An interesting solution is to buy a cheap 500VA UPS and modify/wire it to produce a US mains voltage output (it probably might include this option already if you choose the right type) then change the working frequency to 400Hz or whatever. If the input/output voltage circuitry is too complicated and dictates inseparable Vin=Vout then drive it via a 115V auto-transformer. You may have to modify the output filtering to allow the 400Hz output but that will be fairly easy.

Allan G3PIY

Does anyone have any ideas about how to replicate an 'aircraft mains' supply when required by an older piece of equipment? A sensible idea would be to change the mains transformer etc. but these can be difficult to source for the more complex machines. I've heard ideas for building large MOSFET amps to deliver around 200 wattrs of power (for one of my sets I need around 190W at 110V)  Are there any more simple or practical ideas? Someone I know suggested a manufactured PSU for variable frequencies and voltages, but on investigation, these seem to be very expensive. Any ideas please?

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Hi Adam

Correct me but I thought the transformer cores used in a 50 hz transformer are different to those used in a 400 hz transformer 

and the loses in a 50 hz transformer are grater if used at 400 hz

The problem is getting 400hz 3 phase as there are lodes of solutions for 400hz single phase most of them having an input voltage of 24 volts DC

a possible solution for a home made unit is to get hold of the aircraft rectifier unit 120 volts input 3 phase at 400 hz for charging the 24 volt system as they have a 3 phase winding on the primary and secondary

Regards Paul l

An interesting solution is to buy a cheap 500VA UPS and modify/wire it to produce a US mains voltage output (it probably might include this option already if you choose the right type) then change the working frequency to 400Hz or whatever. If the input/output voltage circuitry is too complicated and dictates inseparable Vin=Vout then drive it via a 115V auto-transformer. You may have to modify the output filtering to allow the 400Hz output but that will be fairly easy.

Allan G3PIY

Does anyone have any ideas about how to replicate an 'aircraft mains' supply when required by an older piece of equipment? A sensible idea would be to change the mains transformer etc. but these can be difficult to source for the more complex machines. I've heard ideas for building large MOSFET amps to deliver around 200 wattrs of power (for one of my sets I need around 190W at 110V)  Are there any more simple or practical ideas? Someone I know suggested a manufactured PSU for variable frequencies and voltages, but on investigation, these seem to be very expensive. Any ideas please?

Moderator's Note: Please sign your posts!

Hi if you want to power synchro's then I would use a power inverter from a plain    this is work I want to do also

Paul

For many years I've been after the same thing; I need 250ma at 115V ~400 single phase. This is a hobby so I'd prefer to build rather than buy. Would it not be possible to use a vibratory PSU type arrangement? I'd imagine it would have to be a solid state vibrator in order to home in on 400Hz. Perhaps an expert with solid state vibrators could tell us. But would a regular vibrator transformer be okay with that frequency? I have a number of vibrator transformers laying about including one from the Larkspur C42 set but have never gotten around to experimenting. I guess there's also the question of waveform you'd get from a vibrator. I'm interested in powering synchro's so I suspect they want a reasonable sine wave.

Dan

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Hi andy 

Thank you for the explanation mainly the turns ratio  being 8 times grater in a 50 Hz transformer that Is new to me

 but I already realised about using a 400hz transformer at 50 hz

Regards Paul

The main difference between a 50Hz transformer and a 400Hz transformer is that the turns-per-volt is eight times greater at 50Hz than it is at 400Hz. Whilst a 50Hz transformer will run less efficiently at 400Hz, there's every chance you'll get away with it unless you're 'squeezing the pips'. It will be bigger and heavier than you need.
What is a definite no-no is running a transformer at a lower frequency than it is designed for, it will rapidly overheat and burn out.

