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2deuce
12-05-2006, 07:41
What is it commonly used for? There is a mep21c for sale near me, its 400 hz.
Thanks

emmado22
12-05-2006, 08:38
Radar units. Not much one can do with it...

Boatcarpenter
12-05-2006, 08:52
Lights and around aircraft and radios because it produces less hum than 60 hz I believe.

rmgill
12-05-2006, 09:18
I have a radar set for that if you want. :-) Aircraft used 400 htz too iirc.

ARMYMAN30YearsPlus
12-05-2006, 10:27
When you use AC power the cycles indicate the passing through zero and to the opposite charge. 60 HZ is fine for us humans since we do not detect this on and off and on cycle 60 times a second. The military went to 400 HZ because the time at zero is shorter between cycles and electronics like this smoother AC especially if you are rectifing the AC to DC it produces a smoother pulsed DC current.

rdixiemiller
12-05-2006, 11:51
You can use the 400Hz stuff for incandescent lights. I believe flourescents will digest it as well, and produce less hum and heat. If you are making DC, a 400Hz generator would be nice.

maddawg308
12-05-2006, 11:59
If you are into military radios, there are a lot of aircraft type radio gear that runs on 400hz. You can use it to power your aircraft radios. Ham radio operators that are into the WWII and 1950s-1960s ARC-5, ART-13s, BC-648s, ARC-58s, and other rigs would love to have this genset.

OPCOM
12-06-2006, 01:17
Be careful with old-skool flourescents, monitor the temperature of the ballasts. The electronic balasts may be ok but the inductive ones can be problematic since they have a certain impedance and reactance depending on the power line frequency. The inductance in series with the lamp is to limit the current. At 400Hz, the current may be so much more limited that the emission-heated cathodes or filaments of the lamps will not have enough current to keep them hot. I've used the screw-in flourescent 'light bulbs' (electronically ballasted) on 400Hz and 800Hz for several hundred hours with no ill effects.

The best advantages of 400Hz power are that the transformers and filtering inductors for it are much smaller and lighter in weight than 60Hz counterparts (about 1/3 to 1/6 the volume/weight) and the capacitors used for filtering in power supplies are also requiring much less capacitance and therefore smaller. If for example you need a 1000uF capacitor in a 60Hz application a 150uF unit will do the same for 400Hz.

You can run some transformer-input power supplies on 400Hz at reduced ratings, -monitor the transformer temperature because depending on the constructuion, it may be quicker to heat up or suffer increased core losses (extra heating caused by the more rapid reversal of the polarity). Most switching power supplies will run just fine such as in computers and the like, but in saying this, I assume no responsibility for any 4th of july celebrations.

How much do they want for it?

2deuce
12-06-2006, 02:13
Its in a GSA auction in Salem, Oregon. Bid is $125 at this time.

OPCOM
12-06-2006, 02:22
That's cheap enough! how much power?

Boatcarpenter
12-06-2006, 09:08
Here is the cover for the TM for a MEP-021A I have that someone gave me. Don't know what differences there are between the A and C models.
BC

mangus580
12-06-2006, 09:14
I am pretty sure the A is the points engine, and the C is the electronic ingition engine.

I have a MEP-021... was trying to fire it up last night to power my halogen lamps for splitting some firewood.... Have I mentioned how I hate 'wrap & hope' engines? Yanno where ya wrap the rope, and hope it starts??

The carb on all these small Mil Std engines are a crummy design. Every one I have, wont start if it sits for any time...

Oh well.... I can always dream of a diesel ;-)

ARMYMAN30YearsPlus
12-06-2006, 16:27
Mike that is what Carb cleaner and removeable jets are for aua

G744
12-07-2006, 04:52
400Hz came about for things that fly. Any electric motor or transformer will be an order of magnitude smaller and lighter for 400 than 60 hz.

i.e., a one horse 400HZ motor is about the size of the old quart oil can, and will have a shaft speed of around 5,200 rpm.

As stated before, a lot of mil commo gear has commonality with aircraft radios hence the need for that power freq. Also, it is a lot lighter to pack & haul.

dg

NEIOWA
09-20-2007, 00:09
Assuming good genset but has a 400hz generator. Is it possible (economically) to modify for 60hz output. Rewind the generator or ______? ?

Have a local fire dept that received a pair of nice 60Kw 400hz gensets (MEP115A). My recommendation is to strip out/sell the engines and sent the rest back to sam.

emmado22
09-20-2007, 07:14
Unless you got some 60Hz gennys that have bad motors, the 400Hz's are useless. Get the motors and scrap the rest..

