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Can anyone explain why an electric motor on a water pump will pump the same amount of water with less wattage when it is wired for 220 rather than 110?

Wattage should be the same,Amprerage is different

jimmy

Th wattage (power) is the almost the same. Power =current x voltage. At 220V the current is about half of what it is at 110V. 220V will give a smidge more power because of reduced resistive loss ( I^2 xR) due to the smaller current.

You need to clarify:

How much less Wattage?

Did you measure this, or are you asking about something you heard?

Are you sure you don't mean Amps?

I do not remember the equation but 110 or 220 will use pretty much the same watts but 110 uses twice the amps so if you use 110 you need a heavier wire but if you use 220 the motor draws less amps

You got it right. More amps = more heat. The heat is wasted energy that doesn't pump water. In the previous post I got bashed when I said double the voltage & amps are half. Seems to be a double standard around here.

And reduced eddy currents. Jim

You have to have a thick skin to post on these forums. There are folks that get their panty hose in a knot if they don"t agree or if you make an honest mistake. Life"s too short to take this stuff that seriously.

I have a hard time understanding how to get more amps out of a 12 volt cell that is only half as big as the 6 it replaces. But that seems to be the norm here.

Hang in there Teddy, you got it basically right, I wasnt aware of the previoius discussion you mentioned. In a world of perfect zero resistance and perfect magnetic property conductors (doesnt exist) wattage would remain the same and as voltage increases current therefore decreases YET VOLTS X AMPS (Watts) is the same (or very close subject to heat and magnetic losses etc).

HOWEVER energy isnt created or destroyed ITS ONLY CHANGED IN FORM when you change electrical energy into rotational mechanical motor energy (its HP is a function of Torque x RPM) and anytime you pass current through a non zero resistance conductor some of the energy gets dissipated in the form of heat THAT DOESNT GO INTO CREATING MOTOR HP. That being said, if youre passing less current there less I Squared R wasted heat energy so the whole conversion/operation (electrical energy into mechaical) can be a bit more efficient at higher voltages.

NOTE HOWEVER its not quite that simple since in many AC motors the run windings are simply wired in series for 240 volt operation but paralell for 120 so theres still some current through all that wire.

ALSO as my friend Jim notes eddy currents use up some energy and waste it as heat and thats another factor in this discussion. Thats why magnetic cores in coils etc are laminated which reduces that problem to some extent.

ALSO a motor is mostly an inductive load with a lousy power factor which corrective counterbalancing capacitance can inprove and that also plays a part in this discussion

Sooooooooo some things may not be quite as simple as they first appear to a person unfamilar with all this electrical stuff AND IM LONG RETIRED AND RUSTY ON ALL THIS MYSELF so no warranty lol

John T

You are RIGHT some here get bent all out of shape if another person posts an opinion or an experience that differs from theirs HEAVEN FORBID SOMEONE DARE HAVE A DIFFERENT OPINION LOL

John T NOTE the above is my opinion only feel free to have a different one, I will respect yours and ask you extend me the same courtesy

Any given set of plates in a battery cell, if assumed to have the same exposed surface area and chemistry, will produce the same amp output into the same apparent load.
A 6 volt arrangement will produce the same Watts of output as the same area of 12 volt arrangement. (each into a load that draws that wattage) The theortetical amps will be twice as much in a 6 volt battery to produce the same watts (power). Thus the need for fatter cables in a 6v system. Jim

Lower current (amps) = less resistance losses in the wires leading to the motor for the same size wires. Could also be the motor design is more efficient on 220, lower winding resistance losses, etc.

That's a good question to ask a motor manufacturer.

Thanks for the reply to both John T and Jim. I was saying in my previous post that the magnetic field comes from the voltage & not the current. A 6 volt battery produces more amps than a 12 of the same size. So why doesn't the starter turn the engine over faster if the current makes the field???????????????????????

All other things being equal, the motor will pump EXACTLY the same amount of water and consume EXACTLY the same amount of energy at 120 as at 240. For all intents and purposes, the motor DOES NOT KNOW whether it's wired for 120 or 240. The current through its windings is IDENTICAL at either voltage. The only difference is whether the windings are connected in series or in parallel. If wired for 120, the motor draws twice as much current from its service as it does at 240. But the current through its windings is exactly the same.

