Rewiring pool - 110v vs. 220v benefits?

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amissner
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Rewiring pool - 110v vs. 220v benefits?

Postby amissner » Tue 29 Dec, 2009 07:40

Heya. Looking for some advice. I am rewiring my pool to replace the timers and add freezing controls. The 1hp pump, Polaris and chlorine generator are currently wired for 110v. I have 220v service at the pool (not sure why it was wired 110v anyway), so the question is: What is the benefit, if any, of 220v vs. 110v for the pump, polaris and chlorine generator? Not sure I want to fool with changing it unless there is some tangible benefit.

On a related note, does anyone know of any freezing protection controls I can add to my existing mechanical pool timers? Seems like every one I have found is integrated into the timer.

Thanks.


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Rewiring pool - 110v vs. 220v benefits?

Postby czechmate » Tue 29 Dec, 2009 11:42

220 Volt wiring will require half the amperage. Not only trough your branch circuit wires but also through your motor windings. (Which in the 6-8 hour cycle and 115F sun prying in your motor takes a toll on it's lifespan).
220V wiring will need a 2 pole breaker 15-20A.
Breaker is there to protect the wiring, not the load. Motors are protected by internal thermal protection.
So 12AWG copper can use a max 20 Amp breaker and should not have more than 80% demand which is 16A.
It is more than sufficient to run any residential pump on 230-240V.
Your timer obviously has a clock currently on 110V.
Your timer contactor contacts are rated for 220V, but you will need an extra wire for the second phase to the clock and than to the motor, since the second wire to the motor is white which is against the code.
There is also this legal solution: Mark the white wire with black tape on all ends
about 2-3 inches and of course you will need to take it of the neutral bar in the panel and make it your second phase on this 2 pole breaker.
You will than need to replace your timer clock with 220V clock.
Than you are set to order a freeze-stat with 220V contactor coil.
I hope it is not too confusing.
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Rewiring pool - 110v vs. 220v benefits?

Postby czechmate » Tue 29 Dec, 2009 11:50

Obviously, the motor connection inside the each motor packerhead will have to be reconnected according to the wiring diagram. For 110V windings are parallel, for 230V they are in series to add resistance for higher voltage. If you forget this part, you will burn the windings in no time!
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Rewiring pool - 110v vs. 220v benefits?

Postby mas985 » Tue 29 Dec, 2009 21:59

There is actually very little difference between running a pump motor on 220v vs 110v. In the 110v configuration, the windings are in parallel which means the amperage is split between the windings while with 220v all of the amperage goes through both windings in a series configuration but the voltage is split between the windings. So in both cases, the voltage and the amperage ends up being exactly the same in the windings of the motor and the I2R loses are exactly the same and the heat generated in the windings is exactly the same. This is why the efficiency of the motor does not change with winding configuration nor does the pump life rating change with voltage feed. The voltage choices are more a matter of convience than efficiency. Also, higher HP motors will only accept 220v because they would require more than 15 amps with 110v and much larger wire gauge which makes wiring more difficult.

However, voltage drive of the motor does effect the loses in the house wiring so 220v tends to be a bit more efficient although if larger wire is used for 110v vs 220v as it should, then the loses can be mitigated there as well. But given the choice, I would always go with 220v unless it required a significant amount changes to the hardware.
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Rewiring pool - 110v vs. 220v benefits?

Postby czechmate » Tue 29 Dec, 2009 23:19

Now here is a guy that fully qualifies for" knowing just enough to be dangerous"! :D
Mr. "Mas985", on the contrary to your personal opinion, there is a quite a bit of a difference between 115V and 230V applied to the motor windings.
If the amperage was the same using either voltage as you claim, and a horsepower is a simple multiple of a current and voltage applied, how you maintain the same number (HP) when you drop from 230V to 115V??????? (It is called equation, from being equal).
There is no need to argue here.
Tomorrow, when the daylight will come around again, take a look at the faceplate on your motor.
(It may be the first time you saw it).
It will tell you the respective currents for both voltages.
The 230V will show exactly half the current.
Also, there is no such thing as life rating, Sir. I was referring to a life span.
Also, higher current does generate more heat in the same windings, that compounds with the outside temperature and affects the break down the shellac winding insulation.
Sir, this forums goal is to help pool owners to remedy their problems.
It is merely done by presenting facts, not a personal myths or someones poor knowledge on the subject.
At any rate, it is not a pissing contest and correcting me, by giving completely opposite, wrong advise on electrical question is pretty irresponsible.

