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#185298 03/08/09 11:32 PM
Joined: Feb 2008
Posts: 193
S
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A friend is putting in a 3 phase submersible pump. His well is 720ft deep with the pump at about 700 ft. They are concerned about the torque of a large single phase pump twisting the pipe too much. It is only about a 70 foot run to the power source. He only has single phase power, so I assume there is a converter box somewhere. Is it at the well head or at the breaker. He is getting his pump this week so I should know more then, but I am just trying to get ahead and get a little info about previous experience.

Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
Such pumps are usually integral parts of the well casing (pipe). A million mad horses couldn't shake them loose.

Otherwise, get a three-phase pump and feed it through a frequency drive. This will provide a 'soft start' feature.

Joined: Feb 2003
Posts: 939
F
Member
Most well I useally run into most will have a " toqure arrester " and with 3 pump you can invest a soft start or VFD so you can able ramp up without putting in the stress on the pipes.

How big the pump it is ?

Merci,Marc


Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)

Joined: Aug 2007
Posts: 853
L
Member
Originally Posted by frenchelectrican
Most well I useally run into most will have a " toqure arrester " and with 3 pump you can invest a soft start or VFD so you can able ramp up without putting in the stress on the pipes.

How big the pump it is ?

Merci,Marc


I'll 2nd the question. how big a pump? and what is it for?

Joined: Jul 2004
Posts: 101
J
Member
Just to clarify, the starting torque of an AC motor is generally the same regardless of being 3 phase or single phase. The only thing that would make a difference in using 3 phase is if you use a VFD as a phase converter. But 700 feet is a long distance for a VFD run, so make sure your motor and VFD will not have issues with that. You may need what is called a Long Line Filter or at the very least, a reactor on the output.


JRaef
jraef #185306 03/09/09 08:27 AM
Joined: Feb 2008
Posts: 193
S
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It's going to be a 3hp pump. It will be his primary water supply for his house and his livestock. The county is actually helping with the cost so that he can get his animals out of and fence off the creek.

Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
If it's a three phase pump with a single phase supply, you're pretty much required to use a VFD ... problem solved.

Joined: Jul 2004
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G
Member
Why is he using a 3p pump? How much water can a cow drink?


Greg Fretwell
Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
Greg, 700 ft. is a pretty good amount of head. I suspect a single phase motor is both a lot more expensive, as well as considerably larger in size.

Incidentally ... wells are the one place I find the corner-grounded delta service.

Joined: Jul 2004
Posts: 783
L
Member
How do you deal with the excellent ground rod you just installed, with respect to lightning strikes? When you bond the power system to the well casing, you just made the rest of your electrical system very attractive to lightning.

Larry C

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