3 phase VFD with single phase input

[Robert Murphy]

Does anybody have any experience with a setup like this? I understand the current on the input side/bridge will be higher and the drive will need to be re-rated for this as well as breaker and wiring. I also know that some drives, especially newer ones, monitor phase relationships and would fault in this setup. I am hoping to find 230V input, but 480V is predominant, which means I may end up having to find and incur the cost of a single phase step up transformer. Is this option feasible? Am I really saving anything i.e. power usage, motor lifespan, etc.? I've seen some good deals on Ebay for AB drives. With all that being said, what other ins and outs might I encounter and if anyone is using a setup like this, what drive are you using, etc. I am mainly looking for the soft start capability, but thought a drive would give me more flexibility as I go forward. I would be interested in finding a good soft start for a single phase option too if anyone has an opinion on that. I was looking at a Baldor soft start and thought it was expensive for what it was. I'm just needing some help determining the best long term option. This setup will be for a 5HP Leeson motor @20.8A driving a 15 or 16" impeller (Bill Pentz' design or Clearvue; havn't decided to build or buy yet) Thanks, Bobby

[Mike Cruz]

Robert, sorry, I got a little confused about your post. If you are asking if single phase 220 input to 3 phase output is possible, then the answer is a very simple yes. The TECO FM-50 does this very well and is cost efficient. I have 4 of them in my shop. One on a band saw, one on a sander, and two on two lathes.

I'm fairly certain they have 5 hp versions. Factorymation.com ought to have them.

[Chris Parks]

Nearly all Clearvue cyclones in Australia use a 4KW VFD to drive them. Prior to using an Australian motor we were using the Leeson with this VFD, 230V single phase in, 230V three phase out running current is under ten amps.

[Robert Murphy]

I'll check those out. I was mainly asking about faking a 3 phase input drive out with single phase power. The reason I was leaning in this direction was because I seen some deals on name brand (AB & ABB) drives and despite the fact that these are used, I believe you typically get what you pay for. Maybe TECO or another brand is just as good and I need to not be so close minded. Thanks for the info.

[Carl Beckett]

I have a phase a matic static phase converter. This uses a capacitor bank to start, and then runs the three phase motor off single phase power.

Dont know if this is what you meant by faking it out?

[Robert Murphy]

I wasn't planning on using a phase converter, but I suppose it's an option I should explore. My line of thinking started with soft start, and then shifted to vfd because I figured I could get it done for the same cost or even less with a used product and have more capability. The thread is intended for ideas, information, pros and cons of vfd, so thanks. When I say "faking it out" I mean hooking 220V single phase to L1 & L3 on the input side of a 3 phase drive.

[eugene thomas]

As fsr as how to wire the vfd , it dependd on the spicitic vfd using

[David Kumm]

Yes, Robert, almost all three phase input vfds allow you to use a single phase 230 input and derate. I generally buy used larger drives and they are all three phase input. Some state it in the manual, some don't but if you call the tech line you will find out. My Hitachi J300 require two of the input terminals be jumped so in effect power is entering all three terminals but that is the only brand that I have that requires that. Most work off either L1 and L2 or L1 and L3. It is necessary to use single phase input even when you have a converter as the manufactured leg voltage is often too high and will fry the vfd. Dave

[Robert Murphy]

Thanks for the input. I've seen some Hitachi's on Ebay but had not given them much attention.

[Rollie Meyers]

I have a phase a matic static phase converter. This uses a capacitor bank to start, and then runs the three phase motor off single phase power.

Dont know if this is what you meant by faking it out?


Your static converter starts a 3Ø motor then drops out, the 3 phase motor is just single phasing after that.

[Rick Fisher]

The Teco FM-50 is basically a phase converter .. They give you single phase specs.. It will run most 3 phase x 3hp motors .. costs about $200.00

When I say its basically a phase converter, its a drive and offers the features of a drive, but mostly it gets used to run 3 phase machines in home shops .. ( at least by this crew :) )

[Alan Schaffter]

All that being said- some heads up-

Once you get above 3 hp, VFD's start to become really pricey- pushing $1000. Running a 3 ph DC motor on single phase is one thing, but it is pretty expensive just to do it for soft start which I see absolutely no need for with a Dust collector motor.

Before you buy a used VFD from Ebay, etc. make sure it comes with a manual or you can get a manual online or from the manufacturer. Many low hp and most, if not all, higher hp VFDs have a many, many programmable functions. While you can probably operate the VFD once it is restored to factory defaults, you will want to set others- like soft start ramp time, constant torque, braking, etc., etc. You'll need to know how to do it.