Andy
M0FYA

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Some of the reasonably priced automotive inverters that change 12VDC to 60 Hz by stacking square waves to simulate a sine wave. The basic frequency of a square wave is controlled by a single capacitor. If you reduce the size (capacitance) of this capacitor you increase the frequency. In my case I used a 25W inverter which Canadian tire sells for about $15 when on sale. I changed a 0.1 uF to .005UF. I never checked efficiency.

 Running a 60 Hz transformer has increased copper (resistance) losses because there are far more turns on the winding than needed. In fact a 60 Hz 120 Volt primary will be OK with 600 volts at 400Hz. As a corollary the highest voltage on a 120 V 400 Hz winding is about 18 V 60Hz. 

Those automotive inverters are available up to 1kW and maybe higher.  

Wally VE7HEW

Hi Richard

Thank you for posting this will keep it for another day

Paul b

See http://www.ccae.tm6cca.com/DOWN/CCAE%20-%20CONVERTER%2024V%20400HZ%20-%20F6FER.pdf
73, Richard, F4WCD/ZS6TF

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Hi Wally   that is good  but at that power most radio equipment requires 3 phase

Some of the reasonably priced automotive inverters that change 12VDC to 60 Hz by stacking square waves to simulate a sine wave. The basic frequency of a square wave is controlled by a single capacitor. If you reduce the size (capacitance) of this capacitor you increase the frequency. In my case I used a 25W inverter which Canadian tire sells for about $15 when on sale. I changed a 0.1 uF to .005UF. I never checked efficiency.

 Running a 60 Hz transformer has increased copper (resistance) losses because there are far more turns on the winding than needed. In fact a 60 Hz 120 Volt primary will be OK with 600 volts at 400Hz. As a corollary the highest voltage on a 120 V 400 Hz winding is about 18 V 60Hz. 

Those automotive inverters are available up to 1kW and maybe higher.  

Wally VE7HEW

Happens a lot with some 240v US equipments using 60Hz transformers on UK mains.

Lots of nasty humming. Both my HT37s now have duff transformers

Allan G3PIY

The main difference between a 50Hz transformer and a 400Hz transformer is that the turns-per-volt is eight times greater at 50Hz than it is at 400Hz. Whilst a 50Hz transformer will run less efficiently at 400Hz, there's every chance you'll get away with it unless you're 'squeezing the pips'. It will be bigger and heavier than you need.
What is a definite no-no is running a transformer at a lower frequency than it is designed for, it will rapidly overheat and burn out.

Andy
M0FYA

Hi Andy 

Sorry for the typo  I did mean turns per volt  on the windings  and hence the reason for  400 Hz transformers being smaller than their 50 Hz  equivalent

Regards Paul

Paul,
The turns ratio remains the same, that is the ratio of the input and output voltages, it's the turns per volt on all windings which is inversely proportional to frequency (assuming all other parameters remain the same).
Andy
M0FYA

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Hi Standard AC motor inverter’s  have a output frequency of 50 Hz  or 60 Hz  are you saying the AC Tech/Lenze models goes to 400Hz

Paul

Try an industrial AC motor inverter. These are available with single phase input and give three phase output at whatever frequency and voltage you set it for. We used to use AC Tech/Lenze models. They are at the cheap and cheerful end of the market and I seem to remember start around 0.3 Kw.
Gordon
G7KNS

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They often go BANG!!! Including the one controlling the nursing home lift where the matron decided to take a horse up to the top floor to celebrate an inmate’s birthday. One horse >> 10 people?

Plenty around on Ebay

http://www.radiomuseum.co.uk/lifts.html

Allan G3PIY

From: wireless-set-no19@groups.io [mailto:wireless-set-no19@groups.io] On Behalf Of cwlathes
Sent: 07 November 2020 12:17
To: wireless-set-no19@groups.io
Subject: Re: [wireless-set-no19] 100V 400hz aircraft supplies

I think we are talking VFD – Variable frequency Drive

The Hitachi and Yaskawa models I am familiar with have a frequency range of 0,1 – 400Hz

Regards,

Carvel

ZR6APX