Motor to generator mains regenerator.

[Pano]

Though the V-20 quad-turbo engine sounded great spooling-up under load...

Ooooooo..... Fun audio of another kind.

 

[esl 63]

I have used an old regenarator motor+generator on same axel, givin 3phase 400Hz out.
Works great!

Only one problem... the sound from it... bad bearings i guess.
Maybe if i place it in the basement the S/N ratio would be acceptable.

Today i have separate isolation transformers to all my equipment. In total 7 transformers.
All of them have static shielding between prim and sec windings.
All transformers also have separate hf filter on the input.
Secondary grounding is taken from the center taps. But NO equipment ground is connected to the mains ground! VERY important.

This way, no ground loops occur...
During testing and evaluation i found that some HiFi products connected to the isolation transformer created some ringing, which was reduced by an RC filter over the secondary winding 100ohm//10uF.

 

[AndrewT]

But NO equipment ground is connected to the mains ground! VERY important.

This way, no ground loops occur...

Two problems.
1. All ClassI equipment must be connected to PE.
2. dispensing with the PE connections does not result in

no ground loops occur...

 

[d a o]

hi

What is the cheapest and easiest way to create
400 Hz pure sine
230 volts
500 - 1000 watts

not to break the thread,
but maybe someone knows?

 

[imix500]

Yeah, gotta agree with Andrew. Ground as an alternative return path MUST be maintained as per NEC. When I have built and used 200A 3Ph iso transformers the ground is passed through with nothing but a lug to attach to the transformer case. The entertainment industry has learned that most of the noise that affects audio is carried on the neutral and that's why iso transformers work- they create a new neutral that is bonded to ground at the point of creation.

 

[Arty]

Hi Arty, a set of forklift batteries to derive say +-48VDC from will cost quite a bit more that the complete audio system. Yes it would be the ultimate power source. How would you handle the rest of the equipment, say the CD player, DAC, etc - remove each power supply and tap of the required voltage from the battery bank, i.e. 5V, +12V,-12V?

correct, tap what You need.
allso, forklifer battery is the best bet, i would say that a decent audio setup of a cd player, a pre-amp, and a 2 channel chipamp will be happy with bike baterrys..
something like that can be made for +- 24 V like.. 100 usd or so.
or even less, if you use speakers, and not space heaters

 

[esl 63]

To generate your own new PE ground is very common when you want to surpress noice from power grid. In hospitals laboratories and for some computer stuff etc...
I have been working with this and its quite common to generate a floating ground.
More to read here: EN61558-2-19
And here: http://www.conceptorg.com/techlibrary/PowerTechnology/Powerline_Noise_Supression.pdf

I have more than 140dB reduction of assymetric noice and 80dB reduction at 100kHz symmetric noice. This is possible since there is an electrostatic shielding betveen primary and secondary winding.
Cheeper more quiet than a 400Hz motor/generator. Been there done that and got the T-shirt...

 

[phaselag]

Your idea is existing technology. At least one company makes a large synchronous motor-generator, with a flywheel attached to the shaft. When power is present the motor spins the flywheel at 1800 or 3600 RPM. When power fails, the flywheel drives the synchronous motor which now runs as a generator. A hot start diesel engine is started and takes over the load within about 30 seconds. Only 1 or 2 hetrz frequency drop in the process. These systems are used in power critical applications, like telecom switching centers. We have worked with a few of them, in the 100 KW+ size.

paul