You are not registered yet. Please click here to register!


 
 
plc storereviewsdownloads
This board is for PLC Related Q&A ONLY. Please DON'T use it for advertising, etc.
 
Try our online PLC Simulator- FREE.  Click here now to try it.

---------->>>>>Get FREE PLC Programming Tips

New Here? Please read this important info!!!


Go Back   PLCS.net - Interactive Q & A > PLCS.net - Interactive Q & A > LIVE PLC Questions And Answers

PLC training tools sale

Reply
 
Thread Tools Display Modes
Old May 24th, 2004, 11:43 AM   #1
firebrd10
Member
United States

firebrd10 is offline
 
Join Date: Sep 2003
Location: Kentucky
Posts: 61
VFD Question (Home Project)

OK Guys!

A friend of mine just bought a piece of equipment that requires 3 phase power to run.
He wants to run it in his garage were there is only single phase.
He heard you could hook up a VFD and make it work.
I have never heard or do I believe that this is possible but I am willing for someone to prove me wrong.

Specs.
15HP
208 3PH
Trying to make run with 110/220 1PH.

Any Ideas are appreciated.

Tim
  Reply With Quote
Old May 24th, 2004, 12:01 PM   #2
LJBMatt
Member
United States

LJBMatt is offline
 
Join Date: Apr 2004
Location: Dayton, OH
Posts: 430
I've done projects where there was only 230 single phase available but needed 230 3-phase to operate pumps. It can be done but with a few caveats. The VFD must be sized (approx. do your own current calculations) 4 times higher than necessary to handle the power requirements of changing single phase to 3 phase (SCR size). The drive must also be disabled for phase imbalance. If your motor is 15HP 230 3-phase then you will need approximately a 75 HP VFD to give you the output power necessary to run at full load. It can be done but do the calculations to determine your input and output loads. For that size of VFD you'll probably be better off getting a transformer.
__________________
Matt Stefanski

Go Dayton Flyers!
  Reply With Quote
Old May 24th, 2004, 12:06 PM   #3
Jiri Toman
Member
United States

Jiri Toman is offline
 
Jiri Toman's Avatar
 
Join Date: Jun 2002
Posts: 498
yes you can

There are all kinds of Drive makers out there that produce
a single phase in, 3 phase out AC drive. Check out Reliance, part of
Rockwell now. I have used their single phase in, three phase out drives on few projects and they work great.
You should also make sure that you have enough power in your garage
to run 15 HP motor.
  Reply With Quote
Old May 24th, 2004, 03:04 PM   #4
icky812
Lifetime Supporting Member
United States

icky812 is offline
 
icky812's Avatar
 
Join Date: May 2002
Location: Cumming, GA
Posts: 691
It can be done, but you had best expect to pay several thousand dollars for the drive. Perhaps you might fine a used one, but it will still be some fairly large bucks.

LJBMatt is right, depending on the manufacturer of the drive it will need to be oversized from 2x to 4x to get it to work properly. Plus your garage and wiring will need to be able to carry the loading. If you were running three phase the motor would be carrying 42 amps. On single phase it will be much more than that, so wiring to the VFD will have to be capable of carrying the excess current.

$$$$

Last edited by icky812; May 24th, 2004 at 03:06 PM.
  Reply With Quote
Old May 24th, 2004, 03:49 PM   #5
Guess
Guest
 
Posts: n/a
If you take a good look at the spec sheets from ANY brand you will find that if they can be connected to a single phase (and most of them can) you need to versize the drive by xxx. Usually only one size up.

So for a 2HP motor, if the size would be a 3 HP drive, hen you select a 5 HP drive and it works pretty good.

The problem is never the output of the inverter but the input size. To charge them capacitor you need to pass as much current into one phase as you would in three, so the need for a bigger inverter, for the INPUT side of things.
  Reply With Quote
Old May 24th, 2004, 05:42 PM   #6
Thomas Sullens
Member
United States

Thomas Sullens is offline
 
Join Date: Feb 2004
Location: Idabel, Ok
Posts: 390
Hi firebrd10

Why don`t you build him a phase converter they are simple and work good. Go to google and type in phase converter and you`ll get more info than you can say grace over.