Now, I did make the caveat of "all other things being equal". That is to say, the wiring that connects the motor to its service must be able to provide minimal voltage drop in either case. Typically there is significantly more voltage drop on a 120 circuit than a 240 circuit because the current is greater while the wire gauge is usually the same. As voltage drops, the motor draws more current to compensate, which further increases the voltage drop. But as long as the wire gauge of the 120 service is sufficiently big, voltage drop is minimal and there is no real difference to power consumption.

Two more comments:

First, the EFFICIENCY of the motor is measured AT THE MOTOR. Just because the motor is drawing more current doesn't make it less efficient. Now, power is lost due to voltage drop in the service, BUT YOU DON'T GET TO COUNT THAT AGAINST THE MOTOR'S EFFICIENCY. Overall efficiency, yes. Motor efficiency, no.

Also, the response of AC and DC motors to voltage drop is quite different. (Brush-type AC motors are actually DC motors, BTW.) A DC motor will run slower, draw less current and produce less power as voltage decreases. An AC motor will try to keep running at the same speed as voltage decreases, so it will draw more current and maintain nearly constant power. Note that the motor's output torque is determined by its LOAD, not by the motor, so the power will remain almost constant until the motor stalls out.

Well I just called the local power coop this AM. He agreed with me that a motor will pump the same amount of water on less wattage at 220 than 110. This has been common knowledge around here since the 60's when I first heard it. Maybe longer than that. Higher amps = more heat= energy lost. Voltage makes the field, not amps. When there is a line loss of voltage, the motor slows down, amps goes up & burns out the windings. If the field comes from the amps, why doesn't it pick up the speed & load & get on with it instead of burning the windings?

It is because the magnetic field comes from the voltage, & not the amps.

One amp is 6.241 × 10 to the 18th electrons passing one point in one second.
One volt pushes one amp through a circuit with one oh, of resistance.
Starter motors have tenths of an ohm of resistance.
Thus hundreds of amps.
Twelve volts can push twice as many electrons through the same resistance.
Some batteries can deliver massive short circuit amps, others do not.
A battery is limited by its delivery ability and total amp/hour capacity.
12v batteries can deliver dramatic current 1100cca
6 v batteries of similar design can as well, but if connected to a starter motor, the 12 will drive far more current into it. Jim

I'm sure the "expert" you spoke to would say anything to get you off the phone.

You have four guys here, all of whom have degrees on their walls saying they know what they're talking about, whom you're unwilling to believe because it conflicts with what you would LIKE to believe.

Let's take your argument to its logical extreme:
"voltage makes the field, not amps". OK, then take your dykes and cut the field winding. You will have full supply voltage and zero amps. How fast does the motor turn? How much torque does it produce? Even Crackpot Joe won't try to claim it's producing any power; anyway you look at it, zero torque times zero rpm equals zero horsepower.

Only a fool would expect an open curcuit to do anything.I have been load testing batteries and troubleshooting starters for over 40 years. As soon as the voltage drops, the starter slows down. Put a load tester on the battery & it will show more amps at 10 volts than at 11. Yet it is turning faster at 11 volts. If the magnetic field comes from the amps, Why doesn't it turn faster at 10 volts which has higher amps??????????????

How quickly you abandon your theory. It is said that a theory is never truly proven, as all it takes is one example where the theory fails to disprove it. Your theory is, paraphrased, "magnetic field strength is proportional to voltage and is not related to current". I simply tested one specific case: zero current, with non-zero voltage. Your theory fails.

To prove anything with your various tests, you need to simultaneously monitor current, voltage, speed and torque. current times voltage equals power in, speed times torque equals power out. I have no idea how you claim to have performed your test, but I seriously doubt it was instrumented in such a way that that you can prove your point. Did you maintain constant torque on the motor using a dynamometer? Did you record the current and voltage versus time using an oscilloscope?

The behavior of dc motors is very well understood. The no-load speed of a motor increases with voltage. The torque of a motor is proportion to the current through the motor. volts times current equals power in. torque times speed equals power out.