Air compressor power supply – 200VAC, 400Hz

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Sarvesh Sadana
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Air compressor power supply — 200VAC, 400Hz

Post by Sarvesh Sadana »

This isn't really fusor related, but I was hoping to get some input on this nonetheless.

I recently purchased a 3000 psi air compressor (a Cornelius 130R3500) for a cryocooler I am working on . It was manufactured in the 1960s for use in airplanes. It's in good condition, but the motor requires a 200 volt, 400 hertz 3 phase power supply.
The plug that should go to the power supply. The inside says Bendix 18-11. <br />There is a number on the outside of the plug: MS3106E18-11P.
The plug that should go to the power supply. The inside says Bendix 18-11.
There is a number on the outside of the plug: MS3106E18-11P.
I am thinking of using an aircraft inverter to convert DC power into the required 400Hz, 200VAC. Something like http://www.ebay.com/itm/AIRCRAFT-STATIC ... Swz71ZTqGF or http://www.ebay.com/itm/Collins-US-Mili ... 2059401178

I am unsure, however, about how to connect the inverter to my home's power supply and the compressor plug to the inverter.

Is there an easier way to do this? Or can I simply build my own power supply?

Sarvesh
ian_krase
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Re: Air compressor power supply — 200VAC, 400Hz

Post by ian_krase »

The left-hand one looks like it expects input of 27 volt DC. Possible 24 volt DC would work and there are lots of cheap 24 volt supplies. However, it only puts out 36 volts of AC.

The right-hand one has no data available on the Ebay page.

If you can find a datasheet it will tell you.


It might be possible to use a VFD, normally used for varying the speed of 3 phase motors.
John Myers
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Re: Air compressor power supply — 200VAC, 400Hz

Post by John Myers »

I would use a VFD and a 27V supply.
The second ebay item doesn't do what you need.
For about the price of the first ebay item you can get an VFD, which means you can plug it into the wall and get a 400hz 200v output. Otherwise you would still need to convert 120V AC to 27V DC, and I doubt a cheap 24V brick can supply enough current.
Jerry Biehler
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Jerry Biehler »

Yup, just get a VFD, The Hitachi SJ200 are good units and will do up to 400Hz. You can set the output voltage in the parameters. You just need to figure out phase rotation. You can set the VFD to run at a few hertz to make sure it is pumping the right way before bringing it up to full speed. You can get versions of the VFD that are 120v or 240 input to suit whatever line voltage you are working with.

Those units on ebay are useless for what you want to do. Only 36v out and I really doubt designed to run a highly inductive load like a motor.

The connector is a pretty generic MS connector, you should be able to get a mate off ebay, a new one with the backshell will probably be about $60. They are standardized among the brands, amphenol, bendix, and a couple japanese brands.
Sarvesh Sadana
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Sarvesh Sadana »

Very interesting. The reason I was looking at the second unit is that someone had used it before to power the same type of compressor. http://www.ebay.com/itm/Cornelius-Compr ... 1438888206

I'll definitely take a look at a suitable VFD. Most of them seem to operate at an input of 220V, which is another problem.

I'm going to try to disassemble a few of the parts so I can get a good look at the plate on the motor, which may tell me the phase rotation and other info.

Sarvesh
Jerry Biehler
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Jerry Biehler »

Automation Direct sells a 120v in 240v out drive: https://www.automationdirect.com/adc/Sh ... -_575_VAC)

You probably dont need more than 1/4hp but I would get one of the larger ones just to have the extra capacity.

Looks like that Collins unit outputs 115v 3 phase which is a good way to burn out the motor ran if ran long term if the motor is really rated for 200v.
Jim Stead
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Jim Stead »

I didn't have any luck with that link. Here's another: https://www.automationdirect.com/adc/Sh ... -_575_VAC)
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Rich Feldman
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Rich Feldman »

>> I'll definitely take a look at a suitable VFD. Most of them seem to operate at an input of 220V, which is another problem.

Yes, VFD's need extra stuff if their output voltage is to be higher than their AC input voltage.

I live across the Bay from you, and can give you a 120 to 240 volt transformer. The cord, outlet, switch, and fuse might be left as exercises for the taker. First step: you need to provide the 400 Hz motor's power rating and/or the single phase current that your VFD will need.
All models are wrong; some models are useful. -- George Box
Sarvesh Sadana
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Sarvesh Sadana »

It appears the motor information plate was covered in some sort of tape, many years ago. It was in a horribly awkward place, and I would have had to disassemble the entire compressor to get at it. It took a few hours, but I finally managed to scrape it most of it off and read it with a magnifying glass.

