Certainly the low price leader at this point…
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I appreciate the response. I wish it made more sense.
I can get behind “Siemens only”, but you loose me at “drop out”, and suggesting that the motor will “draw too much heat” conflicts with my understanding of electrickery.
Object of the game is to swing this thing as hard as possible, so “drop out” does not sound like what I’m after.
I’d also prefer not to oversize if possible, as all this requires is appropriate sized wires on the front side of the magic, I’m going to keep looking for 5HP options that are rated for single phase input.
Hopefully ABB or Yaskawa has something similar to the gohz unit linked above.
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The shortest explanation I can give to explain @spdking 's point is that vfd’s actually convert AC to DC then use pulse width modulation to output a series of DC pulses that approximates a sign wave. Some brands do a much better job of doing this than others. Lower quality drives typically do a worse job at approximating a sine wave . All of the “noise” outside of a true sign wave generates heat. Typically the quality of the sine wave is worse at lower frequencies because the dc bus voltage runs at roughly 1.4× line voltage and the lower the frequency, the lower the output voltage needs to be. Therefore the lower the frequency, the shorter the pulse. At 30hz the motor requires half the voltage as at 60hz to produce the same amount of torque. If you were to provide the same voltage at 30hz as 60hz the amperage traveling through the windings would double and burn up the motor.
Some 400v class drives can be used on a 200v class motor. This is can be accomplished if you can set the base frequency of the 400v drive to 120hz. Then at 60hz it’s putting out 200v . This is commonly done on woodworking equipment like routers to maintain hp at higher frequencies.
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knew that at one point…but had not seen the connection to @spdking’s explanation. the rest of your translation also makes wonderful sense. thank you!
got any thoughts on the GoHz solution? http://www.gohz.com/5hp-vfd
or do you recommend I call Siemens and ask for their solution?
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To elaborate on your specific situation…very few 400v class drives will run acting as a phase converter. I have never heard of one in my years of automation but have never looked for one either because I have never encountered 400v single phase.
Your ideal vfd is a 10+hp 200v class that accepts a single phase input. If I personally had the exact situation you do, where it appears your goal is to speed up (60hz+) I would run an automation direct gs4. If the goal were to run sub 60hz I would go with a more robust option like siemens. If it were a customers it would automatically get siemens or abb. (I have multiple automation direct plc’s and drives on my personal equipment with no issues ever)
You can not just go by HP and voltage, the actual limiting factor on the drive itself is amperage. A 400v 10hp drive is rated at roughly 15 amps nominal. A 200v 5hp drive is also 15 amps nominal.
If placing the vfd in an explosion proof cabinet I would oversize it even further. Vfd’s produce a lot of heat that isn’t dissipated well in a sealed cabinet. You would be better off remote mounting the vfd in a non hazardous location with adequate ventilation. Typically your EE sizes the conductors going to your vfd to your motor not the max capacity of the drive. It’s not uncommon to see vfd’s derated to 50% or less due to operating environment.
I’ve played with a couple of generic chinese copy drives like the gohz. The biggest issue I have found is a lack of documentation, it’s pretty hard to control one via plc or pc without documentation of what commands need to be sent to which address. If you were to go that route make sure you can control it with your current control system. I would also not trust the rating and go at least one size higher than what they recommend.
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On a rotary phase converter, the HP they are referring to is that of the size of the “idler” motor, not the size of the load capable of being driven off it, which is usually about half the size of the idler. RPC’s “wild leg” or “generated leg” is usually not advised to run control circuitry off of but will start and run a motor load just fine if it’s balanced correctly.
Before I knew what I now know about VFD’s and started using them on my equipment I had built and ran a couple of different RPC’s, biggest one was about 40 HP.
Feel free to PM me if you need some guidance. There are certainly much cheaper options out there than buying a premade RPC especially when you factor freight on a heavy idler motor. There’s a couple of sellers on eBay that just sell the panels with far more reasonable shipping, IMO much easier and cheaper to source a good size motor locally from a surplus shop or Craigslist.
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ABB tech said “all their drives” will do this, but “some will need to be derated”. I assumed that meant most drives could be configured that way.
yeah, I can get 400V DC out of my car, but I’ve not seen 480V single phase dangling from the wall anywhere. I’ve gone looking for 480V 3-phase on more than one occasion, and had to find 600V for a fuge a week or two back…
the concept that I can set the base frequency to 120hz to get 240V out of a drive wired to 480V is an eye-opener, and implies that I had other options than a boost transformer to run that 600V fuge.
even noticed “kits” for building those panels. yeah boat anchors do seem to be relatively abundant, at least in the circles I travel. 
thank you!!
I suspect I’m going to take @emdub27’s advice on this one.
Although I prefer to salvage or build when I can.
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I noticed that some drives allow you to change the pulse frequency.
assuming that higher frequency switching leads to “cleaner” sine waves, why would I not turn an ABB from it’s stock 4khz to 16khz every time?
