transformer thermals...

[server]

On Wednesday, August 5, 2020 at 7:38:00 PM UTC-4, John Larkin wrote:

On Wed, 5 Aug 2020 23:32:02 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

I think people design transformers for
equal copper loss in the primary and secondary

BTW, what is the source of this and similar rules of thumb (e.g. equal
copper and core losses)? Logic says that one should always design for
minimal total losses, given the economic constraints.

Best regards, Piotr

I don\'t think transformers are usually designed for equal core and
copper losses. This one runs cold at full AC voltage but no load.

They are designed for equal primary and secondary copper losses at
full load, I think.

Cooling depends on surface area. You get more surface area by adding
more copper, and that relationship is not linear (the volume-surface
thing, like mice and elephants) so core loss might require a lot of
expensive copper.

I\'m intrigued by the matrix transformer concept: two transformers
with primaries in series and secondaries in parallel have both 1/4th
the i^2*r losses each, and more dissipation surface per watt compared
to a single giant lump of copper buried in steel.

Cheers,
James

 

[Phil Hobbs]

On 2020-08-07 09:59, dagmargoodboat@yahoo.com wrote:

On Wednesday, August 5, 2020 at 7:38:00 PM UTC-4, John Larkin wrote:
On Wed, 5 Aug 2020 23:32:02 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

I think people design transformers for
equal copper loss in the primary and secondary

BTW, what is the source of this and similar rules of thumb (e.g. equal
copper and core losses)? Logic says that one should always design for
minimal total losses, given the economic constraints.

Best regards, Piotr

I don\'t think transformers are usually designed for equal core and
copper losses. This one runs cold at full AC voltage but no load.

They are designed for equal primary and secondary copper losses at
full load, I think.

Cooling depends on surface area. You get more surface area by adding
more copper, and that relationship is not linear (the volume-surface
thing, like mice and elephants) so core loss might require a lot of
expensive copper.

I\'m intrigued by the matrix transformer concept: two transformers
with primaries in series and secondaries in parallel have both 1/4th
the i^2*r losses each, and more dissipation surface per watt compared
to a single giant lump of copper buried in steel.

Cheers,
James

You\'d probably gain more than that on the primary at least (especially
at 240V) because less of the volume would be used up by the
insulation--you\'d have more than twice the copper cross-section and the
volts per turn would be the same.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[server]

On Fri, 7 Aug 2020 06:59:00 -0700 (PDT), dagmargoodboat@yahoo.com
wrote:

On Wednesday, August 5, 2020 at 7:38:00 PM UTC-4, John Larkin wrote:
On Wed, 5 Aug 2020 23:32:02 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

I think people design transformers for
equal copper loss in the primary and secondary

BTW, what is the source of this and similar rules of thumb (e.g. equal
copper and core losses)? Logic says that one should always design for
minimal total losses, given the economic constraints.

Best regards, Piotr

I don\'t think transformers are usually designed for equal core and
copper losses. This one runs cold at full AC voltage but no load.

They are designed for equal primary and secondary copper losses at
full load, I think.

Cooling depends on surface area. You get more surface area by adding
more copper, and that relationship is not linear (the volume-surface
thing, like mice and elephants) so core loss might require a lot of
expensive copper.

I\'m intrigued by the matrix transformer concept: two transformers
with primaries in series and secondaries in parallel have both 1/4th
the i^2*r losses each, and more dissipation surface per watt compared
to a single giant lump of copper buried in steel.

Cheers,
James

Utility transformers are very efficient, over 99%. They eliminate
surface area from the efficiency tradeoff by oil cooling, sometimes
with radiators and fans.

Absent concern about cooling, the matrix thing sort of collapses with
the observation that all the windings can share one core.

Flex PCB winding transformers are neat. Power densities are
outrageous.

https://www.coilcraft.com/en-us/products/transformers/planar-transformers/

Hey, are these new?

https://www.coilcraft.com/en-us/products/power/coupled-inductors/1-1-shielded-coupled/lpd_v/lpd8035v/

1500 volt dual inductors!






--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

On Friday, August 7, 2020 at 11:03:04 AM UTC-4, jla...@highlandsniptechnology.com wrote:

On Fri, 7 Aug 2020 06:59:00 -0700 (PDT), dagmargoodboat@yahoo.com
wrote:

On Wednesday, August 5, 2020 at 7:38:00 PM UTC-4, John Larkin wrote:

Cooling depends on surface area. You get more surface area by adding
more copper, and that relationship is not linear (the volume-surface
thing, like mice and elephants) so core loss might require a lot of
expensive copper.

