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How to Best Convert 400 Hz to 60 Hz

01/28/2009 1:28 PM

I have a Hobart generator that I would like to use at a mine site to run some of the equipment. It is a 3 phase, 90 KVA, 72 KW generator using a John Deere engine. It was used by an airline to service their plans on the ground.

Any suggestions would be appreciated.

David

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Pathfinder Tags: 400 HZ to 60 HZ
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#1

Re: How to Best Convert 400 Hz to 60 Hz

01/28/2009 4:25 PM

You need to find the schematic for it and rewire the generator. ie start paralleling some poles. Kind of a nightmare, but if you like to ride horses there you go.

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#4
In reply to #1

Re: How to Best Convert 400 Hz to 60 Hz

01/28/2009 11:26 PM

Good comment, it appears I need an experianced electrition on this task.

Thanks,

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#2

Re: How to Best Convert 400 Hz to 60 Hz

01/28/2009 8:29 PM

AZ,

Off the shelf 400Hz. to 60HZ. converters are available at the link.

Best of Luck!

Rock1

http://www.elect-spec.com/freqchgr_a.htm#F

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#3
In reply to #2

Re: How to Best Convert 400 Hz to 60 Hz

01/28/2009 9:33 PM

I was going to ask for a rectifier converter search- but you already mede me redundant GA

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#5
In reply to #2

Re: How to Best Convert 400 Hz to 60 Hz

01/28/2009 11:36 PM

I appreciate the link and easy solution, however I have been told that all I need is some type of rheostat. I do need to solve this and will do so. However, I would like to also do it as economically as possible.

Thanks for the input,

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#7
In reply to #5

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 2:15 AM

By a rheostat, you can change voltage (and that too at the cost of a huge power loss, tremondous amount of power is going to be eaten up by it.

For stepping down of voltage the transformer or a SCR control is always a better and efficient solution.

You have been misguided.

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#15
In reply to #7

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 10:26 AM

Thank you for the clarification.

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#14
In reply to #5

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 10:25 AM

If the rheostat can be used to somehow control the speed of the John Deere engine they may be right.

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#9
In reply to #2

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 3:53 AM

Those are very small conferters...

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#6

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 12:29 AM

AZ; NO WAY WILL THIS RUN 60 HZ EQUIPMENT, YOU CANT REWIRE THE GENERATOR, THE BEST WOULD BE TO HAVE THE GENERATOR REWOUND BUT IT WOULD NOT BE THE SAME KVA THE OTHER WOULD BE RECTIFIER THE OUT & FEED IT TO A VARIBLE FREQ DRIVE TO GIVE YOU 0 TO 120 HERTZ OUTPUT PERRY

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#16
In reply to #6

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 11:22 AM

Thanks for the input.

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#8

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 3:52 AM

If you can acquire a 90-100 kVA 60 Hz UPS you can use it as a frequency converter. You have to disconnect the original mains input (in order to have the chopper run) and supply the rectifier directly. (Maybe you will need to change the rectifier diodes to faster ones.) You can control the frequency and the voltage with the original output controls of the UPS. The efficiency will be about 80-85 %.

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#17
In reply to #8

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 11:23 AM

Thanks, I'm most certainly getting a leason here.

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#19
In reply to #17

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 11:29 AM

You should take a leason lesson in using the spell checker every time you post!

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#10

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 7:05 AM

Sell this generator (look on ebay to see what it might be worth!), I am sure that it is quite valuable to someone in the aircraft industry, just as it is. With the money made go and buy a proper 110volt 60hz generator....

Don't waste money on converters, nor is it an easy job to rewire it as part of the reason for the frequency, is the RPM of the motor driving it. You would need to slow the drive motor down as well as rewire.....big job.

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#11
In reply to #10

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 7:56 AM

Hi Andy,

I appreciate your wise advice . Why to complicate the issue.Simple solution to a non electrical person who cannot understand difference between voltage and frequency leave alone conversion.

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#12
In reply to #11

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 8:15 AM

You got it!!!

Have a great day!!

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#18
In reply to #10

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 11:25 AM

Thanks, this may be the wisest way to handle.