Tom
  Reply With Quote
Old May 24th, 2004, 10:06 PM   #7
Shawn Cassidy
Member
Canada

Shawn Cassidy is offline
 
Shawn Cassidy's Avatar
 
Join Date: Mar 2004
Location: Montreal
Posts: 98
I've worked on something called a Rotophase before. They're common in lathe and milling machine applications where 3 phase power is not available. This converter connects to 240 volt single phase (house voltage) and outputs 600 volt 3 phase. It consists of a step-up transformer (240v to 600v single phase) a bank of capacitors and a motor used as a generator... I believe. You can select different models to suite your specific application. You select according to the HP of your motor. I don't know if this product is still on the market? I think the company was based in Toronto, Canada. The model I worked on was a 10HP, 600 volt. /www.3phasepower.com is a site that offers something similiar to a Rotophase.

Last edited by Shawn Cassidy; May 24th, 2004 at 10:16 PM.
  Reply With Quote
Old May 25th, 2004, 06:59 AM   #8
DickDV
Member
United States

DickDV is offline
 
Join Date: May 2002
Location: Kalamazoo MI
Posts: 2,313
A couple of things on this subject need to be clarified. First, the normal derate for VFD output current when single-phasing the input is 50%, not 4/1 or 6/1. Second, a VFD is a poor choice for a phase converter if the motor or motors are to be start/stopped independently of the inverter. Throwing a stationary motor across the output of an inverter that is "up to speed" will almost surely result in an inverter fault. Acceptable operation is only possible by starting and stopping the motor and inverter as an operationally- matched pair.

In my view, the old rotary converters, while inefficient, are still the best choice when you are dealing with multiple motors and random start/stops.

And, yes, the size of the single phase service gets pretty hefty at 15hp. Let's see here, 15hp is 11.2kw so the single-phase service will have to supply that plus a little for inefficiencies. At 220VAC single-phase, that would work out to 51amps plus whatever the losses and inrushes are. A 100amp service wouldn't be too large, would it?
  Reply With Quote
Old May 25th, 2004, 08:01 AM   #9
glenncovington
Lifetime Supporting Member
United States

glenncovington is offline
 
glenncovington's Avatar
 
Join Date: Apr 2002
Location: Gloucester, VA
Posts: 268
You may want to check out these rotary converters.

http://www.gentecphaseconverters.com/
  Reply With Quote
Old May 25th, 2004, 04:40 PM   #10
paradym
Member
United States

paradym is offline
 
paradym's Avatar
 
Join Date: Mar 2003
Location: Los Angeles
Posts: 86
Another option are Static Converters, which are basic cap banks that fake out the phases, not as efficent as rotarys.

Here's a site for them -

http://www.phaseconverter.com/what-is-static.html

Quote from site -

"The static phase converter does not actually generate 3-phase power continuously as a rotary phase converter does, but only long enough for it to start up. Once the motor has started the static phase converter circuitry disconnects itself and the motor continues to run on single-phase power; because only two of three windings receive power during running, power output is reduced to 1/2 to 2/3. A 15 HP motor will start with the power of a 15 but run as a 7.5 for example."
__________________
RHODE'S COROLLARY TO HOARE'S LAW
Inside every complex and unworkable program is a useful routine struggling to be free.

ROBERT E. LEE'S TRUCE
Judgment comes from experience; experience comes from poor judgment.
  Reply With Quote
Old May 25th, 2004, 06:18 PM   #11
Doug_Adam
Member
Australia

Doug_Adam is offline
 
Doug_Adam's Avatar
 
Join Date: Sep 2002
Location: Perth
Posts: 949
What about a 3 phase diesel (or petrol/gasoline) electric generator?
This will give heaps of power, and I think they are not too expensive.
Just have to be run outside, and watch for fumes.

