×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Single Phase source Three phase Out Drive

Single Phase source Three phase Out Drive

Single Phase source Three phase Out Drive

(OP)
I have single 120/240V 400A service.  

What is the largest three phase motor that drive equipment can power?

RE: Single Phase source Three phase Out Drive

0 hp.  You at least need a three phase service or some sort of phase conversion equipment to get to 3 phase.

RE: Single Phase source Three phase Out Drive

Depends on if you are looking at a mechinical or electronic converter, or there maybe a hybred type out there.

Why don't you Google it and let us know.

RE: Single Phase source Three phase Out Drive

Assuming you do intend to use a converter of some kind, inverter-type VFDs designed for the purpose tend to be available up to no more than about 4kW. After that you can usually push a three-phase input drive into service with a bit of effort (add DC bus capacitance) and de-rating (halve it). That gets kinda expensive quite quickly.

Motor-generator sets are available in enormous ratings, but I think you'll struggle to find a really large single phase motor to drive one: about 25HP is the highest I've seen, and that was a real old one from some piece of farm machinery.

Phase converters are available up to reasonably large ratings but the third phase they produce is not very good - weak and it doesn't have a true 120° phase displacement - plus they normally need to be tuned to the load they serve.

Have you asked the utility to cost installing a 3-phase supply?
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Single Phase source Three phase Out Drive

Look at VFD.  Single phase in and 3 phase out are common.  I don't know how big they come but they work fine on gate operators where there is just a single phase line running by. You can probably save the cost of the drive on the motor.  Single phase motors in 4 or 5 HP are not cheap and they are hard to find.  

RE: Single Phase source Three phase Out Drive

Any 3 phase VFD is theoretically capable of acting as a "phase converter", but not all will do it because some have phase loss protection on the front-end that cannot be defeated. So assuming you get around that issue, the maximum size is at that point only limited by your supply capacity. You say you have a 400A service, but how much is already running on it?

BTW are you the same Bill I already answered this question for in another forum, but where you had a 200A service? If not, read this.
http://forums.mikeholt.com/showthread.php?t=123505
If so, your 400A service obviously increases the limit. But as I said in that other thread, there are other issues at hand.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln  
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies  

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources