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Forum Index : Windmills : CAPACITERS and why they Work

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FandPwithPVC
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Joined: 09/09/2006
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Posts: 64

Posted: 10:34am 23 Dec 2007

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Hi All Much debate has been had about why they wont work and trying to undermine what we have achieved with the 80 SP in Star. Before your mouse clicks there is some basic information. Lots of people have done rewires and although capable of some good outputs at speed 290 RPM and not 260 RPM is required before anything starts to happen. This is too high for good blade performance and there was a need to lower this. We have destroyed many blades by over revving with insufficient load. The capaciters in question will.
1. Lower the start up speed required to 200 RPM
2. Rapidly rise to 26 Volts
3. More than double output Amps
4. Cost very little and be safe to use
5. Be more suited to slower blades
6. Not effect speed or torque above 500 RPM

FandPwithPVC
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Joined: 09/09/2006
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Posts: 64

Posted: 11:04am 23 Dec 2007

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Page 2 Capaciters and why they work .
In seeking caps I made a new aquaintance. He owns a mid sized Electric Motor Rewind Company. He was some what scepticle and talked in terms well over us. Anyhow he must have thought about it and visited our "Test Facility"Looking at the F and P he stated that from a generator point of view they would not be very good. Looking at our capaciter set up he was fascinated as to how we had arrived at the outputs he was seeing.We explained how we got there with basic stuff and he said we had corrected most of the F and Ps Faults. YES he was able to measure some very minor input requirements which we are/were aware off . It is said you do not get anything for nothing What if all our cars had its hand brakes on and we didn,t see or recognize there poor performance.We have removed this brake. Regards Dennis L

FandPwithPVC
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Joined: 09/09/2006
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Posts: 64

Posted: 11:30am 23 Dec 2007

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HI ALL
In Reply to Adelaide on the OUTPUT PAGE . We have cascaded all over the place with connecting caps up in various wiring ways. We settled on 300uF after going up and down many times and at varying speeds. Going up does not increase output and only adds slightly more load to the 240 Volt drive motor. Going down results in a decline in output. Given you are in Adelaide I could lend you a set of Caps.

THIS IS NOW THE NEW TECHNICAL PAGE FOR CAPS. We have done HZ testing and with caps the HZ drops of a little but no big changes. Regards Dennis L

KiwiJohn
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Joined: 01/12/2005
Location: New Zealand
Posts: 691

Posted: 06:41pm 23 Dec 2007

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[quote]We have done HZ testing and with caps the HZ drops of a little but no big changes.[/quote]

You have found adding capacitance reduces the Hertz? How are you measuring this?

Thanks.

FandPwithPVC
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Joined: 09/09/2006
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Posts: 64

Posted: 09:36pm 23 Dec 2007

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Hi All
In reply to Kiwi John and reducing Hertz. We have a Jaycar Clamp Meter to measure this. The Hertz or Frequency is not much affected by caps and at this stage is not important.
When looking at a crow (Not ours) it shows a very stepped waveform. Adding caps smooths this out to a more traditional pattern .

All for now Dennis L

adelaide
Regular Member

Joined: 24/03/2006
Location: Australia
Posts: 46

Posted: 10:04pm 23 Dec 2007

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cool thanks for offer of caps only if u comming past . i did try a few and posted a result on welding thred looks like my crude test , 3 kw out a 100 p at hi rpm around 1500 with some caps but only had 100 to 200 uf and testing 1 coiland x bye 42 after . but defonaly helped it put out more watts at the same rpm . i suspect from another better test(done on hear by some 1 els ) it may be slightly less efishent with watt in vs watt out but the fact u can run bigger props and that more than makes up for it . would be good if u could use clamp meter on drive motor as a extra mesherments so peple can work out efishency and find sweet spot exactly eg 3 amps 240 v ac in 300 rpm no caps 1 amp output 24v and 3.3 amps 240 v in 300 rpm 300uf is 4 amps 24 v out . a few points like that over rev range and load befor output would make intresting factal results which even the paper work therioy boys would like . good work looking farwad to seeing re results

help to make progres or radio and vitamin b

KiwiJohn
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Joined: 01/12/2005
Location: New Zealand
Posts: 691

Posted: 02:48am 24 Dec 2007

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Dennis, I think we can be confident that the frequency (i.e the Hertz) will not change and will always be the same multiple of the RPM.

