VS pump consumption measurements, I'm getting a weird result

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266.4/367.2 = 72.5%, which is a pretty big power drop.

367.4 - 266.4 = 100.8 watts drop in power.

367.2/266.4 = 1.378 time more power at 1,500 rpm than at 1,600 rpm.

Definitely an unusual anomaly that cannot be explained by the current data available.

See if the filter pressure changes when the speed changes from 1,500 RPM to 1,600 RPM.

Also try the numbers going from highest speed down to the lowest speed.

Give the display a minute after changing speeds to see if the numbers are stable or if they fluctuate from the immediate change to the 1 minute mark.

Can you show a picture of the system?
 
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Here is my pump with what the drive display reports as power as well as the curve fit from the interpolated Energy Star Data which match fairly closely. I think the drive electronics power are included and it seems to level out at 25 watts.

But there is no bump either in the curve.


1718647000520.png

docs.google.com

Pump Database

PumpData Model,Manufacture,RPM,GPMb,GPMa,GPMc,WATTb,WATTa,WATTc,RPMl,GPMbl,GPMal,GPMcl,WATTbl,WATTal,WATTcl,THP,NHP,HHP,WEFa Energy Advantage Variable EAPVS2,Advanced,3450,40.00,67.00,88.00,1813.00,2114.00,2355.00,1725.00,20.00,34.00,44.00,275.00,312.00,343.00,3.00,3.00,1.00,6.00 Quiet Flo Varia...
docs.google.com docs.google.com
 
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First of all, thank you all. I wasn't expecting so much responses and I'm learning a lot \o/

JamesW said:
Theory is nice, but I would want to see actual True Power (Watts), Apparent Power (Volt-Amps) and Power Factor Measured for the drive input power and the drive output power at different speeds.

Also, I would want to see Vacuum and Discharge Pressure measurements and flow measurements for different speeds.
Click to expand...
Unfortunately, with my equipment I can only measure the apparent power, not the true one. I don't have any flowmeter as well. Apparent power is what I'm billed against right?

JamesW said:
Definitely an unusual anomaly that cannot be explained by the current data available.
See if the filter pressure changes when the speed changes from 1,500 RPM to 1,600 RPM.
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Pressure at the filter is around 3PSI. Resolution isn't great at these speeds, so can't see a pressure change when going from 1500 to 1600 rpm.

JamesW said:
Also try the numbers going from highest speed down to the lowest speed.
Click to expand...
I've tried that, and I get more or less the same results. Only difference being the wattage change anomaly occurs closer to 1600 rpm when going from lowest to highest speed, and closer to 1500 rpm when going from highest to lowest.

JamesW said:
Can you show a picture of the system?
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System is old (apart from the pump) and simple :)
Pulling from skimmer => pump => filter => gas heater (turned off) => pushing to Pool + Spa (the spa overflows into the pool). Here are some pictures:

IMG_7345.jpegIMG_7346.jpeg
IMG_7347.jpegIMG_7348.jpeg
 
mas985 said:
I cap at 90%. The chart only goes to 90%.
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For a 1.65 hp pump, your power use seems low.

The OP's power use seems more as expected.

As far as the drop at 1,500 rpm to 1,600 rpm, there does not seem to be any obvious explanation.

Maybe get a meter that can measure the true power and power factor.
1718649663241.png

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1718649624990.png
 
My plumbing curve is better than Curve C or 0.00786. Measure suction and pressure on full speed to get this value. You can see the calculations done here:

docs.google.com

Pool Pump Tools v028

docs.google.com docs.google.com

In fact, in the other sheets, it shows other calculations using other methods and they all come out about same. Even the full head calculation version in the "Head" Tab.

Energy Star at full speed for Curve C is 938 watts

My system at full speed is 941 watts

You can't use THP to predict energy use. It is a rating, not usage and some motors are oversized for the impeller.
 

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Pierrot said:
It's a WhisperFlo 1.5HP.
Click to expand...
The WhisperFlo VST has a total of 2.6 HP.

011533 2.6 115/208-230 V 1.64 13.9/11.1-10.1 A 8.4


1718652338156.png

1718652433457.png
www.pentair.com

WhisperFlo® VST Variable Speed Pool Pump

The WhisperFlo® VST Variable Speed Pump offers high quality, dependability, performance, and energy savings you can expect from variable speed pumps.
www.pentair.com www.pentair.com
 

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JamesW said:
941 watts is an input rating, which corresponds to about 0.941 HP load rating.
Click to expand...
Only if the motor efficiency is running at 74.57%. That would be typical of an induction motor. The efficiency of a VS motor is much higher than that. Pentair advertises a motor efficiency of 92% at full speed and drops to 90% at lower speeds for the Intelliflo. Most VS motors that use permanent magnet rotors should be in that range.

  • Electrical Horsepower (EHP) = Input Watts / 745.7 = Volts * Amps * Power Factor / 745.7 - Electrical power input delivered to the motor.
  • Brake Horsepower (BHP) = EHP * Motor Efficiency - Power delivered by the motor shaft to the impeller. This is not the same as THP or SFHP. BHP is a function of the load on the motor shaft and will change with Head, GPM and RPM.
  • Hydraulic HP (HHP) = BHP * Pumping Efficiency = Head (ft) * GPM / 3960 - Power delivered to the water. Sometimes called water HP (WHP) or pumping HP (PHP).
Click to expand...

EHP = 941 / 745.7 = 1.26
BHP = EHP * 0.9 = 1.13
HHP = 35 * 67 / 3960 = 0.59

In reality, these should actually be listed in reverse order because is it the HHP which determines BHP which determines EHP.

JamesW said:
Pool Pump and Motor ratings are load rating, not input ratings.
Click to expand...
Correct, I don't believe I said differently did I? I just said that you should not use THP to determine input power because the wet end design could be underloading the motor so it may not be a true reflection of input power. However, if you know an accurate motor efficiency, you can use THP with motor efficiency to come up with an upper bound of input power.

JamesW said:
A 1.65 HP pump/motor has a load of about 1230 watts and requires about 1,650 watts input.
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Only if it is loaded to rating and the efficiency of the motor is 74.57%. The fact is that many pumps are run well below full load due to the operating point on head curve.
 
1.65 hp is 1,230 watts.

So, even if the pump is 100% efficient, the power input should be at least 1,230 watts at full speed.

You are not going to get 100% efficiency from wire to water as shown in the below graph.

The below pump does not even hit 60% at maximum efficiency.

Also, the power factor is not going to be 1.00; it will be lower than 1.00.

1718663857757.png
 

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