Over correction

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mivey said:
Removing splinters from the old lady's head?:p
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Not sure I follow you.
But I've been doing motor performance calculations for over forty years.
Often, I've had to provide NNT guaranteed performance figures with swingeing financial penalties for getting it wrong. Penalties that could and would negate any profit margin on the project.
So, getting it wrong wasn't an option.
 
Besoeker, "..I've been doing motor performance calculations for over forty years"

Well I've been doing it over 60 years! Maybe I learned a fact or 2 more than you!

FYI, check Stds for the case when a motor's terminal voltage 10% above nominal rating!

Phil
 
Phil Corso said:
Besoeker, "..I've been doing motor performance calculations for over forty years"

Well I've been doing it over 60 years! Maybe I learned a fact or 2 more than you!

FYI, check Stds for the case when a motor's terminal voltage 10% above nominal rating!

Phil
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It's very simple. Load it more, it slips more.
 
Phil Corso said:
Besoeker, "..I've been doing motor performance calculations for over forty years"

Well I've been doing it over 60 years! Maybe I learned a fact or 2 more than you!
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And maybe not. Then, given your obviously advanced years maybe, just maybe, you could have forgotten a few.

Do you use the Steinmetz equivalent circuit?
And have you had to guarantee NNT performance with the potential of iniquitous financial penalties for getting it wrong?
 
In my experience when two respected experts in the same field get widely differing results the discrepancy usually results from mismatched assumptions and conditions going in.
 
GoldDigger said:
In my experience when two respected experts in the same field get widely differing results the discrepancy usually results from mismatched assumptions and conditions going in.
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My results have financial consequences. Getting them wrong is not an option.

Here are the results for a 625kW motor driving a pump.
It was tested in what is commonly called a string test with all sorts of things subject to calibrated measurements including a final "wire to water" test.

It clearly refutes Phil's claims. Up to you which you believe of course but I've had to put my money where my mouth is.

http://i36.photobucket.com/albums/e39/Besoeker/625kW%2003_zpshb8lcuem.jpg
 
Besoeker...

An emphatic, YES, to both your questions! But, I certainly don't want to start a PEing contest!

Regarding your 'advanced years' comment... I find that the only thing wrong about being eighty, is to learn that it's 2 forties!

And, lots to of luck to you, too!

BTW, want my resume?
 
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So if we have increased speed we pump water faster. If filling a tank that mostly just means it is filled faster, net energy used may remain about the same.

Where this may get more complex is for something like the OP's application for irrigation pumping.

Pumping the water faster without notifying the farmer may throw off some of what he has figured out. With center pivot or lateral moving irrigation machines they calculate how much water is being applied by knowing flow rates and travel speed. They adjust travel speed to regulate how much water is applied.

To further complicate things they also sometimes inject fertilizer, pesticides, etc. into the water. Not knowing there is a change in how much water is being applied throws those calculations off as they adjust flow rates of the injection system to get desired application - as well as set travel speed of the center pivot or lateral moving machine according to flow rates.
 
kwired said:
So if we have increased speed we pump water faster. If filling a tank that mostly just means it is filled faster, net energy used may remain about the same.
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I agree. But, for a cage induction motor, the faster is a bit of a red herring in most cases. To all intents and purposes it is fixed speed give or take a very small margin.
 
Besoeker...

Why don't you use the your expertise and model to disprove the conclusions I reached in my example?

Phil

FEI,
Here's another helpful study to those that will get older! A study of some 50-60,000 residents in a large senior-citizen's community was conducted to determine what those that attained the age of 80 and 90 had in common! Anyone interested in the outcome?
 
kwired said:
So if we have increased speed we pump water faster. If filling a tank that mostly just means it is filled faster, net energy used may remain about the same.

Where this may get more complex is for something like the OP's application for irrigation pumping.

Pumping the water faster without notifying the farmer may throw off some of what he has figured out. With center pivot or lateral moving irrigation machines they calculate how much water is being applied by knowing flow rates and travel speed. They adjust travel speed to regulate how much water is applied.

To further complicate things they also sometimes inject fertilizer, pesticides, etc. into the water. Not knowing there is a change in how much water is being applied throws those calculations off as they adjust flow rates of the injection system to get desired application - as well as set travel speed of the center pivot or lateral moving machine according to flow rates.
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FWIW, this one is pipe. Increased speed to me means more GPM or PSI, no mater how small. Both result in more work being done.
 
ptonsparky said:
FWIW, this one is pipe. Increased speed to me means more GPM or PSI, no mater how small. Both result in more work being done.
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That holds true if there is no flow controller at the pump's discharge piping. If there is one, the controller will surely respond to clip the change in flow-->the shaft power requirement remains the same.
 
ptonsparky said:
FWIW, this one is pipe. Increased speed to me means more GPM or PSI, no mater how small. Both result in more work being done.
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A cage motor is, to all intents and purposes, a fixed speed machine. The more speed argument is an irrelevance.
 
Besoeker... Let's bury the hatchet.

The answer is staring you in the face. I will prove my point using the parameters of your speed-torque curve. And, all I need are the parameters used in your Steinmetz Model! Are you agreeable?

Phil
 
Phil Corso said:
Besoeker... Let's bury the hatchet.

The answer is staring you in the face. I will prove my point using the parameters of your speed-torque curve. And, all I need are the parameters used in your Steinmetz Model! Are you agreeable?

Phil
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No hatchet from me, sunshine. No animosity on my part.
As my results clearly show, more slip, more torque, more output power. It really is that simple.

However, here is the raw data used to get those results since you are evidently not prepared to cite your own.

http://i36.photobucket.com/albums/e39/Besoeker/Cage motor data 01_zpsovakzmkd.jpg
 
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