Doug
  Reply With Quote
Old May 25th, 2004, 10:05 PM   #12
Eric Nelson
Lifetime Supporting Member + Moderator
United States

Eric Nelson is offline
 
Eric Nelson's Avatar
 
Join Date: Apr 2002
Location: Randolph, NJ
Posts: 4,346
While searching for something completely different, I stumbled across THIS old thread which may be helpful to Tim.

Maybe Pierre can give us an update on what he wound up doing?...

beerchug

-Eric
  Reply With Quote
Old May 25th, 2004, 10:59 PM   #13
CaseyK
Member
United States

CaseyK is offline
 
CaseyK's Avatar
 
Join Date: Feb 2004
Location: In the cornfields, on the prarie, outside Chi-Town, a few miles beyond the boondocks.
Posts: 1,731
Lightbulb

I recommend rotoary phase converters over static converters. Static converters sometimes (not always) generate emf / rf interference.

I belive that rotary units are less expensive.

Trying to figure out a rotary unit one time, my best guess is as follows:

A motor, possibly with a permanent magnet armature, is configured for 3 phase open delta (two windings). Single phase input hooked up to motor windings A and B, 3 phase output to A and B and C. Armature turning induces current (magically?) from first winding to second winding. Due to design, it automatically phase shifted. It all makes perfect sense when seeing how electric utilities get by with suplying open delta 240 to older factories and the majority of farms around the country. Normal winding is center tapped for 120/240 normal house wiring and the wild leg on the open winding floats voltage wise with load. Wild leg is typically 208 volts to ground and should only be used for third phase. They are typically 1.5-2 times the size of the motor that you want to use.

Hopefully, this makes sense, it is perfectly clear in my mind.

Anyway, I figured it out from literature for this link....

http://www.ronkelectrical.com/pages/home.html

regards.....casey
  Reply With Quote
Old May 26th, 2004, 12:29 AM   #14
CaseyK
Member
United States

CaseyK is offline
 
CaseyK's Avatar
 
Join Date: Feb 2004
Location: In the cornfields, on the prarie, outside Chi-Town, a few miles beyond the boondocks.
Posts: 1,731
15 hp is kinda large, and the price of a converter will be also. A new 25hp 240 listed on eBay was $1295, and 15hp ranged from $875-$1995.

As an electrical contractor, I've received a lot of calls from people who bought 3-phase equipment because it was a bargain. New electric service is 2-3 times more expensive, and locally, all utilities charge extra for 3-phase service, whether you are using it or single phase loads. Usually the calls are from restaurants or smalll tavers that found a great deal on a cooler. Generally, the wing up with a new single phase motor by the time they are done comparing all the costs.

regards...casey
  Reply With Quote
Old May 26th, 2004, 08:25 PM   #15
stvsas
Member
United States

stvsas is offline
 
stvsas's Avatar
 
Join Date: Feb 2004
Location: leominster, Ma
Posts: 75
VFD Question

I saw this done once in NC. This fellow had a milling machine in his garage. It had a 5 hp 3 phase motor on it. To generate the 3 phase for it, he had another 3 phase motor acting as a generator in this manner. The single phase 240 was wired to 2 of the 3 phase motor leads. The 3 leads from the milling machine were wired to the 3 leads on the other 3 phase motor. He had another motor yet (single phase) turning the 3 phase motor with a belt and pulleys. By having the motors spinning. the 3 phase was induced in the generator motor and sent to the milling machine. If I had not seen it, I would not believe it. Hope this helps.
  Reply With Quote
Reply
Jump to Live PLC Question and Answer Forum

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Topics
Thread Thread Starter Forum Replies Last Post
home project guest LIVE PLC Questions And Answers 26 February 23rd, 2005 11:01 AM
VFD training class was awesome! Question about Carrier Frequency... Russ LIVE PLC Questions And Answers 2 September 17th, 2004 07:28 AM
HMI for home project andydaoust LIVE PLC Questions And Answers 8 February 5th, 2004 01:22 PM
Home Project Time Bob O LIVE PLC Questions And Answers 6 September 25th, 2003 04:29 PM
VFD Question harryg LIVE PLC Questions And Answers 28 January 23rd, 2003 06:24 PM


All times are GMT -5. The time now is 02:31 PM.


.