Power usage of submersable pump

[Ludington]

Let's see if someone knows this answer....
I have a 2 wire submersible pump. So it's generally on or off from a 40/ 60 pressure switch.
I measure 1 leg of the 220 that feeds it, and the app will double it to get watts used.
My pump has a voltage draw that doesn't make sense to me. It starts low, jumps up, then drops again over roughly 3 minutes. I can see the low draw at first but not the low at the end, especially with just a standard on/off switch. Any idea why it would do this ? Pump is roughly a year old, but has always done this. Attached is a graph pic of kw over time.
The pressure guage will show a steady increase in pressure if you watch it.

 

[Valveman]

What pump do you have?

 

[Ludington]

It's a countryline 1/2 hp, 220 , 2 wire. And running water this morning and watching what it does.. it runs at the low watts for exactly 1 minute, then on higher wattage until it gets to 1 minute before shutting down and then on lower watts for 1 minute. It just seems odd to me. But exactly 1 minute before and after .

 

[Ludington]

I just found that the app (Emporia energy) that I use to monitor with has changed thier method.
They are averaging the data recieved during the first whole minute and the last whole minute. So it makes it look like the first and last minute are lower than what it's actually using.
I told them that it was unacceptable , there is no way to watch for spikes or dips in that first and last minute. That could be a sign of something starting to fail.
So, nothing wrong with my pump. Just a bad app. I may have to look for something else.

 

[RS]

As the pressure increases the motor load drops, because it's not moving as much water, if you were to deadhead it the wattage would drop more. That is one of the selling points of a cycle-stop valve that Valveman sells.

 

[RS]

After googling this subject I'm not so sure I'm correct, I will be watching for other comments! Then I will take a sump pump and my Kill-o-watt and do an actual test!

 

[Ludington]

After googling this subject I'm not so sure I'm correct, I will be watching for other comments! Then I will take a sump pump and my Kill-o-watt and do an actual test!

Did you see I found the .problem ? It's the emporia energy measuring system / app that's screwed up. They changed how they store and display the data.
Thier minute, day,month ,year data is fine... it's just the seconds data they screwed with. And if your trying to see if your appliances are spiking, or dipping in power, it's worthless.. (unless you can catch it and watch it live while it happens... then they display the actual data)

 

[Valveman]

Did you see I found the .problem ? It's the emporia energy measuring system / app that's screwed up. They changed how they store and display the data.
Thier minute, day,month ,year data is fine... it's just the seconds data they screwed with. And if your trying to see if your appliances are spiking, or dipping in power, it's worthless.. (unless you can catch it and watch it live while it happens... then they display the actual data)

I agree. You need to see the spikes and dips. That type/size pump should start with a quick peak of 30 amps or so, level out quickly at about 5 amps. Maybe drop to 4.5 amps as the tank is filling, and then zero amps as soon as the pump shuts off. The 1 minute timing clued me to it being averaged somehow.

 

[Ludington]

I agree. You need to see the spikes and dips. That type/size pump should start with a quick peak of 30 amps or so, level out quickly at about 5 amps. Maybe drop to 4.5 amps as the tank is filling, and then zero amps as soon as the pump shuts off. The 1 minute timing clued me to it being averaged somehow.

Yes, I talked with emporia, and they said that was what they were doing. I told them it was unacceptable. But I don't think they care.

 

[RS]

I did my experiment, using a Kill-a-watt and a 1/4 hp sump pump. A Kill-a-watt give instantaneous reading of Volts, watts, amps, and accumulated kwh. I just had a short 1/2 hose on the pump, so it was being restricted somewhat all the time. When it first started, after priming with an open hose it drew 292 watts, but within 20 seconds it slowly dropped to 276, and stabilized there. Then when I shut the hose off it dropped to 248, but the pump has a weep hole, so it was still moving some water. This confirms my thought, but there isn't as much change as I expected, but I think a well pump would change more.