3 phase vs 1 phase pump?Both are 2 HP capacity.?

Question

Does 3 phase pump draw less current and save electric bill,if p=i^2×r?

Answer 1

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If you put an ammeter on a typical 1/2 hp single phase motor and on a similar-sized 3 phase one, you will usually find a much greater difference between the idle and full load current on the 3 ph. The full-load efficiency is only one criterion.

In an application where the motor is run continuously at full load, there is a fairly small difference favoring the 3 ph one.

In an intermittent service, like a table saw, the 3 ph will use a lot less electricity and run cooler.

Single-phase motors are mostly pseudo multiphase ones ( at least in startup ) and none of them work really well. There is a reason that there are few single-phase motors larger than 5 hp. Having suffered with single-phase and a couple of different converters, imo, nothing works like a real 3 ph line.

However, most US homes only have 120/240 single phase available.

Answer 2

In theory, yes.

But, the initial extra cost of the 3 phase motor  and necessary 3 phase service, transformers, might take a Long Time to amortize.

I took a wagon  ride at a Maran Pumpkin Patch. We went thru  the cotton fields;  I noted all the well pumps were 3 phase; all had 3 big transformers, too. It was efficient for them, with wire drops of a mile or so between them and TEP. The wells were over 800' deep, too. 

Answer 3

In USA, 3-phase electricity is generally only available at commercial and industrial locations, not at domestic locations.  Homes have single phase supply, unless special (expensive) arrangements are made with the power company.

Answer 4

A 3 phase pump is more efficient than a single phase pump. It is also more powerful and more expensive.

Do you already have three phase power installed?

If not, check the cost of installing it.

Answer 5

Startup torque is better on 3-phase.

Answer 6

Billrussell's answer should give you what you were looking for - but for cost you should also consider where the pump is going to be installed and what sort of wiring and switchgear you'll need for the two systems.  One of 3-phase's advantages is that it can use smaller conductors.  (For a 2 HP motor there wouldn't likely be much savings in copper, unless it's being installed a long way from the transformer.)

Answer 7

3 phase motors are more efficient than single phase motors.

which means it draws less power, all other things being equal, and thus lower electric bill.

But a poorly designed 3 phase motor could be less efficient. Just check the specifications on each motor, they should list input power.

as to current, it depends on the voltages and where you measure the current. Power is what counts towards an electric bill.