DDoyle
09-20-2007, 09:07
IIRC some, but not all, of the expansible vans are set up for 400 HZ.

David (I wish I was as good as I once was) Doyle

emmado22
09-20-2007, 10:10
All of my 900 series expando vans we used for BDE and BN TOC's were 60Hz..

DDoyle
09-20-2007, 12:28
I am thinking that the 400 hz exapando van may have been the Ford 8x8 expansible van used as battery control for the Pershing missile system.....will add this to the things to refresh my memory about.

DD

NEIOWA
09-20-2007, 16:53
What engine does the MEP115A (or MEP006) have? 6cyl diesel

rmgill
09-20-2007, 22:54
Hmm, i'll have to find out if DC rectifiers can work on 400 Htz. If they can then I can see running a whole house UPS system on it. Charge the batteries with the rectified DC and then use an inverter for the 60htz AC. Hmm, gonna have to call some vendors tomorrow.

OPCOM
09-20-2007, 23:03
Common rectifiers will work fine on 400Hz. There are also solid state converters to make 60Hz from 400Hz. Any large converter should be able to sync up it sphase to the normal power grid 60Hz and make for no glitches at time of transfer.

StrykerPerry
01-23-2016, 17:08
I would like to know how to convert mine also or if they are worth something to someone to sell or trade mine runs great and is in like new condition

papakb
01-24-2016, 00:02
There are a couple of ways to make 60 cycle power from 400 cycle sources but they're expensive and not very practical. Early methods were with "rotary converters" which are all that dynamotors really are. The electronic converters come in 2 flavors, modified sine wave and pure sine wave. Modified sine wave generators are basically square wave generators that product harmonics out the ying yang and therefore shouldn't be used around radios or devices that have transformers in their input circuitry because all of the hash generates lots of useless heat in inductive loads. Pure sine wave converters are much better but are going to cost you if you need much power.

Aircraft love 400 cycle power because transformers, motors, synchros and servos can all be made much smaller and lighter. The Air Force was never concerned with power consumption as much as with weight. The Navy on the other hand didn't care what it weighed as long as you could keep the power consumption down. Onboard ship we had 400 cycle synchros and servos in our radars and after living around them for years I have a dead spot at 400 cycles and no longer hear it.

Kurt
KG6KMJ

Wdr
03-30-2016, 17:50
I was just thinking after reading this thread, if you were wanting to run 3ph motors couldn't you use standard Variable Frequency Drives and supply them off a 400hz gen set? I'm not sure if any of the monitoring circuitry would be affected by 400 vs 60 hz in, I wouldn't think so though, the incoming line is rectified to dc so I would think the 400hz would actually be better? But I know it's recommended to oversize generators feeding VFDs by a large amount because of the harmonics the drive creats, not sure if the 400hz would reduce that.

papakb
04-11-2016, 19:24
400 hz was used in aircraft because transformers took less steel in their cores and therefore were lighter. The same held true of synchros, servos, and motors in general. The flyboys didn't care about how much power things drew since they had all then needed as opposed to the sailors who didn't care what it weighed as long and it didn't eat up too much power. The rule of thumb was never try to run 400hz stuff on 60hz and vice versa. The transformers and inductive loads will heat up and die and ugly death. Light bulbs and resisitive loads don't care what you feed them.

We had a radar with a 22 ton antenna (AN/SPG-49B) that used 400hz stuff because when it was originally designed in the 1950's it was a USAF project. The Navy added gyroscopic stabilization and stuck it on a ship as a part of a missile system so we inherited a lot of 400hz components.
.
rmgill, What radar unit do you have?

There's a lot of very nice Collins radio gear out there that runs on 400hz.

Kurt
KG6KMJ

patracy
04-11-2016, 21:25
I was just thinking after reading this thread, if you were wanting to run 3ph motors couldn't you use standard Variable Frequency Drives and supply them off a 400hz gen set? I'm not sure if any of the monitoring circuitry would be affected by 400 vs 60 hz in, I wouldn't think so though, the incoming line is rectified to dc so I would think the 400hz would actually be better? But I know it's recommended to oversize generators feeding VFDs by a large amount because of the harmonics the drive creats, not sure if the 400hz would reduce that.

Interesting point you bring up. I'm playing with VFD's for a lathe I have. It will take up to 400hz input and output. Stands to reason you could dial it down to 60hz. The problem though is that you're presented with 220v outputs across all 3 legs. Not sure how you'd put that to use.