BTW, I got my electrical degree 45 years ago, and probably forgot more, than you still hope to learn.
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Rewiring pool - 110v vs. 220v benefits?

Postby mas985 » Wed 30 Dec, 2009 01:14

czechmate,

You obviously didn't understand what I wrote, please read it again and please do not put words in my mouth. I NEVER said that the current on INPUT to the motor was the same for 230v vs 115v.

Yes obviously, the current at the INPUT to the motor is half for 230v vs 115v this I agree and I never suggested otherwise. In fact, I mentioned the impact on the house wiring because of this. But what I said was the current IN the individual windings within the motor itself was the same. There are 4 windings ( 2 poles x 2 windings each) connected in two different ways for 230v vs 115v. You even mentioned the series/parallel arrangement of the windings yourself in your post so I know you agree with at least this.

Perhaps a refresher on parallel and series circuits is in order:

A 115v feed has 2 sets of parallel windings where half of the total current goes to each winding and each winding has 115v across them. Parallel circuits divide current but have equal voltage across them.

A 230v feed has 2 sets of series windings so the total current goes through both windings and the voltage is split between the windings so each winding has 115v across them. Series circuits divide voltage but have equal current through them.

So even though 115v has twice the current going INTO the motor, it is split into two separate sets of windings within the motor and half the current going to each winding. However, the current in 230v which is half of 115v goes through both series windings so effectively it is the same current and voltage per winding for both 115v and 230v. Do you disagree with this? This is basic circuit theory so I certainly hope you do not.

As for experience, I may have ONLY 25 years but I do have a masters degree in electrical engineering so I have a bit of training in this area and I do understand motor theory quite well.

Oh, and BTW motors do have a life rating it is often refered to as MTBF or mean time between failures and it is the same for both voltages. It isn't always published by manufactures but they do exist.
Gavin r Wills

Rewiring pool - 110v vs. 220v benefits?

Postby Gavin r Wills » Wed 30 Dec, 2009 03:03

yeah i cop the same crap from checkmate when i try to help people out for free :crazy:
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Rewiring pool - 110v vs. 220v benefits?

Postby czechmate » Wed 30 Dec, 2009 06:49

mas985 wrote:So in both cases, the voltage and the amperage ends up being exactly the same in the windings of the motor and the I2R loses are exactly the same

Chap, no need to put words in your mouth. Here it is.
mas985 wrote:As for experience, I may have ONLY 25 years but I do have a masters degree in electrical engineering so I have a bit of training in this area and I do understand motor theory quite well.

Obviously, it takes some people longer to understand Ohms law.
Licence does not mean a thing.
There is also lot of drivers out there with a driver license, that can not park in parallel.
Have a nice day.
Ausie

Rewiring pool - 110v vs. 220v benefits?

Postby Ausie » Wed 30 Dec, 2009 08:19

mas985:
I would beg to differ with your following statement:
mas985 wrote:A 230v feed has 2 sets of series windings so the total current goes through both windings and the voltage is split between the windings so each winding has 115v across them. Series circuits divide voltage but have equal current through them.


1. In series connection voltage is applied across one continuous winding, therefore the voltage does not split!
2. There is no 115V applied to any sections of winding in high voltage connection. Period. (unless ofcourse you want to measure gradually measure voltage between point A and B, which gradually increases from 0 to 230V, as the resistance progresses.
3. There is only one set of windings - 4lead packerhead, with these pool motors, since only two voltages are available in residential and even commercial pools use the same source.

I though it deserved a clarification, since you seem to be a little confused how the voltage limits the currents. With horsepower being constant, current has to drop in half through the whole winding, when you double the voltage. Very simple fact.
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Rewiring pool - 110v vs. 220v benefits?

Postby mas985 » Wed 30 Dec, 2009 12:06

czechmate,

You are confusing windings with motor inputs. They are not the same. So this quote:

"So in both cases, the voltage and the amperage ends up being exactly the same in the windings of the motor and the I2R loses are exactly the same."