In practice with a quality drive like abb there is little to no noticeable gain to be had by increasing the pulse frequency in the area we use vfd’s. I ussually don’t start tweaking pulse frequency unless we are going above 120hz. 16khz is generally used for 400hz equipment like routers.
Yes, we could make a 400v class vfd output 600v at 60hz. 600v is about the most you can get out of a 400v class drive. If you set the base voltage to 480v, then set the base frequency to about 48hz you would get 600v at 60hz with a linear voltage curve programmed. Torque would fall off rapidly if you went above 68hz in that scenario. Also, not all drives allow you to set any base frequency, some only allow 50hz or 60hz.
Make sure abb knows you are trying to power a 400v class drive with roughly 230v single phase, then go to a 5hp 230v motor. I’ve never tried to use 230v input on a 400v drive, let alone 230v single phase, but a lot of things can be accomplished if you can program the drive effectively. The most output voltage you would get with 230v input would be roughly 340v.
Also for anyone reading this thread that may not be aware, when I say 400v class drive, that means a drive that operates anywhere from 380v to 480v base voltage. This is to accommodate the different grids encountered around the world.
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If you use bare.min it will get hot and wear out. Upgrade to a larger vfd. It won’t get as hot and it will last longer.
Yes you want to “drop out” the freq. Of you do not and end up dropping like voltage and amps you will damage the motor almost immediately. You want to “cut th freq” out of the signal and only allow volts and amps to stay the same. If you use a cheap vfd and drop the volts and amps you’ll end up burning it up fast. So yes. You want a vfd that can drop out the freq not power load.
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That all depends on the full load amperage, people like to double the number to be safe. You could probably get away with running a 18 amp moter with a 20 FLA vfd. In the event of stalling the motor you can burn the drive up, that is why the FLA raiting is usually overkill.
My advice, call the company who provided you with the components and ask for a suitable vfd.
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you use strange words sir.
“modulating the DC pulse width” and “drop out the frequency” may mean the same in your whirled, but your wording does not convey the concept in a manner that can be searched on the web.
motors don’t “draw heat”…they draw current, which if supplied indiscriminately or in the wrong manner can generate heat. does that make your explanation wrong? nope, but it does make it fairly difficult to interpret.
@emdub27 was kind enough to translate…
Edit: if you’d used “chop the frequency” we would have been on the same page…
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That is where I started…
This is a similar sized fuge with the same motor, from the same supplier.
I’m running it in his shop with the only VFD he had that day. This is TOP speed with the drive we had available…
He reckons the drive I’ve got will get us down the road a ways. Given my intended use, I’m looking at my other options…
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If you gotta run it it will work, it is just not ideal. If it fails at least you probably already know the mode it failed in. 
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Drop out voltage on a vfd is any time the drive cannot effectively make the required voltage for the current demand. When it happens there are weird transient spikes in voltages that burn out the insulation in the wire, motor or both.
You do have to be careful with correctly setting up the limits of the drive. Particularly the current limits. If you don’t set those correctly it is entirely possible to send 10x the nameplate amperage of the motor and burn it up immediately.
In a standard off the shelf drive the output voltage maintains a linear relationship with the output frequency. 115v at 30hz, 230v at 60hz above 60hz can vary if you program the drive for constant horsepower or constant torque. If you were to apply the same voltage at 30hz as 60hzthe current would double and burn up the motor. Again, closely monitor the amperage the vfd puts out via its screen and keep it below the nameplate amperage of the motor and you will be good. Don’t trust clamp meters on vfd’s unless you have a nice Fluke or Fieldpiece or similar meter. A standard clamp meter will always read low.
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@cyclopath in your situation, an effectively 2hp drive on a 5hp motor, I would set the current limits to no more than 80% of what the drive is capable. Drives do not like to be run flat out at 100% rated current for long periods. If run at 100% it will be hot and heat just compounds the problems. Your 5hp motor could live a long happy life at 2hp. You just won’t be able to spin it as fast as if it had a 5hp drive.
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Again, Thank you!!
Yeah, spinning the 5HP motor with a 1/2hp drive was an interesting game. Took us a bit to find a spot where the rotor moved and the drive didn’t fault.
Without the solvent in there we could get it moving considerably faster, as the solvent cooled towards -50C and the viscosity increased, so did the load on the drive. I believe I gave up before the drive did.
“Running” with a 2HP drive is clearly possible…if it’s appropriately limited, but who wants a centrifuge without a “ludicrous” setting? 
Edit: this one won’t be going plaid, but @Lincoln20XX promised video when he takes the device it’s replacing into that vicinity
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Or, um, “vary the frequency”
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As in Variable Frequency Drive?
I test fitted “vary” as a substitute for “drop out” the frequency…
But a VFD that I could vary the frequency only down on didn’t compute.
“Chop” I get.