No doubt your clamp meter is accurate on a pure sine wave but perhaps when the shape of the wave becomes more complex the meter has difficulty getting an exact reading.

Electronic theory says a sine wave is a single frequency but anything else is made up of a combination of frequencies (and a square wave is made up of all frequencies!).

As you observeD on the CRO capacitors will smooth wave form and more of the energy will be at the main frequency, which is good.

All your observations are in line with my modest understanding of the theory and I can only add "keep up the good work!"

domwild
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Joined: 16/12/2005
Location: Australia
Posts: 873

Posted: 03:14am 24 Dec 2007

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Dennis,

Your are correct, caps will increase output as per that scientific paper by Dr Tom Chalko. His cap figure uses a hydro example with higher RPMs, so it is unfair to claim his cap figure of only a few uF is incorrect.

This is not the first time I have seen caps at the AC side. Flux also agrees on the benefits of caps.

What members of this board objected to is stating not to bother with MPPT as caps will give you more power anyway. MPPT is a hard nut to crack otherwise there would be lots of cheap commercial units around. MPPT will also give you a better matching of generated power to load.

And have a Merry Christmas, all you F&P enthusiasts!

Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill

KiwiJohn
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Joined: 01/12/2005
Location: New Zealand
Posts: 691

Posted: 04:41am 24 Dec 2007

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Ummm, MPPT is not a substitute for capacitors or vice versa, IMHO of course!

FandPwithPVC
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Joined: 09/09/2006
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Posts: 64

Posted: 10:00am 24 Dec 2007

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Hi All John You are correct that the frequency will always be the same multiple of the RPM .Bruce Nielson who is the more electrical gifted of our team states.
1. The F and P before caps have small Current Resistance losses in the coils
2. Also in the coils there is a large Henri Induction
loss and this is what we have all but eliminated.
3. The condensers are opposite to the Henri and at a certain frequency they cancel one another out. This is why there is very little if any increase in load.
4 With Caps the current is in phase with the voltage and does not overlap.
5. Our condensers do not affect the iron laminations or the cogging. All for now Dennis L

herbnz

Senior Member

Joined: 18/02/2007
Location: New Zealand
Posts: 258

Posted: 06:12pm 25 Dec 2007

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Hi Dennis You are correct in referances to current lagging capacitors correct this. All very common but confusing concept why we use power factor correction in electric motors.
As matter of interest the 7.3 amps drawn by you drive motor of load is largerly reactive lagging no power in it as you put load on it comes into phase little increase current but huge incrrease input power.
Try one of you capacitors connected across phase neutral on you drive motor say 40 mfd and then measure supply current .
What I find with your testing is the results are meaningless to me as they do not relate to input power.
I know and understand from my training and experiance what is going on with caps and they do have a place , I have used them to adjust output charcteristics of hydro's I build.
Measuring input power is only a small step from what you are doing now.
My mention of getting more complete with our testing has meet with negative response much as you feel here IMAO .
I will however bit the bullet and start a topic on a test set up.
Herb

Chipboy
Newbie

Joined: 13/12/2006
Location: Australia
Posts: 16

Posted: 12:00am 27 Dec 2007

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ost likely the capacitors are matching the reactive impedance of the coils in the generator and by their own capacitive reactance cancelling them out to make the whole thing resistive (current in phase with voltage).

This is power factor correction.

X = Reactance
L = inductance
C = Capaitance

X of inductor = 2pifL
X of capacitor = 1/(2pifC)

Current lags volatge in an inductive load.
Current leads Volatge with a capactive load.

Increased power is being seen at the DC point since power is a product of instantaneous voltage and intantaneous current. If they are not in phase the power drops. This is exactly why the power company likes you you to have resistive loads, since if you dont they send a lot of power to you, your loads only use what they need though and the rest is required only to be wasted by your load changing the phase relationship between voltage and current (eg fridge with inductive compressor load).

You are not really seeing more volts, the caps are charging to the peak voltasge of the sine wave output but they will not delover more power since by the laws of themrodynamics, energy is neither created or destroyed cut changed into different forms. Your multimeter is reading RMS voltage (root mean square)

All theory of course and some experience and I have been wrong before!
Matt
BE ElecEdited by Chipboy 2007-12-28

Wind wannabe

KiwiJohn
Guru

Joined: 01/12/2005
Location: New Zealand
Posts: 691

Posted: 01:35am 27 Dec 2007

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There would seem to be some scope for adjusting the value of added capacitance according to frequency (i.e. RPM)

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