VFD manufacturers and manuals are often not clear about the KW (hp) rating and the need to derate. Some will be clear that when the VFD is powered by single phase you must derate the KW capacity. Others are designed so this isn't necessary.

Almost all VFDs require a minimum of 230V input, some 480V, some are dual voltage. 120V units may exist, but I have never seen nor heard of one.

[David Kumm]

Sounds like you are leaving the single phase motor and only wanting a vfd for soft start and thinking you can wire the single phase motor to two output terminals? Sounds like a bad idea or at least an expensive option for little gain. I do disagree with Alan though as I believe a dust collector is a perfect choice for a three phase motor run with a vfd. Three phase motors are more efficient and the soft start and three phase allow for multiple starts and stops without the problems encountered using single phase motors and starting them under load. Very few can engineer a system to perfectly utilize the maximum capability of the motor and impeller. Depending on the rpm limits of the impeller, a VFD gives you the ability to adjust the speed to maximize cfm at all gates, near and far, large and small. I generally run my 7.5 hp DC at 55-65 hz depending on application and need. In addition you can program the VFD to display amp draw continuously. Once you know the amp draw with a certain gate open and the filters clean you can tell when the filters are filling up by the reduction in amp draw. When my amps drop approx 1/2 amp I know it's time to blow out the filters- or increase the speed if I'm lazy. A 30 amp input VFD three phase costs 350-500 used and 700-900 new although I've bought many used and no new. Given that prices for new are dropping and the cost of used larger units are increasing, new looks better than it did a few years ago. Dave

[Alan Schaffter]

Let me clarify- for the cost, I see no reason for a VFD to provide soft start for a DC. Unless you jump from machine to machine faster than a speeding bullet and turn the DC off each time, the typically recommended max of 6 starts per hour is easy to avoid. It is really easy if you just leave the blower running with gates closed. That is easier on the motor than any start or running with a gate (or more) open. If the noise bothers you, put the DC in a sound cabinet or in a shed outside. I have a very old 20 years(?) Chiwanese Grizzly DC motor that I bought from a lumber yard that went under. They used and abused it as evidenced by the condition of the DC. I have used it for the last ten years and never gave much thought to over-cycling. Other than polishing the start switch contacts once in ten years and replacing the start capacitor last year, I have never had a problem with this motor.

As far as using amp draw as an indicator of clogged filters, first I don't recommend filters at all, and second, if you do have a filter, you can do the same thing for just a few cents by making a slack tube manometer.

As to adjusting the RPM to adjust the CFM- I would hope the impeller is designed for the load RPM of the motor so that over-speeding may not improve CFM. I'm not up on my fluid dynamics but over-speeding could actually result in a decrease in CFM as excessive impeller tip speed results in either stalling (like compressor stall in a jet engine- been there, done that) or excessive turbulence, akin to cavitation.

Also, I see no reason to decrease the RPM of a blower, EVER! It will obviously decrease CFM and Static Pressure! More CFM and SP are always better.

[Chris Parks]

All that being said- some heads up-

Once you get above 3 hp, VFD's start to become really pricey- pushing $1000.

Alan, that is not our experience. We are running 5hp Leeson motors on Asian sourced VFD's for under $400 a unit. The first installations are getting on for over two years old now with not one single problem reported. This was forced on us by the difference in power supplies between Australia and the US and the need to utilise the VFD to raise the speed back to 3450 rpm and also needing to run the leeson from a 220V single phase power source.

[Alan Schaffter]

Alan, that is not our experience. We are running 5hp Leeson motors on Asian sourced VFD's for under $400 a unit. The first installations are getting on for over two years old now with not one single problem reported. This was forced on us by the difference in power supplies between Australia and the US and the need to utilize the VFD to raise the speed back to 3450 rpm and also needing to run the leeson from a 220V single phase power source.

You have a different situation that might justify a VFD, but I suspect it is still more than the price of good used motor as long as your impeller matches. Regardless of the price, still a lot of money for soft start. Two solutions mentioned on the ClearVue website are- mechanical (pulley and v-belt) which would be cheaper, or going with a larger impeller.

[David Kumm]

Alan, your points are valid. Like anything else it depends on the circumstance. I'm running about 2000 cfm over long runs and there is no way to avoid filters. That's a lot of air to send out in the winter or even when humid. You are absolutely correct that the impeller not only needs to be designed to handle higher rpm but also must move more air at higher speed. Most hobby systems run backward inclined or curved blades that operate within a narrow rpm and amp range to avoid burning out motors. They also don't handle high pressure very well so you can't pull lots of air through undersized pipe. I run a straight radial which solves the pressure problems caused by 60' runs but can easily overamp a motor. They need to be monitored but the benefit is more air-7000-9000 fpm through any pipe from 8' to 4". They tend to be loud so I slow it down when just using it to clean the air in the shop. The DC filters are better than the ambient and faster so it serves double duty although not necessarily energy efficient. The impeller itself is a material handling type so it was engineered for a push through system and weighs about 30 lbs. Needless to say the motor shaft and bearings need to handle the speed and weight as well. There are a bunch of things to be careful of- like everything else- but it's worth it to me. And three phase motors are cheap enough used that you can afford the vfd or the RPC and then you have an excuse for old industrial stuff. Dave

[Chris Parks]

You have a different situation that might justify a VFD, but I suspect it is still more than the price of good used motor as long as your impeller matches. Regardless of the price, still a lot of money for soft start. Two solutions mentioned on the ClearVue website are- mechanical (pulley and v-belt) which would be cheaper, or going with a larger impeller.

This may be out of context as I am not sure how to read the above. In our case a change of motor will do nothing in restoring the lost motor speed we experience.

I was originally addressing the cost of a VFD being a thousand dollars where we have found that an adequate solution can be had for way less. I can supply contact details if anyone wants them BTW for direct supply from the Chinese manufacturer. Dealing with these people has been the easiest experience I have had for a long time and no one should feel intimidated by any language difficulty as there are none. They speak and write near perfect English but it is a pity their operating manuals are not written as well. The units we use allow two keyboards to control a single VFD and these can be remotely mounted at the machine(s) using ethernet cables and a splitter. Another advantage of the one we use is profiles can be written to enable different operating situations to be allowed for.

[Alan Schaffter]

Chris, I understand. I took a chance once and ordered a device directly from a PRC company. Item cost and shipping weren't bad- these guys really want to sell their products to the rest of the world. The only thing I would be concerned about is the manual and after sales support.

[Chris Parks]

After sales support from the company I deal with is awesome in capitals. I had some questions so I emailed to them and within five minutes they were on the phone to explain to me what I needed to know. I most probably buy thirty units a year and they treat me like I am their best customer! The manual is definitely a let down as translating technical stuff is always difficult but we get by.

[Stephen Cherry]

http://www.driveswarehouse.com/p-2134-x200-075lfu.aspx

To me, this looks like a well documented, industrial quality drive. They even publish specs on how to run single phase, or with external rectification. Not cheap, but it is an alternative to the non-documented drives (which can be OK also).

[Alan Schaffter]

http://www.driveswarehouse.com/p-2134-x200-075lfu.aspx

To me, this looks like a well documented, industrial quality drive. They even publish specs on how to run single phase, or with external rectification. Not cheap, but it is an alternative to the non-documented drives (which can be OK also).

Unfortunately, according to the manual, the specific model number at the link has an LFU suffix so will only accept three phase input. He would need one with a model number having an NFE (single phase input) or NFU (single or three phase input) suffix.

The number of Instruction Manual pages of !WARNINGs! really cracks me up. I got bored and stopped counting after 8!!!

[Stephen Cherry]

Unfortunately, according to the manual, the specific model number at the link has an LFU suffix so will only accept three phase input. He would need one with a model number having an NFE (single phase input) or NFU (single or three phase input) suffix.

The number of Instruction Manual pages of !WARNINGs! really cracks me up. I got bored and stopped counting after 8!!!

Alan- as for all well documented products, there are plenty of documents:

http://www.hitachi-america.us/supportingdocs/forbus/inverters/Support/AN032404-1_Rev_A_Sizing_for_Single-Phase.pdf

There are others that tell how to use external rectification, etc. This would get rid of the need for uprating to a 10 hp drive for a 5 hp motor.

[David Kumm]

I've been using the Hitachi LFU series for years with single phase input so it does work. Dave

[Alan Schaffter]

I've been using the Hitachi LFU series for years with single phase input so it does work. Dave

They make mention of that in the manual, but say to call tech support. Since the input is rectified to DC anyway before it is converted to 3 phase, I think many, if not most three phase VFD's can probably run on single phase if the input circuits have the require capacity. It is probably rarely discussed in the high horsepower VFD manuals, because most end users of bigger machinery have three phase available/already running the machinery on 3 phase.