1ph or 3ph

[arnettda]

I am looking at installing a irigation pump. Well driller wants to put in three phase pump. I only have single phase at building. 3ph is 450 feet away. Would it be worth putting in 3ph to use a 3ph pump or just stay single phase.
I have post in NEC about yakawa drive which they say if you put 1ph in you get 3ph out. It is a 10hp pump. Thanks

 

[JacksonburgFarmer]

On alot of the hog barns we do, they usually have two pumps, and have "controllers" that are basically Frequency drives that have single phase input with three phase output. works pretty well. (I know that my hog barns having two well pumps has nothing to do with your project) Those always worked pretty "well".

 

[JacksonburgFarmer]

Well....I just re read your post....and I am very tired....lets try this again..
How far is the distance for single phase source???
What is the difference in distance from single phase to three phase?
Add up your cost differences, and energy savings, and remember that in future, three phase motor is cheaper to replace than single phase....but may have to be replaced more often...

 

[charlietuna]

I would go to an oversized three phase feeder rather than using a drive to create the three phase. More dependable and more efficient.

 

[iMuse97]

There are couple I considered having been involved a very similar situation on a farm:

1. is the 3P medium voltage at 450' away?

If so, will the POCO install poles and Trannies for you at a reasonable fee? In the case I'm thinking of, they said it would cost $4000.+ but only charged $1500. saying they could make it up on the monthly billing. This 15HP motor is used 5-6 mos. of the year averaging 30-50 hrs per week.

2. If it is 3P 480 then I'd go with Tuna's idea.

 

[arnettda]

Thanks for the replys. The building has 1ph power which is 450ft away from the three phase source. The controller will go within 10ft of the single phase panel. I will give POCO a call and see what they will charge for a new service. I would have to abandon the single phase panel in there now if I get a new service installed?

 

[Rick Christopherson]

I would be more inclined to run the 3-phase line. I don't know why that would force you to abandon the single phase panel, but I am not an expert in that area.

If you go with a VFD, you will need to derate the VFD by sqrt-3 in order to connect it to 1-phase input. That means you need a VFD about 17 hp (confirm this with manufacturer), and that is going to be pretty costly too. This derating is because the VFD rectifies the incoming AC signal, which is why you can run one from 1-phase power, but the rectifiers are limited by amperage, and 3-phase rectification is more efficient than from single-phase.

A 10 hp single-phase motor is going to be much more expensive, plus will require larger conductor sizing. If the pump is starting under load, it will be more prone to failure.

 

[Smart $]

... I would have to abandon the single phase panel in there now if I get a new service installed?

No. Two services of differing volatge and/or phase characteristics are permitted [230.2(D)]

 

[ptonsparky]

A seasonal load like irrigation would require a minimum billing from POCOs in this area. They may not be willing to extend primary just for 10HP but 450' is not that great of a distance for 480. Do you own the ground between building & 3ph? If so, bury your own underground. As stated above, you will have to do the math.