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May I make a rotary converter who may work as a generator during power outs?

Dag S K

Aluminum
Joined
Aug 22, 2007
Location
Norway
If I make a rotary converter with 3 phase out may I make it to work as a generator by power from a tractor if I have the correct speed?

If yes, do you have examples of how to solve it. For me 3 kVA would be enough, more will be just fine.

dsk
 
Induction motors don't work well as stand-alone generators unfortunately. They don't have a means to generate their own field, they just react to the input field.

I think there are ways with using capacitors to supply it the reactive current to run the field, but I believe voltage regulation ends up *very* poor.

It might be possible with a pile of power electronics.
 
You would need to use a synchronous generator to provide the excitation, since the induction 'generator' in a normal phase converter does not provide accurate excitation to produce the output voltage and supply reactive VARs without having the mains supply working.

You could do this by driving a generator with an induction motor for normal use and using the tractor PTO (geared up from 540 or 1000 to 1500 rpm) when there is no mains power. If you do this, the output frequency will be a few percent low when powered from the mains, but not enough to cause problems wiith machine tools. The efficiency would also be a bit lower.

Note:- you can also use the synchronous generator on its own as the phase converter. If you do this, you will need to make sure that the exciter gets its reference voltage from the generated phases and not the input phase.
 
If I make a rotary converter with 3 phase out may I make it to work as a generator by power from a tractor if I have the correct speed?

If yes, do you have examples of how to solve it. For me 3 kVA would be enough, more will be just fine.

dsk

Not anywhere near worth the bother.

What you do instead is very simple.

Acquire a "generator head". It's what they are made for.
Those who sell them also sell regulators and such.

3 KVA range are not terribly expensive. See "Mecce Alta" for a popular one.

Mecc Alte | The Largest Independent Producer of Alternators

Even if not a practical source for Norway, there is a lot of useful information here to expand your understanding:

Generator Heads – Generator Parts | Central Georgia Generators

For a PTO, you will "probably" also need pulleys to change the RPM.

Gen heads for 60 Hz output are most commonly available @ 3600 RPM, @ 1800 RPM, and @ 900 RPM.

For 50 Hz, same hardware, lower input RPM, as expected!

:)

Low KVA sizes, you might only find the two higher RPM 2 pole and 4 pole ones.

CAVEAT: While many, if not most, may be selective configured for all 120 single-phase, 120-0-120 // 240 split phase, and/or 208 Wye or 240 Delta 3-Phase, what serves for standby or emergency power to keep lights on and beer cold or operate woodworking tools doesn't do as well at powering metalworking machine-tools.

To run a shop, significant gen set oversizing is wise to insure it can manage starting loads and sustain stability in the cut as workloads vary.
 








 
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