Aircraft AC Motor

200 Volts
7-8 Amps
3 Phase
11500 RPM
Continuous duty
Serial number (Best guess): WH 3685
MFR's Part No. (Best guess): A46A6406-3
90 OZ-FT
60 P.F. (See pic)
I don't know what P.F. stands for. Power factor cannot be greater than 1.
I don't know what P.F. stands for. Power factor cannot be greater than 1.
It appears that the VFDs with 115v input cannot supply the required amperage. I'll have to use a step up transformer to connect to a higher voltage VFD. Rich, that's a very generous offer and I'd love to take you up on it. I'll PM you.

I do have a few questions regarding the operation of the linked units, though. They appear to have ethernet ports. Would I need some sort of controller for it? Also, what sort of adaptor would I need to connect my compressor to the screw terminals on the VFD?

I really appreciate all of the help you've given me

Sarvesh
ian_krase
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Re: Air compressor power supply — 200VAC, 400Hz

Post by ian_krase »

There is really no guarantee that a port that looks like Ethernet is Ethernet, and best not to try plugging into a computer you care about if you don't know.

If they are indeed Ethernet, they might be a wierd industrial/control protocol like EtherNet/IP (not the same thing as just normal Internet Protocol over an Ethernet LAN) or Profinet. Can you take pictures of the whole unit?

As to the connector, you're looking at hunting down a mating connector and doing the terminal block /cable harness thing yourself.
Jerry Biehler
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Jerry Biehler »

Dang, 7-8 amps. So you are going to need a 3HP vfd which just dont come in 120v input.

I recommend something like this: https://www.driveswarehouse.com/wj200-022lf-2533

I have installed a LOT of VFDs, FWIW.

Its getting to be a decent amount of money spent on this thing, you might want to find someone that has 208 3 phase and hook it up to that first, it will run at proportionally lower speed but at least you will know it works before dumping money into a VFD you cant return.
ian_krase
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Re: Air compressor power supply — 200VAC, 400Hz

Post by ian_krase »

At this rate it's sounding like it's not impossible that you might want a change of motors. Though of course the power requirements are not going away.
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Rich Feldman
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Rich Feldman »

>> you might want a change of motors.

From the voltage and current, the motor behind Sarvesh's nameplate picture is around 2.5 horsepower. (could work it out from the RPM and torque values). A 60 Hz motor of similar power would be much bigger, and not turn anywhere close to 12000 RPM.

Here's a contemporary motor made for 400 Hz 200 V 3-phase. 4.5 horsepower continuous duty, length 8.8 inches, weight 14 lbs.
me421asc.jpg
me421asc.jpg (14.45 KiB) Viewed 7902 times
from http://www.400hertz.net/Products/ME-421SC.htm. Nice FAQ at http://400hertz.net/faqs.htm#1

I like Jerry's idea of firing up the unit on 60 Hz 208 V 3-phase. The compressor's flow would be reduced by a ratio similar to the power frequency ratio, but I will guess that its max pressure won't take a huge hit. The office cubicle wiring at my day job is based on 208 V 3-phase; each 120 V receptacle is connected to one phase and neutral.
All models are wrong; some models are useful. -- George Box
Sarvesh Sadana
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Sarvesh Sadana »

You're right Ian, according to the pictures, they seem to require an RJ12 connector.

I don't think it would be very possible to change the motor. It is currently at the heart of the machine and it would be almost impossible to remove, not to mention the fact that a compatible motor would be very difficult to find.

Here are more pictures of the machine, as you requested. (For some reason, they are sideways. Click on it and it appears normally)
The motor. As you can see, it is too deep inside to be easily removed.
The motor. As you can see, it is too deep inside to be easily removed.
The compressor itself
The compressor itself
The operating instructions
The operating instructions
According to this, there is a secondary DC circuit. I believe it runs on 27.5 volt DC at 4 amps and purges the oil.
According to this, there is a secondary DC circuit. I believe it runs on 27.5 volt DC at 4 amps and purges the oil.
I can try to hook it up to a 60hz 208v socket, but I still don't have the connector required to do so. Would something like https://www.digikey.com/product-detail/ ... ND/2449325 work? (http://www.mouser.com/ProductDetail/Amp ... JWxw%3D%3D has the same part number and is cheaper, but for some reason the picture is different.)

