Three Phase From Single Phase

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jtester

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Las Cruces N.M.
I have a client who wants a deep well pump, +/-100hp, but only has single phase power available. What is the largest realistic motor hp when you use a VFD with a single phase input and a 3 phase output.

Thanks in advance

Jim T
 
barbeer said:
http://www.phase-a-matic.com/?gclid=CMHT6-CF1IkCFRoqSgodIRqszA

Google is cool! The brochures say possible of 3x the output to input (or something like that)
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Google is cool but Phase-A-Matic is not magic.

One thing is certain; the power output will be less than the power input.

How much single phase power is available? You would probably need on the order of 200 kW to start a 100 HP motor. Phase-A-Matic recommends that the converter be sized to at least 50% larger than the largest motor. Therefore, for a 100 HP pump, you need a 150 HP or larger rotary converter. That is a "consult factory" size.

The big issue is, how much single phase power will the power company deliver to a site?
 
I can not speak for your area, of course, but I beleive the POCO in this area require you to consult them on any motor installation over a certain HP (25? Can't remember off the top of my head). I think you should check with their requirements
 
John,

Boater Bill seems to be on the inside track on VFD's here in the forum.
 
Thanks for the fast replies. I am talking with the POCO, a local co-operative who doesn't have an engineer in the office. This well is in the middle of nowhere and I believe that the POCO will have trouble with any significant load. I am trying influence the civil engineers thoughts on the motor size and when he gets it as small as is practical, we'll let the Co-op consultant do the system calculations.

I am wondering, from your experience, how big a motor have you done with the static type converters. The Phase-O-Matic lists models up to 50 hp. Theory would let you go larger. The engineer wants 100 hp, and I'm telling him he can't have it.

Thanks again

Jim T
 
We were called to a job to check a motor generator issue, the motor generator was off line and the customer?s art ($21, 000, 00.00 worth) was getting warm, and humidity was exceeding determined levels.

What we found was the following. The contractor had installed the specified 3 phase chiller, and the utility was going to install 3 phase service, but coordination was off. The utility originally quoted about 1, 000,000.00 for 3 phase service, after review the revised cost was a bit over $5,000,000.00. So a second option was proposed, install 3 parallel 3 phase rotary converters. But it seems the chiller phase monitor would not operate with the 3 phase voltage A-B 208, B-C 208, C-A 240. The chiller manufactured said this would void the warranty. So the contractor installed a 100 HP motor generator (motor generator manufacture modified the MG operational controls to permit input voltages at this level) fed from the phase converters that then fed the chiller.

Final outcome the system cost a lot to install and is about 36% efficient at full load. And lastly the Diesel generator (not the motor generator) that was installed to back all this up blew up 3 days after warranty expired.
 
Keep in mind that, even with 100% efficiency, any converter, rotary or otherwise, cannot deliver more power (watts, Kva, HP, etc.) than you supply to it.
 
I would check with the POCO if they won't supply the three-phase, maybe they would...biting my tongue here... go open delta.
Ugh I said it. (Anyone have a Certs?):grin:

The 100 HP pump would require a 200-225 HP VFD. $$$$$$$$$$ There wouldn't be a large inrush current for the motor if it's on a VFD so the POCO won't calculate their feeders as a motor load.

Can the civil guy possibly specify 2-50HP pumps or 3-40 HP pumps? Then the VFD costs would go down and there would be redundancy in the system if one pump needs maintenence or has a failure.

BTW, thanks for the vote of confidence Rocky. I 'm just trying to help just like everyone else here.
 
While technically a 200HP 230V VFD would work (assuming you can find one), the single phase input current for that motor is going to be around 430A! You had better make sure that when the utility says they will only deliver 1 phase power to you, they understand how MUCH power you need.

In some rural areas why will drop 480V 1 phase power, in which case you will only need 215A, but then you may have a bit of trouble finding a 480V VFD that size which does not have Phase Loss protection. Many larger VFDs now have SCR front-ends instead of just diodes (to avoid charging inrush) and the SCR firing circuits will not work on 1 phase input.

As another option, there is a company called Precise Power http://www.precisepwr.com/single_phase_motors.asp?bhcp=1 who makes a ;written pole" 1 phase motor. Their website says up to 75HP, but they have a Canadian partner who has done a 100HP version I have heard. Might be worth talking to them. These are not conventional motors so service and repairs may be an issue, but then again you don't have a conventional application.

Good luck.
 
Just to provide closure. I talked to the Co-op engineer, and he says it is +/- 100 miles to the substation from the well site. The line is 14.4kv single phase for the last 10 miles and then 3 phase from there. The majority of the line is #4ACSR.

The long and the short is that I doubt we can start much beyond 10 hp or so. I'll let the civil engineer decide, and call the Co-op back.

Thanks for all your help.

Jim T
 
Generator to get the puppy on line then close tranistion ATS to supply power from the utility, of course it would have to run pretty much full time.

And Larry are next your going to tell me there are no free lunches?
 
Someone needs to be doing some serious "system design" and engineering to figure out the means and the economics of doing the job, and even to figure out what job needs to be done. There is more to it than figuring out what size pump you can start at the end of a 10-mile 14.4 kV single phase line.

You can buy large "base load" engine generators that operate on diesel fuel or natural gas that will make enough electricity to start and run any pump you want. The diesels operate at about 40% efficiency of conversion from fuel to electricity; about 220 grams of fuel per kWHr. http://www.perkins.com/cda/layout?m=97355&x=7
 
brian john said:
And Larry are next your going to tell me there are no free lunches?
Click to expand...
Hey, I'm sorry for stating the obvious, but the first couple of posts hinted at not understanding that, and it's far from the first time it's happened, at least with me.

You've never experienced someone wondering why there can be such a differnce in conductor size between tansformer primary and secondary conductors?
 
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