The key word is windings, I didn't say motor inputs. The individual windings within the motor will have the same voltage and current but the motor inputs will be different. A dual voltage motor splits the pole windings so they can be fed differently. You said it yourself in this statement:

czechmate wrote:Obviously, the motor connection inside the each motor packerhead will have to be reconnected according to the wiring diagram. For 110V windings are parallel, for 230V they are in series to add resistance for higher voltage. If you forget this part, you will burn the windings in no time!


I completely agree with this statement. However, when you have two windings in series and apply 230v across them, each individual winding will have 115v across it (115v + 115v = 230v) and the same current through it because they are in series. When you put those same two windings in parallel and put 115v across them, both windings will EACH have the same current as in the 230v case because the voltage is the same across each individual winding. However, the TOTAL current in the 115v case will be twice that as in the 230v case because it is fed with two windings in parallel.

If the windings are the same, then the complex impedance will be the same. The voltage across each winding segment is the same because of the series connection at 230v vs the parallel connection at 115v. So by Ohms law, the currents will be the same in each individual winding. But because the 115v case has two windings in parallel, current adds at connection nodes so the input to the motor will have twice the current as the 230v case.

So using ohms law (Generalized for winding impedance Z)

In the series case:

Is = Vs / (Z + Z) = Vs / 2Z where Vs = 230v rms

In the parallel case:

Ip = Vp / Z + Vp / Z = 2Vp / Z where Vp = 115v rms

So “Ip” is twice “Is” but the current in each segment of the winding, “Iw”, is the same.

Iw = Vp / Z = Vs / 2Z = Is


czechmate wrote:Obviously, it takes some people longer to understand Ohms law.
Licence does not mean a thing.
There is also lot of drivers out there with a driver license, that can not park in parallel.
Have a nice day.


Then why did you bring up your experience in the first place if it doesn't matter?


Aussie,

On #1 & #2, because you have 230v across two windings in series, if you measure the voltage across a single winding, it will be 115v. I never meant to imply that 115v was “applied” to each winding in the high voltage case only that there is 115v volts across each winding because they are in series.
As for #3, in a two pole split phase motor you must have at least four windings, one for each pole in the main windings and one for each pole in the starter winding. These windings are usually connected in series for the two poles of a 230v motor so they appear as two windings when in fact they are four winding fed in series pairs. With dual voltage, you have to be able to configure the windings in series for 230v and parallel for 115v volts. So the series connection between the poles is separated into two windings so they can be fed in parallel for 115v. This is why the motor needs to be reconfigured with jumpers when powered with different voltages.

This link and this link might be usedful as it illustrates how the windings are connected.
Mark
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Rewiring pool - 110v vs. 220v benefits?

Postby flipper-26 » Thu 31 Dec, 2009 23:09

only advantage is that the motor will run cooler via lower amps which will improve effiency of pump.
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Rewiring pool - 110v vs. 220v benefits?

Postby chem geek » Fri 01 Jan, 2010 02:51

flipper-26 wrote:only advantage is that the motor will run cooler via lower amps which will improve effiency of pump.

This is not true. Read mas985's (Mark's) posts again. The amount of power loss and thus heat (per time) generated through a resistive circuit is I2R where "I" is current (in amps) and "R" is resistance (in ohms; in an AC motor, it's really impedance, Z, that is used, but Ohm's Law, using complex numbers, still applies) and the power is in Watts. There are two windings in a dual-voltage motor where these windings are in parallel for 110V and in series for 220V (there is a manual switch one changes to select which configuration is used). If R is the resistance in each winding, then the resistive heat losses in each configuration are as follows (and yes, I'm ignoring AC impedance and capacitance for simplicity, but it doesn't change the conclusion on resistive losses which generate heat):

PARALLEL (110V applied externally)
Resistance of pump overall (ignoring load) = 1/(1/R+1/R) = 1/(2/R) = R/2
Current applied to pump overall = 110/(R/2) = 220/R
Voltage across each parallel winding = 110 (the voltage is the same across each winding)
Current in each parallel winding = 110/R (the current is split across each winding)
Resistive heat losses = 2*(110/R)2*R = 2*110*110/R = 220*110/R