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#13

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 10:17 AM

We once had a need to convert the frequency from 60 HZ to 50 HZ. The way we accomplished this was to run a motor @ 60 HZ and then had a belt and pulley arrangement going to a generator. The generator then produced power @ 50 HZ. We had taps for 220 V 3 phase and single phase on the transformer powered by the generator. Maybe something like this would be useful for you? Admittedly the ratio is much different but through mechanical means and different pulley sizes it should be possible. I guess the biggest problem for you would be coming up with the 400 HZ motor large enough to provide the power to the second generator.

One stupid question though... would it be possible to slow down the John Deere engine to where the generator was only putting out 50 HZ?

To me, this would be the cheapest providing you didn't need to buy something to slow the engine down.

One more... would it be possible to slow down the speed of the generator through gearing it down?

To me, this would be the simplest while using a minimum of new equipment.

I don't know if the generator would handle your power requirements at the lower speed though.

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#20
In reply to #13

Re: How to Best Convert 400 Hz to 60 Hz

01/29/2009 11:32 AM

Interesting, it seems logical. I will see if it can be slowed and what the possible consequences might be.

Thanks for taking the time.

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#21
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Re: How to Best Convert 400 Hz to 60 Hz

01/30/2009 10:39 AM

My pleasure.

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#23
In reply to #20

Re: How to Best Convert 400 Hz to 60 Hz

01/30/2009 5:39 PM

The consequences will be a mess.....you need to slow it down by a ratio of 1:6.67

If it runs at 2000 rpm now, you will need to run it at about 300 rpm!!!!

Even if you achieve that, the power output will be almost "zer0"........

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#24
In reply to #13

Re: How to Best Convert 400 Hz to 60 Hz

01/31/2009 10:38 PM

Interesting, logical but may not be practical.

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#22

Re: How to Best Convert 400 Hz to 60 Hz

01/30/2009 1:10 PM

If you slow it down, then of course the frequency will go down, also will the output power of the generator.

Also the magnetic circuit will be designed for a particular frequency, that too will be affected.

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#25
In reply to #22

Re: How to Best Convert 400 Hz to 60 Hz

01/31/2009 10:40 PM

Got it, thanks

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#26

Re: How to Best Convert 400 Hz to 60 Hz

02/01/2009 5:20 PM

Higher freqs need smaller iron parts for motors, generators, tranformers, etc.

I may be wrong but your generator rewired for 60, if possible, may need to be greatly derated to maked up for the lack of "core".

I'd check for some kind of electrical converter. Solid state stuff is getting chearper all
the time

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#27

Re: How to Best Convert 400 Hz to 60 Hz

02/01/2009 5:43 PM

On second thought;

Throw away the alternator/regulator. Go find a used one of the right specs. install. adjust.

probably far and away the cheapest practical way.

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#28
In reply to #27

Re: How to Best Convert 400 Hz to 60 Hz

02/01/2009 8:27 PM

Is it the alternator/regulator that creats the Hz and replacing it could work?

Thanks

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#29
In reply to #28

Re: How to Best Convert 400 Hz to 60 Hz

02/02/2009 3:37 AM

The HZ is a product of the number of poles and the speed of the prime mover....

From memory only (dangerous!):-

HZ = (Number of poles/2)xRPM (for a single phase alternator)

The " /2" may not be correct......it might just be poles x RPM.

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#30
In reply to #29

Re: How to Best Convert 400 Hz to 60 Hz

02/02/2009 11:42 PM

Thanks Andy, another good lesson (sometimes we learn)

You are the consummate teacher.

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#31
In reply to #30

Re: How to Best Convert 400 Hz to 60 Hz

02/03/2009 1:41 AM

I was taught (well I feel) in the RN during the cold war in the early 60's. We could repair just about anything on a ship while still on the move......it has stood me in good stead since then.

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#32

Re: How to Best Convert 400 Hz to 60 Hz

03/27/2009 11:33 AM

I have the same unit, excess airline surplus. 90kva 72kw 3 phase 400hz, driven by cummins st 6 5.9 ltr diesel. I am sure there is a way to acomplish this task but with the advent of solid state tech, it will not be as easy at a pot adjustment. I plan to use this unit to power farming water pumps as well as my shop. I cant wait to get rid of the 200 ft extension cord from the house.

Brgd's Dave

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Andy Germany (6); Anonymous Poster (3); AZ Miner (11); Keywalker (3); mayt2u (1); perry (1); Qqberci (2); Rock1 (1); sb (3); V.I.Abraham (1)

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