I\'m intrigued by the matrix transformer concept: two transformers
with primaries in series and secondaries in parallel have both 1/4th
the i^2*r losses each, and more dissipation surface per watt compared
to a single giant lump of copper buried in steel.

Cheers,
James

Utility transformers are very efficient, over 99%. They eliminate
surface area from the efficiency tradeoff by oil cooling, sometimes
with radiators and fans.

Absent concern about cooling, the matrix thing sort of collapses with
the observation that all the windings can share one core.

Well sure they can use one core, that\'s where we started. The matrix
transformer gets its advantages from /distributing/ the core and the
windings.

- Heat is spread out over more area, and current-sharing reduces i^2*r
loss in each transformer-element.

- Leakage inductance is proportional to turns^2, which is reduced
by 1/n when you split, e.g., the secondary into n sections on
separate cores.

- And of course switching loss is lowered, since leakage inductance
energy is lost to the snubber each cycle in most switchers.

You could make GaN switchers run at super speeds.

A further advantage of low leakage inductance claimed is that the
primary and secondary currents are in such tight phase, that the
primary winding and synchronous rectifier on the output can share
the exact same timing.

Flex PCB winding transformers are neat. Power densities are
outrageous.

https://www.coilcraft.com/en-us/products/transformers/planar-transformers/

I was surprised to read recently that transformers\' power-handling
capabilities aren\'t core-size limited, but by one\'s ability to get
out the heat (core-loss, and i^2*r).

Hey, are these new?

https://www.coilcraft.com/en-us/products/power/coupled-inductors/1-1-shielded-coupled/lpd_v/lpd8035v/

1500 volt dual inductors!

That\'s a nice upgrade. Best I\'ve seen \'til now were 500V.

Cheers,
James

 

[John Larkin]

On Fri, 7 Aug 2020 13:51:22 -0700 (PDT), dagmargoodboat@yahoo.com
wrote:

On Friday, August 7, 2020 at 11:03:04 AM UTC-4, jla...@highlandsniptechnology.com wrote:
On Fri, 7 Aug 2020 06:59:00 -0700 (PDT), dagmargoodboat@yahoo.com
wrote:

On Wednesday, August 5, 2020 at 7:38:00 PM UTC-4, John Larkin wrote:

Cooling depends on surface area. You get more surface area by adding
more copper, and that relationship is not linear (the volume-surface
thing, like mice and elephants) so core loss might require a lot of
expensive copper.

I\'m intrigued by the matrix transformer concept: two transformers
with primaries in series and secondaries in parallel have both 1/4th
the i^2*r losses each, and more dissipation surface per watt compared
to a single giant lump of copper buried in steel.

Cheers,
James

Utility transformers are very efficient, over 99%. They eliminate
surface area from the efficiency tradeoff by oil cooling, sometimes
with radiators and fans.

Absent concern about cooling, the matrix thing sort of collapses with
the observation that all the windings can share one core.

Well sure they can use one core, that\'s where we started. The matrix
transformer gets its advantages from /distributing/ the core and the
windings.

- Heat is spread out over more area, and current-sharing reduces i^2*r
loss in each transformer-element.

- Leakage inductance is proportional to turns^2, which is reduced
by 1/n when you split, e.g., the secondary into n sections on
separate cores.

- And of course switching loss is lowered, since leakage inductance
energy is lost to the snubber each cycle in most switchers.

You could make GaN switchers run at super speeds.

A further advantage of low leakage inductance claimed is that the
primary and secondary currents are in such tight phase, that the
primary winding and synchronous rectifier on the output can share
the exact same timing.

Flex PCB winding transformers are neat. Power densities are
outrageous.

https://www.coilcraft.com/en-us/products/transformers/planar-transformers/

I was surprised to read recently that transformers\' power-handling
capabilities aren\'t core-size limited, but by one\'s ability to get
out the heat (core-loss, and i^2*r).


Hey, are these new?

https://www.coilcraft.com/en-us/products/power/coupled-inductors/1-1-shielded-coupled/lpd_v/lpd8035v/

1500 volt dual inductors!

That\'s a nice upgrade. Best I\'ve seen \'til now were 500V.

Cheers,
James

They don\'t spec max winding voltage. They are sending me 10 samples on
the condition that I blow up a couple.

 

[Tabby]

On Friday, 7 August 2020 22:09:56 UTC+1, John Larkin wrote:

On Fri, 7 Aug 2020 13:51:22 -0700 (PDT), dagmargoodboat@yahoo.com
wrote:
On Friday, August 7, 2020 at 11:03:04 AM UTC-4, jla...@highlandsniptechnology.com wrote:

Hey, are these new?

https://www.coilcraft.com/en-us/products/power/coupled-inductors/1-1-shielded-coupled/lpd_v/lpd8035v/

1500 volt dual inductors!