Also, I found the same model (WJ200-022LF) used on ebay with 30 day return and a warranty for cheaper. http://www.ebay.com/itm/HITACHI-WJ200-0 ... SwrfVZSUhs

Sarvesh
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Re: Air compressor power supply — 200VAC, 400Hz

Post by John Myers »

The pictures for both digi-key a Mouser sometimes don't match the actually part number exactly (which they warn you about somewhere), the pictures just give you a general idea of what it looks like.

You could just re-terminate the cable with a non Mil spec and less expensive connector.
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Rich Feldman
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Rich Feldman »

That particular VFD model (WJ200-022LF), according to the ebay listing as well as Jerry's link (driveswarehouse), needs 3-phase AC input. So you could use it as a frequency converter but not a phase converter. Jerry's experience, or maybe the product user's guide (linked at DW) might describe qualified exceptions to that.

You can't turn house power (single phase) into three-phase with just transformers.

John suggested cutting the plug off and substituting a less expensive connector. If you want to sort of follow a standard, the three-phase five-wire path seems to lead to NEMA L21 types.
170px-L21-30_plug_and_receptacle.jpg
170px-L21-30_plug_and_receptacle.jpg (5.1 KiB) Viewed 7845 times
No straight blade/pin, only twist-and-lock variants. See also http://www.stayonline.com/nema-l21-20-l ... cords.aspx. On Monday I can see which kind are used in our labs, and on our Bridgeport. I have no idea what NEMA says about 400 Hz. That 400hertz.com company sells 200 V electric tools (with neither brushes nor semiconductors) and support equipment for jobs like concrete sawing. How about if you find out what connector convention they follow?

If the compressor and its weird plug with five round pins were mine, I would put single pin receptacle contacts on five insulated wires of appropriate thickness. Each would be individually insulated with heat-shrink tubing, maybe even 2 layers, then mated to the corresponding pin of the compressor plug. Finished off with some kind of strain relief, like splinting the connection with a broomstick and some duct tape.
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Jerry Biehler »

The VFD will run just fine on single phase. They dont care, its not until you get to the big VFDs that they start looking for phase loss.

Yes, those connectors look like the mates to what you have on the pump.

You dont want to change the motor, it is not going to be a standard frame mount and is probably splined. It would be a nightmare.

Running the motor on 60 just means it will pump slower, it will still reach the same pressure since the frequency is what determines the motor speed.

You really need to pop open the control box and see what is going on in there before you do anything. I am guessing it uses the 28v in for the control circuit and any overpressure kickoff.
Sarvesh Sadana
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Sarvesh Sadana »

Even though it can run on single phase power, would it not be preferable to use one designed for it, such as https://www.driveswarehouse.com/nes1-022sb-2692 or https://www.driveswarehouse.com/ode-3-2 ... r-invertek?

I think I will simply try to follow the wiring diagram on the VFD I purchase rather than try my hand at connecting it to a different plug. I will still need a transformer to get it to the 200 volt input power.

I'll also try to find any more information on the accessory DC circuit. I'm hoping it's not crucial to the operation of the compressor. I do have a lab supply that I can use for it, though.

Sarvesh
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Rich Feldman
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Rich Feldman »

I think John and I were referring to the 400 Hz connector, not the connector between VFD and the wall. Parametric search tools on distributor websites just taught me a lot about "18-11" or "18, 11" MIL/Aero circular connectors. Stumbled upon one good deal at Allied Electronics, and it even has a picture with correct number of pins. :-)
round_one.PNG
Even when not "on sale", it looks like this sort of connector is in the same price ballpark as NEMA plugs and sockets when you get into three-phase.

Re. single phase input to VFD, I knew it generally works, and the connection drawing often says which two of the three terminals to use. So it was a surprise to see "three phase only" in the product description. Jerry, and/or the product documentation, can explain how to compute the two-wire input current and derate the output current if necessary. (I'm thinking about ripple current in bus capacitors, PFC circuit operation, etc.)
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Re: Air compressor power supply — 200VAC, 400Hz

Post by Jerry Biehler »

Modern VFDs do not need to be derated, old ones did but new ones just dont care, at least at this size of VFD. When you get to 10HP plus then you might start worrying about derating. Worst case scenarios is you get a under voltage alarm on the buss, but with running the motor at 200v that will be just about impossible.

Really, you can get just about any 3 hp 240v rated VFD and run with it, I would just not buy anything chinese. Oh, and make sure it actually does 400hz, some drives top out at 360.

I use mitsubishi servos on my cnc mill and lathe and they are intended for three phase and I have never had an issue, and the spindle motor on my lathe is a 5kw servo. The servo drives are basically a VFD but 3 times more complicated.

You REALLY need to open the control box and see whats going on, my guess is it wont work without aux DC.
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