I will run some more detailed tests.

M6 G.O.S.S How many Lines per Square Inch ?

4.5 volts per turn gives me 1080 pri and 855 sec turns
but what is the lines per Sq inch ?

tony.r
http://www.ncable.com.au/~tony.r/
 
"tony.r" <tony.r@ncable.com.au


4.5 volts per turn gives me 1080 pri and 855 sec turns
but what is the lines per Sq inch ?
Click to expand...


** Ask a question that makes sense.



.......... Phil
 
O.K School master Phil !!!

M6 Grain Oriented Silicon Steel

What is the max. flux density for this material ?

A coefficient in lines per square inch would be acceptable.

tony.r
Student
 
"tony.r" <tony.r@ncable.com.au> wrote in message
news:3f71c0bd$1@news.comindico.com.au...
O.K School master Phil !!!

M6 Grain Oriented Silicon Steel

What is the max. flux density for this material ?

A coefficient in lines per square inch would be acceptable.
Click to expand...


** Go ask a transformer lam supplier - I am not one.




........... Phil
 
Ha Ha

I have actually, smartass. Hammond are getting back to me.

It will be easier to build a new bugger from the start and with the correct
silicon steels and tec specs to calculate windings correctly.

Or I could try the yanks on A.G.A would not get me far though before it
turned into a slinging match.

Every little point is debated.

tony.r
Looney bin time


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"tony.r" <tony.r@ncable.com.au> wrote in message
news:3f7246ea@news.comindico.com.au...
Ha Ha

I have actually, smartass. Hammond are getting back to me.

It will be easier to build a new bugger from the start and with the
correct
silicon steels and tec specs to calculate windings correctly.
Click to expand...

** That is a load of bull.

It is not simply a matter of "calculating" the correct turns per volt or
saturation point - you need to do tests on the actual core stack and
measure the magnetising current as the primary voltage increases. Then
allow that the load on the secondary side actually pulls the core OUT of
saturation when in use due to primary voltage drop.

A 300 VA tranny on 240 volts AC may have as much as 1 amp off load
magnetising current and be fine.





............. Phil
 
On Thu, 25 Sep 2003 10:59:24 +1000, "Phil Allison"
<philallison@optusnet.com.au> wrote:

"tony.r" <tony.r@ncable.com.au> wrote in message
news:3f71c0bd$1@news.comindico.com.au...
O.K School master Phil !!!

M6 Grain Oriented Silicon Steel

What is the max. flux density for this material ?

A coefficient in lines per square inch would be acceptable.



** Go ask a transformer lam supplier - I am not one.




.......... Phil


Morning Gents,
Click to expand...
Tony, here is the phone number of my local transformer Guru,
John Cox of Magcom, 2/17 King Rd, Hornsby 02/94762723.
This man is very helpful. He will tell you all about the different
grades of laminations and their different flux densities.

He might even mention his bible.
Design Shortcuts and Procedures for Electronics by Ordean Kiltie
ISBN 0 916 512 274.

Out of that book, John Cox gave me this formula . You may
like to compare it with your own books just for interest.

Flux density in KG (Kilo Gauss) = 70 times V divide by A times T

where
A = area in square inches
V = volts
T = turns

John Cox told me,
using a flux density 10 to 13 Kilo Gauss is acceptable.
Over 14 KG is too high.
If using cheap lamination material use a figure of 10 KG
If using top quality lamination material use a figure of 13 KG

Ring up John Cox, he will point you in the right direction.

Regards,
John Crighton
Hornsby
 
Phil Allison wrote:

"tony.r" <tony.r@ncable.com.au> wrote in message
news:3f71c0bd$1@news.comindico.com.au...


O.K School master Phil !!!

M6 Grain Oriented Silicon Steel

What is the max. flux density for this material ?

A coefficient in lines per square inch would be acceptable.





** Go ask a transformer lam supplier - I am not one.




.......... Phil




Phil you have an attitude problem....get a life...the world is not one
Click to expand...
big transformer.......or is it?
Dave
 
"D.Castles" <d.castles@latrobe.edu.au>

Phil you have an attitude problem....get a life...the world is not one big transformer.......or is it?

Dave


** My gawd !!!

Dave Castles is back from the dead - and still fooling them he is a tech down at Latrobe Uni.

As usual, he is unable to comprehend a single, simple idea re transformers - or anything else.





.............. Phil
 
Thanks John

I am moving in the right direction now thanks.

tony.r
http://www.ncable.com.au/~tony.r/


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"tony.r" <tony.r@ncable.com.au> wrote in message
news:3f72f529$1@news.comindico.com.au...
Thanks John

I am moving in the right direction now thanks.
Click to expand...


** Says a blind man about to step off a cliff ........




............. Phil
 
Hammond Electronics Pty Ltd

The lamination in the 369EX is a 26 gauge, non grain oriented silicon
steel. The nominal flux density at 50 Hz ( worst case ) is 15,200 gauss or
98.07 lines per inch. This steel was chosen due to the fact that power
transformers for audio applications have lower flux density's to avoid stray
field and in turn yield lower core losses. Also distortion is less critical
for power supply applications. We do use 29 gauge grain oriented silicon
steel laminations for all of our output transformers where distortion is
critical.

I hope this helps you. If not , please contact me.

Doug Hutt
Hammond Engineering
dhutt@hammondtron.com

Hi

I would like to know what type of silicon steel was used to make the 369EX
and what the specs of that steel is.
Lines per square inch / G.O.S.S

Thanks
tony.r
http://www.ncable.com.au/~tony.r/




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Blind Bart and the white canes.

Now that I have the specs from the manufacturer it was just a matter of
running it through the formula.

The final turns per volt proved the point.
The original heater wind was 35 turns and my calculations came to 34.818 .

I have rewound the trans and will test it tomorrow.

Thanks for all your help Aus.Electronics.

tony.r
Blind...


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