Power factor correction experiment

[Besoeker]

Please refer to your post #5,wherein you recorded additional objection

Yes, but the simple objection is on the basis of cost.
The problem with the distorted waveforms is secondary or actually irrelevant if you didn't waste your money on it in the first place.
You claim that my objection to installation of a PFC capacitor in a residence is still not supported simply doesn't hold water.
I presented actual waveforms of what happened. Real time, real measurements. What better could you get?

At residential level??????

Yes.Do not get intimidated by MVA's.The residence is also connected to the grid.

Why would you even contemplate that I might be?
I routinely deal with equipment in the MW range. It just isn't physically in my house. Using units of MVAr simply isn't appropriate.
Perhaps you missed my point.

No.I acknowledged your expertise

You seem to have an odd way of doing that.
"Again,you seem to have no idea of why harmonic analysis was required""
"It appears you have misconceptions"

and requested you to apply it in the case of a residence.

Why, when I have already given actual measurements?
As I indicated in post #29, calculations are useful in determining the probable outcome.
Measurements give you the actual outcome.

 

[Jraef]

I believe this thread is officially...

 

[T.M.Haja Sahib]

I presented actual waveforms of what happened. Real time, real measurements. What better could you get?

It does not reveal whether resonance is taking place or not.

It just isn't physically in my house. Using units of MVAr simply isn't appropriate.
Perhaps you missed my point.

No.You would be right if only integral MVAr's are required to be used in the formula.But really fractional values are also permitted.

You seem to have an odd way of doing that.
"Again,you seem to have no idea of why harmonic analysis was required""
"It appears you have misconceptions"

I already told it is a friendly discussion.

Why, when I have already given actual measurements?
As I indicated in post #29, calculations are useful in determining the probable outcome.
Measurements give you the actual outcome.

I could not determine from your post(s)whether the capacitor is causing the distortion,because you did not show which harmonic is in resonance.

 

[T.M.Haja Sahib]

I _LOVE_ the way you think, mivey. I think I'll brainstorm a little ...

ASSUME
2 kW
200V
200 ft from panel to motor
20A@0.5 pf uncorrected
10A@1.0 pf perfectly corrected, perfect capacitor
#10 wire, 0.4 ohm loop
drop@10A, 4V, 2%
drop@20A, 8V, 4%
reduced voltage drop 4V, reduced current 10A

These are REDUCTIONS ...
P=I*I*R=10*10*0.4=40W
crosscheck, P=E*E/R=4*4/0.4=40W

ASSUME 2.5 hours a day (probably high for a residential water pump), 100Wh/day
at the assumed $0.10/kWh, save a penny a day, on the order of $4 a year. With a real capacitor, it'll be less. With real PFs, it'll PROBABLY be less; full load PF for a 2.2kW single phase motor I picked at random from Baldor's website is 0.87, so MUCH less. Mivey's $1.00 a year looks REALLY reasonable as a SWAG.

My electrician will charge for the capacitor and installation ... REALLY hard to get reasonable payback.

The improved voltage profile at the motor due to connection of suitable capacitor across the motor can enhance the working life of the pump motor.The saving possible due to this should also be taken into account for calculating the payback period.

 

[T.M.Haja Sahib]

You seem to be the only one who is talking about that case - it is not the point of the thread. See my post #23:

http://forums.mikeholt.com/showthread.php?t=140830&p=1347580#post1347580

I introduced this into the thread because gar stated in the OP that his aim was towards a study of energy conservation.

 

[Besoeker]

It does not reveal whether resonance is taking place or not.

It is what it is. EOS.

No.You would be right if only integral MVAr's are required to be used in the formula.But really fractional values are also permitted.

Yes. The point is that MVAr for PFC in the context of a residence is an inappropriate unit.

I already told it is a friendly discussion.

"Again,you seem to have no idea of why harmonic analysis was required"
"It appears you have misconceptions"
don't actually come across as very friendly.
Indeed they cast aspersions on my intellectual capacity and my capability as an electrical engineer.
I don't see any way in which such comments can be construed as friendly.
If you see it otherwise, that's fine.

I could not determine from your post(s)whether the capacitor is causing the distortion,

I gave waveforms with and without the capacitor connected. I should have thought it abundantly obvious from those what is causing the distorted current waveform.

because you did not show which harmonic is in resonance.