That\'s a nice upgrade. Best I\'ve seen \'til now were 500V.

Cheers,
James

They don\'t spec max winding voltage. They are sending me 10 samples on
the condition that I blow up a couple.

Years ago I discovered from hipot testing transformers that it was too easy for them to suddenly not withstand as much voltage any more. The 1 person manufacturing line swore nothing had been changed.


NT

 

[Phil Allison]

legg wrote more absurd crap:

============================

For windings, it\'s a \'fill factor\'.

If you check the ratio of copper vs air in the inner
diameter of a toroid, as the fill approaches a certain
percentage, you\'ll see a diminishing return for agravated
difficulty in fabrication.

** Cost is everything in manufacture.

But as here like to consider what physics allows, it is clearly a fact that filling a toroidal with as much copper as possible maximises the VA for a given core.

This IS the practice for all other types of core shape.

Most toroidals are low and flat - again not optimum but liked by many customers. Same goes for R-cores and U cores which result in low height products.


Those last few turns also have the longest length
per turn, further diminishing their \'return\'.

** What utterly stupid garbage.

One fills the available space by using the heaviest gauge wire possible - not by increasing the turns - that is already set by the core cross section, voltage and frequency.

Yo have no point to make and just post bullshit for the sake of having the last word and big noting your pathetic self.

FOAD you ridiculous ass.


...... Phil

 

[legg]

On Fri, 7 Aug 2020 17:15:53 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

legg wrote more absurd crap:

============================


For windings, it\'s a \'fill factor\'.

If you check the ratio of copper vs air in the inner
diameter of a toroid, as the fill approaches a certain
percentage, you\'ll see a diminishing return for agravated
difficulty in fabrication.

** Cost is everything in manufacture.

But as here like to consider what physics allows, it is clearly a fact that filling a toroidal with as much copper as possible maximises the VA for a given core.

This IS the practice for all other types of core shape.

Most toroidals are low and flat - again not optimum but liked by many customers. Same goes for R-cores and U cores which result in low height products.


Those last few turns also have the longest length
per turn, further diminishing their \'return\'.


** What utterly stupid garbage.

One fills the available space by using the heaviest gauge wire possible - not by increasing the turns - that is already set by the core cross section, voltage and frequency.

Yo have no point to make and just post bullshit for the sake of having the last word and big noting your pathetic self.

FOAD you ridiculous ass.


..... Phil

If the MLT drops 20%, You get the same loss with 20% reduction
in copper x-section.

Not so?

RL

 

[Jasen Betts]

On 2020-08-07, dagmargoodboat@yahoo.com <dagmargoodboat@yahoo.com> wrote:

On Wednesday, August 5, 2020 at 7:38:00 PM UTC-4, John Larkin wrote:
On Wed, 5 Aug 2020 23:32:02 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

I think people design transformers for
equal copper loss in the primary and secondary

BTW, what is the source of this and similar rules of thumb (e.g. equal
copper and core losses)? Logic says that one should always design for
minimal total losses, given the economic constraints.

Best regards, Piotr

I don\'t think transformers are usually designed for equal core and
copper losses. This one runs cold at full AC voltage but no load.

They are designed for equal primary and secondary copper losses at
full load, I think.

Cooling depends on surface area. You get more surface area by adding
more copper, and that relationship is not linear (the volume-surface
thing, like mice and elephants) so core loss might require a lot of
expensive copper.

I\'m intrigued by the matrix transformer concept: two transformers
with primaries in series and secondaries in parallel have both 1/4th
the i^2*r losses each, and more dissipation surface per watt compared
to a single giant lump of copper buried in steel.

It seems to me that you\'d get most of those benefits buy just using a
single transforer of twice the mass. I think you may be counting
some of the gains twice.

--
Jasen.

 

[Cydrome Leader]

jlarkin@highlandsniptechnology.com wrote:

On Thu, 6 Aug 2020 06:57:07 +0000 (UTC), Cydrome Leader
presence@MUNGEpanix.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Wed, 5 Aug 2020 01:21:10 -0700 (PDT), Phil Allison
pallison49@gmail.com> wrote:

Cydrome Leader is Funny:

=======================

So I ran it for a few hours with 10 amps DC in the primary. Temp rise
was about 26C in free air. I think people design transformers for
equal copper loss in the primary and secondary, so temp rise would
double when loaded in the system.

What about the heat generated by losses in the secondary?


