- Location
- Massachusetts
Why not post what 'affinity law' you feel I have broken?
Power factor correction experiment
- Thread starter gar
- Start date
- Status
Why not post what 'affinity law' you feel I have broken?
That's line voltage, not motor voltage.
Look again at the title.
Reduced Motor Voltage.....
Bit of a clue there, don't you think?
You would expect the voltage to be marginally higher is save mode because the current is is less resulting reduced line voltage drop.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
111116-1411 EST
Instead of trying to refine my experiment with the capacitors I used in post #1 I have now ordered one of the commercial units claiming big power savings.
I did not want to disclose much information so my questions were limited.
The company I ordered from has a current special price of essentially $100 including shipping. This apparently results from another company advertizing a similar price.
This company, KVAR, has two residential models. One is a -1050 and the other -1200. I asked what was the difference since both have the same price. The answer was a different amount of capacitance. This makes no sense to price them the same. Then I ask what was the capacitance? The answer --- proprietary. What nonsense. Any competitor would have no problem determining what was in the box.
How they determine which unit is correct for you is based on the size of your electric bill. $170 is the transition point. Since I do run $200 a month on rare occasions I gave them that figure to convince them I should get the higher capacitance unit. My guess is this will have two 40 ufd capacitors.
They seem to guarantee you a 6% saving. I have to see what the fine print says when I get the unit. I have no plans to confront them with proof of what it does. It is a useful capacitor to have sitting around for whatever I might do with it.
I just need a real device marketed for for the scam so that no one can claim that what I used for the test was somehow different from what is being sold.
.
Instead of trying to refine my experiment with the capacitors I used in post #1 I have now ordered one of the commercial units claiming big power savings.
I did not want to disclose much information so my questions were limited.
The company I ordered from has a current special price of essentially $100 including shipping. This apparently results from another company advertizing a similar price.
This company, KVAR, has two residential models. One is a -1050 and the other -1200. I asked what was the difference since both have the same price. The answer was a different amount of capacitance. This makes no sense to price them the same. Then I ask what was the capacitance? The answer --- proprietary. What nonsense. Any competitor would have no problem determining what was in the box.
How they determine which unit is correct for you is based on the size of your electric bill. $170 is the transition point. Since I do run $200 a month on rare occasions I gave them that figure to convince them I should get the higher capacitance unit. My guess is this will have two 40 ufd capacitors.
They seem to guarantee you a 6% saving. I have to see what the fine print says when I get the unit. I have no plans to confront them with proof of what it does. It is a useful capacitor to have sitting around for whatever I might do with it.
I just need a real device marketed for for the scam so that no one can claim that what I used for the test was somehow different from what is being sold.
.
Hi Gar
The tests I did and the results were for a commercially available unit.
I think one of the issues is that when someone buys into energy savings they just might take a greater interest in how they use energy and save as a result of that.
The unit, whilst not saving energy, might be the catalyst that makes the user do that.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
111116-1541 EST
Besoeker:
I think your analysis is likely a big factor.
I am also thinking that since the light bulb transition is underway and that homeowners are buying new appliances that this may contribute to a 6% reduction in addition to what you are suggesting.
Some of my ancestors are from England. If we can make a connection in one path around the late 1700s, then this path leads to a person in about 1050. After about 1300 it is surprising how many individuals lived into their 80s or 90s.
.
Besoeker:
I think your analysis is likely a big factor.
I am also thinking that since the light bulb transition is underway and that homeowners are buying new appliances that this may contribute to a 6% reduction in addition to what you are suggesting.
Some of my ancestors are from England. If we can make a connection in one path around the late 1700s, then this path leads to a person in about 1050. After about 1300 it is surprising how many individuals lived into their 80s or 90s.
.
Yes, very good point.
Not sure where you were going with this.
I'm not from England and, as far as I have been able to ascertain, none of my ancestors back to around 1745 were either. Before that, I don't know.
I take your point about people who lived to a good age. I read something about this a while back. Average life expectancy was low but I think this was, to some extent, as a result of those who didn't make it much beyond birth or succumbed to childhood diseases. Those who got beyond that, had better prospects.
- Location
- Massachusetts
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
You rock.
10-4 on that. Gar, you da man. :thumbsup:
I want toys these EEs get.
Best I can do is that Santa says I may get a Fluke T-179 for Xmas.
10-4 on that. Gar, you da man. :thumbsup:
I want toys these EEs get.
Best I can do is that Santa says I may get a Fluke T-179 for Xmas.
When I was much younger, I got a Heathkit VTVM. Still have it.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
When I go trolling it is in the boat, with a rod and reel in hand I guess the idea is to deceive the fish into taking the bait I put out as a meal
mivey
Senior Member
Oh no! Now you are breaking laws and physics! What is the world coming to?
mivey
Senior Member
Aren't they limited to a constant efficiency assumption or something like that (I do not feel like looking it up)?
T
T.M.Haja Sahib
Guest
You are correct.It is line voltage not motor voltage.But the current is also line current and not motor current.Unfortunately,motor voltages and motor currents were not displayed.
T
T.M.Haja Sahib
Guest
Your assumption that water output remains the same when voltage is reduced across the pump motor contradicts the pump affinity law:
Pump motor brake horse power at reduced voltage = Cube of Pump RPM at reduced voltage
Pump motor brake horse power at nominal voltage Cube of Pump RPM at nominal voltage
Attachments
Last edited:
- Location
- Massachusetts
- Location
- Massachusetts
You are either trolling, or there is a language barrier or you are just don't understand the subject.
- Location
- Massachusetts
That would be great if the electric motor efficiency was constant.
You must have missed the point I made in post #118.
For the cage motors I've dealt with, slip is generally 1% or less at rated load. To check, I looked at a pumping project we did with three 4-pole machines. Speed at rated power is 1493 rpm and, like yourselves, our supply frequency is 50Hz. You will thus deduce have no difficulty in deducing that slip in this case is below 0.5%. Voltage optimisation is generally deployed when the motor is running at lower that rated load meaning that slip is even lower. To take as an example the machine I cited, going from say 3/4 to 1/1 slip would result in a speed difference of about 0.1%. That's all. From my experience, and we do a fair bit in the water industry, measuring head or flow, far less their product*, to that level of accuracy would be a challenge.
I don't disagree with the curve you submitted but it relates to variable speed operation. Here we are looking at a fixed speed application.
*pump power is head times flow
T
T.M.Haja Sahib
Guest
Your one line retorts are more often vague than clear.Why can't you explain a bit how I am wrong?
T
T.M.Haja Sahib
Guest
I want that your knowledge on pumps in general and those affinity laws in particular see some improvement if possible at all.For that purpose I provide a link below especially for you.
http://www.pdhonline.org/courses/m125/m125content.pdf
- Status