The waveforms show exactly what is happening.
If you want to more of it than what I have comprehensively provided, that's fine too.
As far as I'm concerned, it is what it is. EOS.

 

[gar]

111110-0757 EST

T.M.Haja Sahib :

From the perspective of the homeowner when the power factor correction capacitor is located at the main panel there is no energy conservation for the homeowner. Not one of the following show power consumption.

Go to these various sites:
http://www.electricsaver1200.com/faqs.html
http://theofficialkvarstore.com/residential-kvar-energy-saving-devices/ watch the video
...... then it locks up my Internet Explorer
http://www.apelectric.com/POWER-SAVE-1200-p/jdwps1200.htm watch video

This is fraudulent selling any way you look at the presentations.

.

 

[Besoeker]

http://theofficialkvarstore.com/residential-kvar-energy-saving-devices/ watch the video
...... then it locks up my Internet Explorer

Well, I got it to work - the video that is, not the magic energy saver.
Tests were on an unloaded refrigerator motor. It took 5.3A without the PFC unit in place and 1.6A.
The presenters comment?
"That is 70% less power." His exact words.
I'm sure all here know that's just plain wrong. Dishonest even.
I wonder what The Advertising Standards Agency here would make of that.

The ASA is the UK's independent regulator of advertising across all media, including
marketing on websites. We work to ensure ads are legal, decent, honest and truthful by applying the Advertising Codes.

This is fraudulent selling any way you look at the presentations.

Completely agree.

 

[kwired]

Well, I got it to work - the video that is, not the magic energy saver.
Tests were on an unloaded refrigerator motor. It took 5.3A without the PFC unit in place and 1.6A.
The presenters comment?
"That is 70% less power." His exact words.
I'm sure all here know that's just plain wrong. Dishonest even.
I wonder what The Advertising Standards Agency here would make of that.




Completely agree.

All the consumer will really care about is how much less is registered on the watthour meter which in turn means how much less will my energy bill be, so that is what the test should have used in the first place.

 

[mivey]

I don't see any way in which such comments can be construed as friendly.
If you see it otherwise, that's fine.

They certainly don't read as friendly.

Sahib, if you did not mean it that way then perhaps you would do well to have a friend of yours reverse-translate the way the tone reads in English. It just does not read friendly. All we can see is what we read, and that may or may not be your true intent.

Not that I have anything against being blunt at times, but just call it for what it is.

I gave waveforms with and without the capacitor connected. I should have thought it abundantly obvious from those what is causing the distorted current waveform.


The waveforms show exactly what is happening.
If you want to more of it than what I have comprehensively provided, that's fine too.
As far as I'm concerned, it is what it is. EOS.

I would like for Sahib to present some information to clarify his point: a sketch, scribble, ... something.

 

[T.M.Haja Sahib]

.


Yes. The point is that MVAr for PFC in the context of a residence is an inappropriate unit.

But the formula is applicable in the case of residence.

I gave waveforms with and without the capacitor connected. I should have thought it abundantly obvious from those what is causing the distorted current waveform.

The voltage wave form you gave is prior to the connection of capacitor.(It looks like as if an industrial arc furnace is adjacent to the residence).I do not find the resultant voltage waveform after the connection of the capacitor.

The waveforms show exactly what is happening.
If you want to more of it than what I have comprehensively provided, that's fine too.
As far as I'm concerned, it is what it is. EOS.

I would like to say your excellent study is still incomplete,because you hesitate to apply that formula to find out whether there is any resonance of the capacitor with the power supply.If you do not want to do,please give the size of the capacitor and fault level,I will do.Also state what the current the capacitor is taking using true RMS meter and voltage across the capacitor.

 

[T.M.Haja Sahib]

"Again,you seem to have no idea of why harmonic analysis was required"
"It appears you have misconceptions"
don't actually come across as very friendly.
Indeed they cast aspersions on my intellectual capacity and my capability as an electrical engineer.
I don't see any way in which such comments can be construed as friendly.
If you see it otherwise, that's fine.

I never expected it would hurt you,because my sentences were indefinite:I did not say '' you have misconceptions", "Again,you have no idea of why harmonic analysis was required".
What is more,even experts sometimes do have misconceptions in their own chosen field.

 

[iwire]

The improved voltage profile at the motor due to connection of suitable capacitor across the motor can enhance the working life of the pump motor.The saving possible due to this should also be taken into account for calculating the payback period.

That is what I call grasping at straws.

