Uses for 400hz generator?

[OPCOM]

60 or 400Hz as long as it can be discussed civilly. yeah, not directly an auction post but it is close enough. No harm done. It's important that people know the difference between the uses of 60Hz and 400Hz generators. Thanks.

 

[saddamsnightmare]

February 10th, 2010.

Correct me if I'm wrong here, but I do believe that a 400 HZ output generator could be used to drive a high resistance load, as in the form of heating elements. If I am correct, an MEP023A or equivalent unit delivers about 13 HP or 10KW worth of heat equivalent output. One could run a special set of resistance heat units, either baseboard (preferred) or in the furnace plenum uptake to heat the house in an emergency. The problem is one would need to locate a 400 HZ motor to drive the blower through separate controls from the normal house system. Converting the unit with an MEP17A generator head (60HZ) would work as the manuals treat them as interchangeable units except for the HZ outputs, or one could graft a new civillian head (60HZ) to the unit. Costs might not be so prohibitive, as most civillian unit engines are not designed for the high load continuous duty cycles that the military units were designed for, hence the weight difference between a 10KW civillian unit and a 10 KW military unit.
An MEP023A weighs in at around 650 Lbs, the equivalent output civillian ones weigh a little more then half that in operable condition. As in locomotives, the heaver the generator system the better they can stand heavier loads proportionately. Just a guess, as it were... As a footnote, a specially designed extra heavy duty 30KW diesel unit back in 1985 ran about $10,000 new, I suspect they would be much higher now (not chinese made, either, but a German supplied special Deutz FL-912-4 engine was used, as the unit had to be able to operate from the Arctic to the equator).

Cheers,

Kyle F. McGrogan

 

[OPCOM]

I think you are right. 400Hz is perfectly fine for resistive loads such as light bulbs and electric heaters. It is also OK for most things that come right off the line to a rectifier and a capacitor bank, which until recently included most switching power supplies. Now most of them use a PFC (power factor controller) front end that follows the 60Hz wave and adjusts the duty cycle of a switch device so that the power supply appears to be a resistive load instead of a reactive (capacitive) load. Good for the efficiency and the power company, and a 60Hz generator. It's uncertain an individual PFC-based switcher would react to a 400Hz waveform. An exciting experiment.

There are from time to time frequency converters available, that can take in a range of frequencies and make a 60Hz output. The simplest is a motor-generator, about 65% efficient at best. Then there are solid state ones $$.

I have run 60Hz linear-regulator-type power supplies on 400Hz. The efficiency and capacity is lowered, and the transformer can get pretty hot with any decent load on the supply. Maybe finding a "useless" 400Hz power supply that takes 120V 400Hz in, and makes 12 or 24 volts DC output, and then connecting it to a 12V or 24V to 120VAC 60Hz inverter is a possibility for running a motor. What about high starting current?

In my work I recently was sent a motor to disassemble snd investigate. It is an AC motor. The motor itself is a 3-phase winding and a magnetized rotor. 1/3HP variable speed motor for a furnace. The input is 120VAC, goes right to a bank of rectifiers. The speed of the motor is controlled by a PWM signal from the furnace's controller. So, all roational speed comes from a little signal rather than the line having to be 60Hz. One thing to note - -in most furnaces there are also 60Hz control transformers to deal with the thermostat, as well as a 24V 60Hz contactor to control the motor. some have a circuit board as well.

In the end, maybe a set of 15-amp extension cords and (motorless) radiant heaters in the rooms is an idea.

 

[Keith_J]

High power inverter will be about 90% efficient. If the 400 Hz unit is 3 phase, a delta-wye bridge rectifier would produce DC with very little ripple. And you wouldn't need any boost section on the inverter either, increasing the efficiency.

This is becoming more common in long distance power transmission where high voltage AC is rectified for long distances. At the other end, phase is determined by the inverter. These are called HV DC ties. This is done to alleviate power factor issues.

 

[armytruck63]

One thing a 400 Hz generator could be used for, with no modifications, is running incandescent lights.

Incandescent lights operate fine on DC or AC volts regardless of frequency, as long as the voltage is correct.

 

[Verkstad]

Would 400Hz work for universal (AC or DC) motors too?
Not that I really care, But it may be an interesting thought.

Jakob

 

[drdstny]

Forgive me for not reading the entire folly.

400Hz gensets are for a group of 400Hz gear that spends its time in the field. I'll leav it at that for simplicity and OpSec.

If you have one of these generators and you want to find a way to use it at home / shop, you are significantly limited. Here are the few things that are relevant to civilian ownership those generators will drive:

--Lights. Big, honkin, telescopic-mast mercury vapor or halide lights.
--Welders, *IF* you clamp the voltage with a pair of 200Hz conditioners, you have 2 channels of 3-phase 60Hz, but it is very very VERY dirty power, like such that I hope you're using flux-core wire because it'll be hit or miss in your bead.
--Heaters. There are some low-VOC heaters out there that are really just big dumb electric ribbon heaters and it just so happens they're 400Hz. They're also 6' long and weigh about 200#, so if you're going to put one up, exercise by crucifying your sister-in-law. Repeatedly.
--Battery bank for a UPS system. DC doesn't care about Hz, but you need enough batteries to accept the output without popping every time you fire it up.
--Traffic signs (don't know why you'd have this at home, but OK)

Basically, lights and heaters. You will get way more use and reliability out of them for the small price you paid for the generator. Making them "step down" to 60Hz is, sorry to use the term, a fool's errand. Finding stuff that'll work on the generator will be easier and cheaper than trying to make the generator do your bidding.

And don't put too much effort into it. We've all jumped the gun on an auction without reading the fine print, it's no big deal if you walk away from it before it becomes an issue at home.

 

[TIGERFANS2]

We've all jumped the gun on an auction without reading the fine print

speak for yourself......

 

[acesneights1]

Great thread. I almost...Jumped the Gun until I read this. There are two going up for grabs in Ma right now.

 

[ETN550]

Sometimes the 400 hz units are in really really nice condition. If so and if a very poor condition 60 hz unit can be found for, say $250 - $350 then a conversion is practical if hobby time does not count. The remains of the doner unit can probably be parted out for more than the doner cost and the removed 400hz end will light up the scrap man's eyes due to copper content.

I believe, if knowledge and tools are present and time is not the issue that the overall result can be a 60hz generator in Excellent condition for below market value after sale and scrap of the doner. Along the way one will learn intimately how the unit works which is worth a lot of peace of mind when it is called to duty.

The next best option is to find someone else who will bite on the conversion option and sell 400hz and doner 60hz to come out even.

I agree keeping a 400hz as is or trying to condition the output is wasted time and money.

 

[Isaac-1]

Just to add to ETN550's comment, some of these smaller (under about 10-15KW) 400 hz units can be a great source for parts for their 60 Hz cousins. I recently saw some 0 hour 400 hz units listed on GL that I would have been tempted to bid on if the price were right and if they were a thousand miles closer, appeared to be true 0 hour, complete with aux fuel kit, grounding kit, etc.

Ike

 

[simpleserf]

Given that there are those of us who follow GL auctions, It can be possible to find 400hz transformers. Take one of these, Order some bridge Rectifiers online, and you can charge a BIG battery bank.

Also, in industry, VFD's can be used to adjust input, you just have to know about the various electronics used. Old ABB drives are sometimes free for the hauling. Might be able to use one of these to get whatever freq you want out of it . Just watch out for the HV DC inside!!!!

Also good parts units!

 

[JamesSullivan]

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