Mains transformer for 50Hz and 400Hz use?

Nigel Goodwin said:

but what's the difference in the transformers?, it's basically copper windings on a similar core,

Click to expand...

Audio transformers are wound to minimize leakage inductance and stray capacitance, which can cause resonances in the frequency response.

what exactly do you want?

A question, the OP stated "Mains Transformer". Do you mean a transformer in a piece of equipment that converts the mains voltage to a lower (or higher) voltage to run the internal circuitry?
Or a mains transformer that supplies a residency with 120 volts or 240 volts (or both in the U.S.), after stepping down the high tension (4160 volts, 12,000 volts or higher) power that is distributed by a utility company?

A question, the OP stated "Mains Transformer". Do you mean a transformer in a piece of equipment that converts the mains voltage to a lower (or higher) voltage to run the internal circuitry?

Click to expand...

...thanks, yes thats right....its for a DC power supply.

If it is for a DC power supply why not use a switched mode power supply so there is no transformer working at mains frequency. If you used a switch mode power supply the mains is first rectified so the input frequency would not matter. (Within reason.)

Les.

Thanks, this application needs low noise.

Still haven't been told a good reason to have the supply operate from 50Hz to 400Hz mains.
The requirement for such a supply would be very limited.

Still haven't been told a good reason to have the supply operate from 50Hz to 400Hz mains.
The requirement for such a supply would be very limited.

Click to expand...

I agree, someone wanted to label the (50Hz) product as 50Hz to 400Hz, but it seemed a poor idea

Buk said:

I suspect that audio transformers 'get away with it', because unlike an AC supply voltage, the signal they carry is not a pure sine wave; but I do not know enough on the subject to justify that suspicion.

But I will find out.

Click to expand...

Audio transformers used in what was the common upper power range of 50 watts continuous had primary voltages in the area of about 450 volts and therefore had low current draw. Not very useful for a "mains transformer".

A possible answer would be to have an inverter using 50 or 60 Hz input frequency and 50 or 60 and 400 Hz outputs. Of course you wouldn't really need to invert then re-establish the 50 or 60 Hz power, since you already have it.
In the industry 400 Hz power is produced by means of purpose built AC generators, rotary converters (motor-generators), and static inverters.
If your business/industry requires 400 Hz AC power, you would produce it by one of these methods.
In the past it was also possible to produce 400 Hz power from DC in the form of a square wave (or near square wave usually) by means of electro-mecanical vibrators feeding transformers, albeit again with limited power output capability.

crutschow said:

Still haven't been told a good reason to have the supply operate from 50Hz to 400Hz mains.
The requirement for such a supply would be very limited.

Click to expand...

A repair or production facility where avionics and aircraft electrical equipment is manufactured and or maintained, but the 400 Hz power would be derived from a purpose built generator, rotary frequency converter in the form of a motor generator, or a static inverter. So besides the last two options being powered by a 50 or 60 Hz electrical service there is no commonality to the electrical systems or equipment there.

The only 400Hz transformers I ever saw were military to save space and weight. 50 years ago I had a 400Hz dynamotor generator that run off of a car battery it produced 120vac.