This idiom refers to a drowning man grabbing any floating object, even a straw, to save himself. It was first used by Thomas More in Dialogue of Comfort Against Tribulation (1534).

 

[Besoeker]

All the consumer will really care about is how much less is registered on the watthour meter which in turn means how much less will my energy bill be, so that is what the test should have used in the first place.

My tests for a similar set up did just that. And found no energy reduction.
Snake oil is a term that has been used here a few times. Singularly appropriate in my view.

 

[Besoeker]

The voltage wave form you gave is prior to the connection of capacitor.(It looks like as if an industrial arc furnace is adjacent to the residence).{/quote]
Not at all. Residential area. The distortion is actually less than I have seen elsewhere. I did explain this a while back.

I do not find the resultant voltage waveform after the connection of the capacitor.

See post#22.
And I directed you to that in post#29.

I would like to say your excellent study is still incomplete,

Not really considering that I got it as a request to investigate possible energy savings, reported, and got paid - about two and a half years ago.
Complete, done, and dusted.

because you hesitate to apply that formula to find out whether there is any resonance of the capacitor with the power supply.If you do not want to do,please give the size of the capacitor and fault level,I will do.Also state what the current the capacitor is taking using true RMS meter and voltage across the capacitor.

Ummm....

I wonder how many residential users actually know their fault level?

The waveforms I recorded are in numerical format. I can and did download that into a spreadsheet to display. Nice.
More importantly, I can use the numbers to perform calculations of instantaneous power, mean power, I_rms current, harmonics etc.
For the purposes of the study, I wasn't required to do so. No harmonic analysis was required despite your assertion to the contrary in post #28.

Back to resonance.
Any LC circuit will have a resonant frequency.
ωL = 1/(ωC) determines that frequency.
In order to close out your point on this, I did some further calculations.
I don't actually know the rating of our local 11kV/400V transformer but, having seen it physically (over the fence in a locked compound) I can make a reasonable guess. I can then assume an impedance of around 5% and calculate Z. That I can resolve into typical R and X_L components and calculate the inductance. I worked on the basis of 1500 kVA.
The resonant frequency with the capacitor worked out to be about 6.7 kHz - 19uH, 30uF.

Now, look at one cycle of the current:

The major components are power frequency related.
There are also higher frequency components. Take the period between 4ms and 6ms.
You can count maybe 13 or 14 cycles over that 2ms period.
So somewhere between 6.5 kHz and 7.0 kHz.
On that basis, the calculated 6.7 kHz seems a reasonable shot at it.
But why bother with the calculations when you have real time data?

 

[jumper]

I wonder how many residential users actually know their fault level?

Not me or anyone I know. I think the US has a limitation for residential 120/240 200 amps or less, which is really common here.

 

[Besoeker]

Not me or anyone I know. I think the US has a limitation for residential 120/240 200 amps or less, which is really common here.

Yes, but the fault level is going to be some multiple of that, most likely determined by the rating of your local transformer.

 

[jumper]

Yes, but the fault level is going to be some multiple of that, most likely determined by the rating of your local transformer.

I think I was referring to that. You are talking about the available fault current and the AIC ratings for equipment,right?

 

[jumper]

Yes, but the fault level is going to be some multiple of that, most likely determined by the rating of your local transformer.

I think I was referring to that. You are talking about the available fault current and the AIC ratings for equipment,right?

This what I was trying to say. This pretty typical for the US.

180.3 On initial services and reconnection after alterations to existing services, the Company will limit
the available fault current on single family detached homes (including mobile homes not in mobile home
parks) to 10,000 symmetrical amperes. This is provided the service size does not exceed 200 amperes.
For all other Customers, both on initial connection and reconnection of an existing service after
alterations, the Company will only notify the Customer of the available fault current.

http://www.dom.com/dominion-virginia-power/customer-service/for-businesses/pdf/bluebook.pdf

 

[Besoeker]

This what I was trying to say. This pretty typical for the US.

180.3 On initial services and reconnection after alterations to existing services, the Company will limit
the available fault current on single family detached homes (including mobile homes not in mobile home
parks) to 10,000 symmetrical amperes. This is provided the service size does not exceed 200 amperes.
For all other Customers, both on initial connection and reconnection of an existing service after
alterations, the Company will only notify the Customer of the available fault current.

http://www.dom.com/dominion-virginia-power/customer-service/for-businesses/pdf/bluebook.pdf

Yes. The fault current.