** Doubles the temp rise - as JL just claimed.


https://www.dropbox.com/s/ylm8dc1e14dwv7y/P900_Xfmr_Thermal.jpg?raw=1

https://www.dropbox.com/s/5b55ybfoq2pkp9v/P900_Xfmr_Thermal_2.jpg?raw=1

You can even see on the label (looks sort of like a Noratel) the input is
266VA and output is rated 240VA. So depending on power factor at full
load, it could be upto 26 watts of loss, although I doubt a toroid that
size would have such a poor efficiency. The iron losses will surely be
less than 50% on a toroid. Maybe the maker can tell you the ratio?


This transformer was made for us by Amgis. I specified it so I know
the ratios: 1 : 1.4 : 1.4 : 1.4 : 1.4. We have a relay board that
switches the secondaries to get four output voltage ranges.

Are these ratios exact or is there a fudge factor for losses at rated
load?

Exact turns ratio. We know the other parameters: wire resistance, mag
inductance, leakage inductance, SRF, saturation. We plug all that into
the system Spice model.

How did that work out? Did you give rought specs and the then the
manufacture provided full expected specs?

Just curious. Retired transformer designer friend seemed to spend a
bit of his time trying to get \"the facts\" from customers to make designs
that would actually work under load. The stubborn customers would get full
production runs of stuff that met specs, but didn\'t work for the
application.

** PF has no effect - VA is all that matters, effectively just the RMS current. Iron losses are a watt or so per kg or iron. I mag is tiny.

So 20 watts copper loss, 6 watts for iron.

Regulation about 8%.

Toriods are very simple.


.... Phil

Unloaded, the AC operating primary current is essentially zero, so I
don\'t think core loss is significant.

As an alternator simulator, voltage increases with frequency, which
keeps Imag low on the low end.

It\'s a weird application. We specialize in weird.

Was amgis friendly about making samples?

Not free samples, but I didn\'t ask for that. We placed a PO that
included a few first-articles for verification, with the rest shipped
on approval.

Sounds reasonable.

 

[Cydrome Leader]

Phil Allison <pallison49@gmail.com> wrote:

Cydrome Leader is an IDIOT wrote:

================================



So I ran it for a few hours with 10 amps DC in the primary. Temp rise
was about 26C in free air. I think people design transformers for
equal copper loss in the primary and secondary, so temp rise would
double when loaded in the system.

What about the heat generated by losses in the secondary?


** Doubles the temp rise - as JL just claimed.

It sounded like the double the heat assumption was from the 50% of losses
being in the iron, when the transformer is used with AC.

** You on drugs ??


Even if you
double the primary resistive loses to account for the secondary, the core
is still being left out. That\'s how I read it.

** JL neglected it as he knows it is trivial.



As for the PF has no effect statement, I\'ve never really understood the
point on the VA in and VA out ratings on some toroidal transformers.
Isolation transfomers are usually marked in a more sensible way like
\"input 120VAC 8.4A, output 120VAC 8.0A\". While these are safe use ratings,
it still doesn\'t answer the question about efficiency at no to full load.
You can only guess the worst case heat losses.


** My god you are stupid.

Max heat loss happens at max load, always.

Wow, you\'re finally catching up. Now go ahead and re-read my comment about
the sillyness of VA in and VA out ratings on small toroidal transformers.

 

[Cydrome Leader]

legg <legg@nospam.magma.ca> wrote:

On Thu, 6 Aug 2020 16:41:03 -0700 (PDT), Phil Allison
pallison49@gmail.com> wrote:

legg wrote:

==========


For windings, it\'s a \'fill factor\'.

If you check the ratio of copper vs air in the inner
diameter of a toroid, as the fill approaches a certain
percentage, you\'ll see a diminishing return for agravated
difficulty in fabrication.

** Cost is everything in manufacture.

But as here like to consider what physics allows, it is clearly a fact that filling a toroidal with as much copper as possible maximises the VA for a given core.

This IS the practice for all other types of core shape.

Most toroidals are low and flat - again not optimum but liked by many customers. Same goes for R-cores and U cores which result in low height products.



.... Phil

Those last few turns also have the longest length
per turn, further diminishing their \'return\'.

The \'practice\' is to assume a fill factor of less
than 80%, to allow for insulation, wire shape and
cover. For mains voltage wall thickness, creepage
spacing, and bobbin tolerancing, it\'s even worse.

Toroids depend upon 3xlayer film overlapping weave for
reinforced layering and core or outer wrap, though
some cores use fitted caps at the expense of efficiency.

