Using 400hz deisel generator for home use 4

[filbert72]

I have a 10KW military generator that I would like to adapt to home use. It is a 400hz unit that provides 120 V 1 phase, 240 V 1 phase, or 120/208V 3 phase. What issues must be addressed to run 60hz equipment on 400hz power, or to change 400hz power to 60hz? Will any home appliances function with 400hz power?

 

[itsmoked]

There are three methods, none are cheap.

1) Replace the 400Hz generator with a 60HZ unit.
An example of a good unit is:

http://www.northerntool.com/webapp/...uctDisplay?storeId=6970&productId=8795&R=8795

2) Use a motor-generator. Run a 400Hz motor to turn a 60Hz generator (see above).

3) Use a an inverter. You would need to convert the 400Hz to DC then use an electronic inverter to create 60Hz AC.
This would be very expensive as 10KW inverters run ~$5k and this particular one would be very strange. So strange, that you would probably have better luck transforming the 400Hz 240V down to 14VAC then rectifying it to ~12VDC which then runs a standard pair of 5kW inverters ~$2.5k a piece.

Obviously 1) above, should start sounding pretty good about now.


If you are VERY good with electrical engineering practices you could convert the 240V 400Hz into 340VDC DC and make your own inverter that converts this DC back to psuedo 60Hz. This is not for the faint at heart. Dangerous nasty, hard work. Which will surely lead to a few *accidents* most of which will be of the maiming or killing form.

 

[stardelta]

It may be possible to redesign the stator and rotor windings to deliver 60hz then have them both rewound to the new spec` I cant however say with any certainty if this is possible. I would suggest putting the question to the makers of the generator. The AVR will also have to be replaced with an item designed for use at 60hz.

 

[jraef]

And to answer your final part of the question, no, your household appliances cannot work on 400Hz. Anything with a motor would attempt (briefly) to run at 667% speed, but in reality they would just burn up. Incandescant light bulbs may work however, and maybe resistive heating elements such as a water heater, that does not have a circulating fan involved.

"Our virtues and our failings are inseparable, like force and matter. When they separate, man is no more."
Nikola Tesla

 

[mc5w]

Your best bet is to take the alternator off of the engine and then measure the flywheel and alternator coupling. If you go over to Marathon Electric there is a PDF file for SAE engine to generator couplings.

You would then need to select a Marathon 60 Hertz alternator that mechanically matches your engine. An oversize alternator will have better abilty to start and run motors. You would then need to couple the new alternator to the engine.

In your power range Marathon makes 2 different performance grades of 3 phase/ single phase 12 lead alternators. You want the better of the 2 alternators because the lower grade has excessive voltage drop when starting.

You can buy the alternators as 1 bearing and 2 bearing units and a 2 bearing unit would simpler for a refit. The 1 bearing units are intended for factory assembled units that use the engine flywheel to support 1 end of the alternator shaft.

You will also need to adjust the engine governor because 400 Hertz alternators run at either 2,000 RPM or 1,500 RPM. In this size range 2,000 RPM is the most likely candidate.

 

[mc5w]

I have to correct what I wrote. The 1 bearing alternators from Marathon Electric are for direct coupling to an engine. The 2 bearing units are for belt drive or when building a motor generator set.

 

[mc5w]

I have an even better idea. Keep the existing 400 Hertz alternator. Use the output to drive a transformer that supplies a 12 pulse rectifier that charges a 48 volt forklift truck battery. The best configuration would be to use 2 6-pulse bridges in series to produce the 65 volts
DC that you need for charging which eliminates and ineterphase reactor and current balancing. Since this is the only load you could rig the voltage regulator of the 400 Hertz generator to produce the proper DC voltage.

There is also a solar photovoltaic charge regulator on the marker from

http://www.blueskyenergy.com

that can regulate say 80 volts DC down to what is needed to charge a 48 volt battery properly using a 3 stage charging curve. You can equip the battery with a 500 amp shunt that allows the charge controller to both supply load and maintain the right amount of charging current.

You could also belt drive a conventional 10 KW 60 Hertz alternator to the front of the engine. You should be able to get a power takeoff shaft that bolts to the front end of the crankshaft where the harmonic balancer is. You would put your belt sheave onto that. Same power takeoff that is used to drive hydraulic pumps, air compressors, and so forth. Take a peek inside the engine compartment of a ready mix concrete truck to see what I mean. The best belt for this application most likely would be a Goodyear Gripbelt which uses herringbone gears for the sheaves and produces less noise than a conventional toothed timing belt.

What you would do with the whole shebang is to attach an inverter to the 48 volt battery to supply 120/240 volts without the generator when the load is light. When the load is heavy or the battery runs down you crank up the generator. Just make sure that you get an inverter that is rated for solar photovoltaic use so that you can tie in some solar cells.

You can also go over to Bodine Electric and get what are called Transbal electronic ballasts that can run directly off of your 48 volt battery. These are ballasts for places where normal power comes off of a 12, 24, 48, or 120 volt battery. They also have central battery emergency ballasts that are for emergency lighting in telephone central offices.

 

[ScottyUK]

mc5w,

If you are feeding a 6-pulse rectifier with 400Hz 3-phase, the ripple frequency is 1200Hz. If the charger was designed for 60Hz 3-phase and 360Hz ripple frequency, why would you feel the need for a 12-pulse rectifier to push the ripple up to 2400Hz? The magnetic components in the charger would not be intended for this duty and would (i) overheat and (ii) drop more voltage than intended.

The fantasy contraption you describe sounds markedly more expensive than a new 10kW 60Hz generator. I'm pretty sure the OP wants an *economical* means of converting his 400Hz miltary genset to something he can use in the civilian world without involving solar power, FLT batteries, chargers, lighting ballasts for central battery systems... interesting I grant you, but not what he asked for.



----------------------------------

If we learn from our mistakes,
I'm getting a great education!

 

[stardelta]

I agree with Scotty. I have been dropping in and out of this forum for years and have have seen many times simple requests for help or advice met with answers that are of no practical help whatsoever to the person posting the question! Mc5w?? Do you really think that Filbert will have a clue what it is you are talking about and describing,let alone be able to source components and assemble such a thing?? Lets get in the real world and start offering realistic solutions.

 

[SlideRuleEra]

Confirming jraef's posting - incandescent lighting and pure resistance heating devices will work very well on 400 Hz power, without modification. 60 Hz motors will be "toast".

Historical note - In "electro-mechanical days", 400 Hz equipment was used extensively on military aircraft. The higher frequency (compared to 60 Hz) allowed AC equipment (generators, motors, transformers, etc.) to be constructed using much less iron (to obtain the same efficiency). The weight savings were significant. Of course, modern electronics now do those jobs better.

http://www.SlideRuleEra.net

 

[mc5w]

I went over to

http://www.hobartgpu.com

also known as

http://www.aviationgroundequipment.com

and found out that there is a 12 pulse transformer rectifier unit for turning 400 Hertz power into 28.5 volts DC.

The idea behind using both a 60 Hertz alternator and the existing 400 Hertz alternator is to store energy in a battery for use when the load is light. This will save wear and tear on the diesel engine if he has to use it a lot.

If he only needs the diesel generator on an occasional basis then his best bet is to change out the alternator to a 60 Hertz unit and lower the engine speed to 1800 RPM.

There is somebody else at this forum who has an off grid power system that uses a generator, a battery bank, and an inverter so that the generator does not have to run incessantly.