Physical difference between low/high transformers?

[cjdelphi]

I tried googling it, but it's obscure ..

Is there a pychical difference between a high frequency transformer and a low one (mains 50/60hz)

Are the cores different?

Eg what happens if i take a huge old transformer designed (and by this, precisely what is the difference?) For mains and switched it fast...

Would i get more current and less heat?

 

[hevans1944]

Since the primary inductance is an increasing function of frequency, you might have trouble getting enough current switching it fast. The "fly-back" voltage would also be larger for any given switching current. The hysteresis losses will be terrible. That's why high-frequency cores use non-conductive ferrite. But go ahead and try it. That's how you learn. And you might try searching with real words, i.e., replace "pychical" with "physical" for more results.

 

[duke37]

I do not know the psychic difference between the transformers but here is a reading of my crystal ball.

The frequency and voltage determines the flux which will be set by the numer of turns. The iron cores are split into laminations to reduce the eddy currents and the thinner the lamination, the better. Toroidal cores only have one lamination of very thin metal wound round and round.
The higher the frequency, the lower number of turns necessary and aircraft used 400Hz to reduce weight.
Switch mode power supplies use a very high frequency, maybe 100kHz, and a small ferrite core and very few turns.

 

[cjdelphi]

You answered the question by explaining a different core was used, thank you...

 

[cjdelphi]

I do not know the psychic difference between the transformers but here is a reading of my crystal ball.

The frequency and voltage determines the flux which will be set by the numer of turns. The iron cores are split into laminations to reduce the eddy currents and the thinner the lamination, the better. Toroidal cores only have one lamination of very thin metal wound round and round.
The higher the frequency, the lower number of turns necessary and aircraft used 400Hz to reduce weight.
Switch mode power supplies use a very high frequency, maybe 100kHz, and a small ferrite core and very few turns.

Different core material is the answer... after all copper wire is still just copper wire nothing else is different. .

 

[cjdelphi]

I'm obviously of the few who use a mobile device to type on and android auto corrects it without my knowledge hence that typo...

 

[hevans1944]

I'm obviously of the few who use a mobile device to type on and android auto corrects it without my knowledge hence that typo...

Typos are the norm for mobile devices. I apparently have fat fingers, so I avoid using my Galaxy 4 "smart phone" for typing in anything much more complicated than a telephone number or an e-mail address. IMs (Instant Messages) for me are a PITA. However, most of the time the intent is clear from the context, as was yours. Still... a psychic transformer would be a hot seller in some circles. Maybe I'll look into that.

 

[(*steve*)]

Different core material is the answer... after all copper wire is still just copper wire nothing else is different. .

Number of turns will also be very different.

Bifilar windings (that my phone really wants to call "Butler soundings") are also more often used.

 

[Colin Mitchell]

The difference has been omitted in all of the above.
The core of a low frequency transformer has lamination and the magnetic flux that is passed the core from the winding, passes across these laminations and produces a small current in each of them. This current produces a small amount of heat. The lamination actually creates what is known as a SHORTED TURN. The only reason why the lamination does not get too hot is due to the resistance of the shorted turn and the small amount of flux that passes across the lamination.
If you increase the frequency, the peak amount of current will be produced more often per second and the lamination will get hotter.
This action takes energy from the primary and the core overheats.
To prevent this from happening in a high frequency transformer, the laminations are cut up into very small pieces so that less flux will pass through each piece. The laminations are now called "a ferrite material" and the outside of each piece has an oxide or insulating layer so the current does not pass from one particle to the next.

 

[(*steve*)]

Colin, I think you may have omitted to read the very first reply. And the second.

 

[duke37]

@cjdelphi
If I upset you, I am sorry. This was not my intention, just that some typos are quite amusing. I produce lots of typos and try to correct them but one always seems to get away.

I would disagree with Colin in one respect, The laminations are made as thin as is possible for assembly but one wound lamination in a toroid or C core can be thinner than E/I laminations and can also have an optimal aligned structure.
To go even further, powdered iron often produced by the carbonyl process can be used. This will be alpha iron with a body centred cubic structure, called ferrite. This is not the same as the ferrites used in magnetic cores which are bulk materials with a high resistance and are not made in laminations.

Audio output transformers are a science in themselves because they have to handle a very wide range of frequencies.