Low and flat toroids are a \'style\' (at the expense of
efficiency) - the most efficient physical ratio being
roughly 2.2:1 / OD:H.

High frequency stuff . . . .

RL

How would you rate this cutie?

https://www.overunity.com/7833/thane-heins-bi-toroid-transformer/dlattach/attach/48359/image/

I didn\'t look at the site, but it\'s clearly some free energy nonsense
project. Maybe the entire thing spins on a tesla turbine or overbalance
wheel.

I like how it\'s the most complicated way to come up with a three legged
tape wound core.

 

[Phil Allison]

Cydrome Leader is a retarded NUT case wrote:


===========================================

** You on drugs ??


** My god you are stupid.

Max heat loss happens at max load, always.

Wow, you\'re finally catching up.

** I\'m way ahead of morons lie you.

Now go ahead and re-read my comment about
the sillyness of VA in and VA out ratings on small toroidal transformers.

** You never made any.



..... Phil

 

[server]

On Sat, 8 Aug 2020 05:54:48 +0000 (UTC), Cydrome Leader
<presence@MUNGEpanix.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 6 Aug 2020 06:57:07 +0000 (UTC), Cydrome Leader
presence@MUNGEpanix.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Wed, 5 Aug 2020 01:21:10 -0700 (PDT), Phil Allison
pallison49@gmail.com> wrote:

Cydrome Leader is Funny:

=======================

So I ran it for a few hours with 10 amps DC in the primary. Temp rise
was about 26C in free air. I think people design transformers for
equal copper loss in the primary and secondary, so temp rise would
double when loaded in the system.

What about the heat generated by losses in the secondary?


** Doubles the temp rise - as JL just claimed.


https://www.dropbox.com/s/ylm8dc1e14dwv7y/P900_Xfmr_Thermal.jpg?raw=1

https://www.dropbox.com/s/5b55ybfoq2pkp9v/P900_Xfmr_Thermal_2.jpg?raw=1

You can even see on the label (looks sort of like a Noratel) the input is
266VA and output is rated 240VA. So depending on power factor at full
load, it could be upto 26 watts of loss, although I doubt a toroid that
size would have such a poor efficiency. The iron losses will surely be
less than 50% on a toroid. Maybe the maker can tell you the ratio?


This transformer was made for us by Amgis. I specified it so I know
the ratios: 1 : 1.4 : 1.4 : 1.4 : 1.4. We have a relay board that
switches the secondaries to get four output voltage ranges.

Are these ratios exact or is there a fudge factor for losses at rated
load?

Exact turns ratio. We know the other parameters: wire resistance, mag
inductance, leakage inductance, SRF, saturation. We plug all that into
the system Spice model.

How did that work out? Did you give rought specs and the then the
manufacture provided full expected specs?

Pretty much. I specified the voltages, power levels, turns ratio,
frequency range, and suggested a stock Hammond part as being about the
right size and mounting. The Hammond part guided me as to what was
reasonable; I didn\'t have to do any real magnetics calculations, just
scale that transformer a little. They responded with a more detailed
spec with resistances, inductances, wire colors, things like that.
That looked good so I told them to go.

Just curious. Retired transformer designer friend seemed to spend a
bit of his time trying to get \"the facts\" from customers to make designs
that would actually work under load. The stubborn customers would get full
production runs of stuff that met specs, but didn\'t work for the
application.

** PF has no effect - VA is all that matters, effectively just the RMS current. Iron losses are a watt or so per kg or iron. I mag is tiny.

So 20 watts copper loss, 6 watts for iron.

Regulation about 8%.

Toriods are very simple.


.... Phil

Unloaded, the AC operating primary current is essentially zero, so I
don\'t think core loss is significant.

As an alternator simulator, voltage increases with frequency, which
keeps Imag low on the low end.

It\'s a weird application. We specialize in weird.

Was amgis friendly about making samples?

Not free samples, but I didn\'t ask for that. We placed a PO that
included a few first-articles for verification, with the rest shipped
on approval.

Sounds reasonable.

I\'d used them before, and the production requirement was real, so that
was a good way to work with them.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

On Thu, 6 Aug 2020 03:57:22 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

Cydrome Leader is an IDIOT wrote:

================================



So I ran it for a few hours with 10 amps DC in the primary. Temp rise
was about 26C in free air. I think people design transformers for
equal copper loss in the primary and secondary, so temp rise would
double when loaded in the system.

What about the heat generated by losses in the secondary?


** Doubles the temp rise - as JL just claimed.

It sounded like the double the heat assumption was from the 50% of losses
being in the iron, when the transformer is used with AC.

** You on drugs ??

I am!



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard