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04-14-2008, 11:50 PM #1
220 V 1 ph input to 440 3ph out VFD?
I'm looking to power a 1.5 hp 3 ph 440 motor (lathe) from my 220v single shop with hand knob speed control. What VFD make/model and price do you recommend.
04-15-2008, 12:03 AM #2
I found some voltage doublers that take 110/120 in and put out 220/240, but none that double from 220 to 440. They may exist, but there are none listed in the limited manufacturer literature in my reference folder.
The options at driveswarehouse.com do not even include output voltage as a parameter distinct from input voltage.
Some three-phase motors can be configured for either 220 or 440 by changing the connections. Have you checked the label inside the connection box on the motor?
04-15-2008, 10:58 AM #3
You need a 480 / 240 volt transformer to step up the 240 volt to 480 then feed this to a 3 phase input / 3 phase output VFD (VFD must be one that will run on single phase in although it is a three phase model--many will work this way).
I have two machines running this way and here is my setup:
30 amp single phase disconnect switch w/ 20 amp fuses
3 kva 480 / 240 transformer connected with the 240 side to the disconnect and the 480 side to the VFD
3 pole fuse holder with 10 amp fuses just after the transformer and before the VFD
3 horsepower rated VFD, 460 volts input / 230 volts output, 3 phase in and out.
When you run a three phase VFD on single phase you must derate the VFD horsepower rating to 50% of the nameplate. This is why you need the 3 hp, or larger, VFD.
This is a lot of rigging but it does make a very nice drive. I have this setup on a 1.5 hp geared head drill press and I have another on a 2 hp patternmakers lathe.
Contact me my private message if you need more info. I will send a phone number as I have little computer time available.
04-15-2008, 01:43 PM #4
I'm pretty sure my Hitachi SJ VFD drives do not require derating when used as single phase input. Maybe it's because they are designed for either single or 3 phase input?
If you use a larger VFD than the motor name plates, program the output current registers to that of the motor (within reason..) for overload protection.
04-15-2008, 01:50 PM #5
There are no single phase 460 volt VFDs so everything he can use will require derating.
single phase input VFDs are available in 230 volt models and some are dual rated but not so in the 460 volt VFDs
04-15-2008, 09:59 PM #6
04-15-2008, 10:23 PM #7
I'm running a 5 HP 3-phase 220 motor from single-phase 220 with an AC Tech SCF-series drive (SF250Y). The drive is designed for this use, and rated for a 5 HP motor load.
Model SF230Y is the 3 HP version of this drive.
The Y suffix on the model number is important, as it identifies drives which can work with single-phase input power.
Datasheet and operator manual can be downloaded from the AC Tech website www.actech.com
They also have a 3 HP 220 volt single-phase input SMV drive, model number ESV222NO2YXB.
I'm sure other manufacturers have comparable products.
04-16-2008, 12:44 AM #8
04-16-2008, 01:09 AM #9
04-16-2008, 01:50 AM #10
I doesn't solve any problem stated here but those interested in stepping up 230 to 460 DC should look at "bridge full wave doublers" on your favorite search engine. Sufficently large bridge rectifiers and coupling capacitors can make 230 volt input doublers to 460+ volts DC at 50 amps if the pocket book will bear it.
Be careful when applying this technology to VFD's. The logic power is sometimes supplied from a tiny transformer which will fry when fed DC. It will have to be located and isolated and fed from a separate AC supply - or removed and a suitable logic DC supply provided.
04-16-2008, 10:06 AM #11
You have a simple problem as compared to one orginally stated. You only need a single phase input (230 volts) to three phase output (230 volts) VFD. Try looking at the Hitachi SJ200 sensorless vector models. They are available in single phase input in sizes up to 3 hp. They also support 3 wire control if you need it. I posted a diagram showing how to control one of these using a drum switch. Just search for "SJ200" and look for posts by "toolnut" for the last month or so. The sensorless vector design gives much better low speed performance than volts / Hz drives. If you never intend to operate the VFD below 30% speed then there is no reason to spend money for the sensorless vector type. The vots / hz will do quite well.
Hitachi drives can be found on www.driveswarehouse.com I have also used Toshiba drives as well as a couple others.
04-16-2008, 10:39 PM #12
04-16-2008, 11:38 PM #13
I did not write the below and do not recall where I copied it from.
All I know is I copied and pasted it into a word document (in 2001) and saved it for future use.
Who ever wrote the reply sounded like they knew what they were talking about...- I wish now I had down who CAP was.
Karl Townsend wrote:
> I bought a 440 three phase air dryer. Didn't know until it got home that it
> doesn't do 220 3 phase.
> What's best system to convert power for this unit?
> I'm asking now because I see a fairly cheap 440 VFD unit on ebay. I'm
> wondering if some kind of step up xformer and VFD is the way to go.
The task can be accomplished by using a 'donor motor' that is normally doing
the job of single to 3 phase conversion. Normally people call it a rotary
phase converter. Obvisally the load needs to be figured, and any heater loads
dropped down to 220/1 if possible. But is you just want to look at the
'package' conversion.. here goes..
Electric motors of the three phase garden variety type are usually 9 lead
star connected 220/ 440 voltage. One of the interesting things about
electric motors are that they are rotating transformers, that also can make
shaft horsepower. So if you properly connect the motor and put 220/3 into it
you can get 440/3 out of it. There is your cheap 220/440 transformer.
But you need 440/3, so now we need to make the electric motor into a rotary
phase converter, and also wire it as a step up transformer.... So we need to
kill two birds with only one stone... not that hard...
First you need to find your load... lets say 3 amps at 440 volt ( you can do
a lot of work with 440/3 ) So the motor that you need to find has to have a 6
amp name plate on 440 volt. ( double the load is going to be seen on one of
the set of coils, so the coil has to be able to handle the load ) The motor
need to be a nine lead motor star connected... If you don't know, check to see
if leads 7-8-9 all have continuity to each other with all other leads removed.
If they do, you have a star motor.
Now we have to make a rotary converter out of the center star of the motor..
using leads 7-8-9 only...
Find the name plate hp of the donor motor ( 1800 rpm is preferred) and get a
motor run cap ( oil filled type ) of 25 mF per hp.. so if I remember my motors
correctly, you would have found a 7.5 hp unit... so that would be a 187.5 mF
cap ( oil filled). This cap needs to be hooked between your 220 volt leg two,
and the new leg three. So leg one hooks to 7, leg two hooks to 8 and the cap
hooks leg two ( 8 ) to 9.
That is a rotary phase converter,slightly changed for our use. The 'donor'
motor will not want to start to turn, but if turned up to speed it will stay
turning. So we need to add a start circuit. The start circuit needs to drop
into the circuit, a Motor Start Cap ( the plastic can type ) of 10 times the
motor run cap.. so that is a 1875 mf cap ( anything close will do ). If you
put a double throw relay with a 220 volt coil on the lead 8-9, you will find
that with the motor running it will have 250 or so volts on it, but when the
motor is trying to start, the voltage will drop to 110 ( half of the line
voltage... draw it out, you'll see why), at this time the N/C contacts of the
relay will be closed... that's when we need the start cap. When the motor gets
up to speed, the voltage will pull in the relay contact, and drop out the
start cap. That is a fully functional rotary phase converter, using only the
center 3 windings of the motor.
Now for the 220 to 440 conversion.
The motor is wired to the normal 440 volt wiring diagram ( line in should be
1-2-3 and 4/7 5/8 6/9 ) We now have stuff on leads 8 and 9 to make the
motor spin, and we are putting out 220 into leads 7-8-9. so our three phase
440 volt is now available at leads 1-2-3.
To adjust the unit for proper operation, add or ( in your case ) remove some
of the run cap mF value to get the three leads out balanced current.. The 25
mF per Hp is used for a starting point, and my guess is that you will be down
around the 15 mF per Hp range....
I did this trick at work when we lost power all day and I needed to unload
some tankers of wine, and all I had was my 12 kw single phase generator, and a
slew if portable three phase pumps.. I used the 7.5 hp pump as a 'donor' motor
to drive the 1.5 hp pump ( I did not have enough electric generator to run the
7.5 motor pumping a load.. so the 7.5 took the 220/1 up to 440/3 for the 1.5
hp pump) We ran for about 5 hours until the power came back on...
Good luck, and remember... Fuses are your friend... Use them!
04-16-2008, 11:42 PM #14
Rotary transformer is an old trick, useful if you have "extra" motors laying around. But motors are usually more expensive than transformers and transformers tend to not move things very well.
04-17-2008, 06:20 PM #15
I've done this...
I did the rotary transformer trick several years ago- I was in a situation where a friend's 460-only machine needed to be tested, so I lifted and reconfigured the leads of my homemade RPC. It worked, but the available output power is only a quarter of what the motor's ratings indicate, since you've lost half your input power, and pulling only half the output. Running my pal's 1.5hp lathe on a 10hp RPC (or half of one) yielded just enough power to RUN the machine (and prove it), but not enough to work it very well.
I've been working on converting my RPC-fed machines to VFDs, and found that the current market for 220v-single suitable VFDs isn't nearly as impressive as looking up 1/2hp-15hp 'B'-class (460-480) three phase input drives. I've set up two Allen-Bradley 1305's (an aa08a and aa12a) on my radial drill and Bridgeport J, with very happy results, at an expense of about $90 per machine. The Monarch 10EE will get a much more svelte drive... will go 7.5hp into backgear, and instead of trying to go 220 and live with the derate, I'll use the 480/240 transformer in step-up configuration, and use a much larger drive... the end cost impact is much LOWER than trying it any other way. I picked up an Allen-Bradley SV-type 1336S NEW IN BOX for $75, and a suitable (10kva) transformer for $85... still way below what I'd get any-other-way.
Since the 10EE is loosing probably 500lbs of M-G system, putting in a 100lb transformer and a lighter 480v-3-phase AC motor will STILL come out equal or better. If it turns out that the derate is unacceptable, I'll rig the transformer with stout bridge, filter caps and soft-start, and feed direct to the 1336s's DC bus terminals.
04-25-2008, 09:38 PM #16
Does something like this do what is wanted ie adds single phase 240/220v input to any 3ph 460/415 output VSD?
Is this a bridge fullwave doubler mentioned earlier in the thread??
04-26-2008, 03:06 AM #17
A voltage doubler could do it.
I forget how this circuit is done exactly, but you could take some heavy duty diodes and some caps with a VERY HIGH voltage rating, and build a voltage doubler. If you rectify and filter 480v, you get 678v peak to peak. I'd go with a MINIMUM 750vdc cap, and diodes rated for 1200v with about double the needed current rating. You MAY be able to use 400VDC caps in series, but when you put caps in series, they are only 1/2 the MFD. Then you wire your home built voltage doubler to the DC bus of the VFD. A LOT of VFDs have access to the DC bus on the outside of the drive, so you don't even need to open them up. I know Hitachi drives run the control circuitry off the DC bus so there's NO NEED to put AC to it. Maybe somebody can post a schematic for a voltage doubler circuit. I could look at a computer powersupply and see how that's wired on the input. They take the 120v AC and put it through a voltage doubler to get the same voltage as if it were running on 220v. The switch on computer supplies just change the wiring of the caps and diodes on the input from a voltage doubler, to a plain rectifier/filter circuit.
The other option is to get a 220 to 440 transformer, and stick some diodes and caps on the output of it. That's more expensive though, but if you can find a 220 to 440 transformer you're set. It can even be an autotransformer.
04-26-2008, 03:14 AM #18
The drive booster DOES WHAT I SAID!
I know those drive boosters WILL NOT WORK with VFDs with control circuitry that doesn't operate off the DC bus. The way you can tell is if the VFD stays on for a few seconds after power is shut off. The 480v versions of the drive should be the same, but you never know, they might use a transformer, and a separate supply for the control circuitry.
Anyways, that drive booster is nothing more than a rectifier/filter circuit to hook to the DC bus. The ones that take in 240, and crank out 480 are voltage doublers. If that thing is cheap enough, it's worth getting. You can probably build them a LOT cheaper though.
04-26-2008, 03:48 AM #19
04-26-2008, 02:41 PM #20
"You MAY be able to use 400VDC caps in series, but when you put caps in series, they are only 1/2 the MFD."
Most 460 VFDs use two caps rated 450 VDC each in series. That combination is rated 900 for a 625 peak bus.
As always, the series capacitor law applies, and while you DO get twice the working voltage, you also get only one-half the capacitance. There is no free lunch.
"I know those drive boosters WILL NOT WORK with VFDs with control circuitry that doesn't operate off the DC bus."
As was clearly stated in the installation document.
"Anyways, that drive booster is nothing more than a rectifier/filter circuit to hook to the DC bus."
It is, more particularly, a complete replacement for the converter section of the VFD, taking in ac and outputting dc at the dc bus voltage which the VFD expects.