SERIES (220V applied externally)
Resistance of pump overall (ignoring load) = R+R = 2*R
Current applied to pump overall = 220V/(2*R) = 110/R
Voltage across each series winding = 220/2 = 110 (the voltage drop is the same in each winding)
Current in each series winding = 110/R (all current flows through each winding)
Resistive heat losses = 2*(110/R)2*R = 2*110*110/R = 220*110/R
or equivalently
Voltage across both windings in series taken as a whole = 220
Resistance of both windings taken as a whole = R+R = 2*R
Current through both windings taken as a whole = 220/(2*R) = 110/R
Resistive heat losses = (110/R)2*(2*R) = 2*110*110/R = 220*110/R

The resistive heat losses are the same because the current is the same in each winding in the two cases because the voltage across each winding is the same. In the parallel 110V case, the overall current is split in half to each winding, but the overall current to the pump is twice that as in the series 220V case where the current in each winding is the same as the overall current.

Yet another way to look at this is that the resistance of the parallel circuit is 1/4th that of the series circuit. Since the parallel circuit (110V) has half the overall voltage of the series circuit (220V), the overall power (current times voltage, using RMS and ignoring phase) is the same in both cases because the parallel circuit has twice the current overall (split in half to each winding) but half the voltage of the series circuit.

As mas985 (Mark) noted, there IS a difference in current outside the pump (that is, in the wiring to the pump) so given the same gauge of wire one has less losses outside the pump with 220V, but typically the gauge of wire used is different for 110V vs. 220V. So either the outside losses will be less with 220V or the wiring will be less expensive (narrower gauge) or some intermediate combination, but heat losses (and heat generation) in the pump itself will be the same in each configuration (assuming 220V is applied with a series configuration while 110V is applied with a parallel configuration).

Richard
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Rewiring pool - 110v vs. 220v benefits?

Postby czechmate » Sat 02 Jan, 2010 06:39

chem geek wrote:There are two windings in a dual-voltage motor where these windings are in parallel for 110V and in series for 220V (there is a manual switch one changes to select which configuration is used).

Just for a clarification.
There is no manual switch incorporated in the packer head of any pool pump motor, to change winding configuration.
Not even in the packer head of a three phase 480V or European Delta/Wye.
It is always done by hardwire make-up or a use of jumper configuration in a commercial motors.
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Rewiring pool - 110v vs. 220v benefits?

Postby chem geek » Sat 02 Jan, 2010 13:15

czechmate wrote:Obviously, the motor connection inside the each motor packerhead will have to be reconnected according to the wiring diagram. For 110V windings are parallel, for 230V they are in series to add resistance for higher voltage. If you forget this part, you will burn the windings in no time!

OK, so it's either a jumper or a reconnection (instead of a physical switch, by which I meant you had to do something physically to change the connection from series to parallel or vice versa -- it doesn't have to be an actual toggle or rotating switch and I should have written "manually reconfigure").

That doesn't change the physics as outlined in the post above. The bottom line is that the series case (220V) has 4 times the overall resistance (impedance) of the parallel case (110V), but has twice the voltage, so the overall current is half; so the parallel case has twice the current entering the motor as the series case. However, the parallel case (110V) has this current split into two (i.e. cut in half) to each winding. So the current going through each winding is the same as that in the series case.

With the same current going through each winding in both parallel and series configurations, please explain how the I2R losses are different.

Also, the series configuration with 220V input is twice the voltage of the parallel configuration with 110V, but has half the current going into the pump so the product of voltage times current (i.e. power) is the same as that of the parallel configuration with 110V. With the same power going into the pump, how is it that the resistive losses are different, given the conservation of energy?
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Rewiring pool - 110v vs. 220v benefits?

Postby chem geek » Thu 21 Jan, 2010 22:45

I received some further clarification from czechmate. The real-world practical experience has shown that 120V configurations failed more than 220V and failures are mostly electrical, not mechanical. The wire and connections before the split to two windings clearly have twice the current and associated higher heat and this is a particular problem on wire nuts with #12 and small stranded winding wires. He also found that locked rotor currents thru windings were higher with the 120V configuration (though probably not 2x as we showed shouldn't happen).

So, unfortunately, our discussion in this thread diverted to the single focus of theoretical current in a parallel split winding situation and missed the real issue of problems with twice as much current before the parallel winding split (in the motor -- we did talk about such currents outside the motor) and the real-world higher current in the windings (still unexplained unless the two winding configuration has overall lower impedance for some reason drawing more power overall into the motor or perhaps the split is uneven in resistance causing one winding to be higher in current -- this is speculation on my part).

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