Delco PMA testing with caps.

[Jerry]

I did some bench testing with and without caps.  The test alternator is a stock factory wound 24 volt Delco stator using a NEO magnet rotor from an old Hornet alternator. The phases are seperated. A fullwave bridge is conected to each phase. The DC outputs of the bridges are wired in sires. One test was done with caps on the dc output of each bridge. The same tests were done without the caps. The prime driver motors power consumption was calculated at alternator outputs of 1, 2.5, 5, 7.5 and 10 amps. I was surprized to see at 1 amp the cap version required only 45.5 watts of driver power but the uncaped version requiered 73.5 watts. After that point things began to change quite abit.  If you can see my notes in the pictures you'll see what I'm talking about. By 7.5 amps the none cap version is the clear winner. I've put the machine back up on the tower. I've also incorperated a switch to at the rectifiers in the shop to switch between these 2 scheems while the unit is flying. Unfortunetly there been no usable wind since puting the genny back up on the tower. Just waighting now. Hope these pictures are veiwable? First with caps. Now without caps

Jerry

[Jerry]

Just a couple notes. The watts are shown in the drive motor v box on the slanted line. This is drive motor watts consumption. In the none cap rpm colum the 7.98 rpm is actuly 798 rpm.

I'm using a 56" diameter blade on this genny.

Jerry

[electrondady1]

it's very interesting to me Jerry as i build drag verticals and  always looking to improve output
i have been reading your other post about running 3 phase interdependently and rectifying ,condensing and running in series.

it looks as though the caps help out a great deal at low power levels/rpm
but they're holding back the alt at peak power.
is that the way your interpreting the readings?

i'm no electronic guy and barely understand how caps work.
but i wonder if the difficulty may be in running a dc source (one of the phases rectified )
kind of backwards through a rectifier into an alternating current coil.?

[electrondady1]

i wonder if your running six wires down the tower or two?
i wonder if  this (bottle neck) effect would take place with  a resistance load were the volts can float.?

[Jerry]

I think we need Flux to bringe his knoledge to this one. I still have low wind. I did however see a littel out of the genny this morning. The wind came up to about 6 mph and I was seeing .8 amp with the caps turned off. As soon as I engaged the caps the amp gage went to 0. All the other units were still reading 0 amps though. Out of the 3 diferant Delco alternators, this unit has the earlyest cut in. I hope it also has the highest output. Won't know that till the wind comes up.

I know the general feeling here is that the Delco alternator style wind generators are worthless and I tend to agree. However there are a bunch of companies selling these things and many people are being missled and disapointed. I'm just having fun getting much better prefrmance then the comercial stuff and maybe finding away for people to get better power out of  there none preforming machines. I enjoy seeing 5 amps out of my home built Delco alt. wind generator when the Wind Blue right next to it is getting 1/2 (.5) amp. I'm not  sure why the comercial guys arn't doing what I'm doing and trying to improve there machines? There have been improvements since the early days but there all still using the power waisting star conection and crapy blades.
I'll just keep expirimenting and having fun. OK Flux where are you?
Jerry

[bj]

  Jerry--following this one with interest.  Still have 3 GM"s various sizes, windings.  Oh ya and blades.  Always wanted to try
IRC, but never got round tuit.  I kind of miss the Banshee shriek in higher winds.  (wife does not however)

[Jerry]

  Jerry--following this one with interest.  Still have 3 GM"s various sizes, windings.  Oh ya and blades.  Always wanted to try
IRC, but never got round tuit.  I kind of miss the Banshee shriek in higher winds.  (wife does not however)

bj. Help me out here I'm an old guy. What is IRC?  Thanks.

Jerry

[bj]

   Sorry, forgot.  As in Jerry rigged.  Someone a while back suggested Independently Rectified Coils.  My Bad.

[electrondady1]

i am curious, if you rectify phases separately and then wire in series and then use one big cap for the entire circuit.

two years ago i was running a string of leds off a little rectified single phase mill ,
they seemed to be happy until i put a cap on the end of the rectifier and that would blow  the leds out.
i thought it was a change in amperage.

[Jerry]

i am curious, if you rectify phases separately and then wire in series and then use one big cap for the entire circuit.

two years ago i was running a string of leds off a little rectified single phase mill ,
they seemed to be happy until i put a cap on the end of the rectifier and that would blow  the leds out.
i thought it was a change in amperage.

The cap and the battery will have a simular effect on voltage Battery voltage rizes slow, cap voltage rizes when it the only thing connected. Here is a no load situation. The rectified dc coming out coming out of the fullwave bridge recifier will be about the same voltage as the ac volts coming in. This is a no load or nothing connected to the dc output of the bridge. Connect a cap and the voltage goes to about 1.4 times the ac voltage. This is a no load condition. The LEDs basicaly represented a no load condition. Because the caps was connected the voltage went up and the LEDs went pooof.
Jerry

[artv]

Hi Jerry,....I'm confused here .....if I have a cap hooked to the output of the bridge ,...It (the cap) will gradually increase in stored voltage the longer you rotate ..........correct??
If you hook a battery to the cap (paralelled).... will the battery clamp the stored voltage of the cap to its' (the battery's) capacity??
That is to say will the battery lock the cap to the voltage of the battery??
All this is assuming the battery is not up to full charge..........
If I hook a full charged battery to the caps.....they charge to the reading of the battery........as I rotate the genny the volts continue to climb......does that now mean that I am over charging the battery??.........and this is when you should add a load to take up the excess ?.........I just don't want to cook my caps ,or my batteries.....       looking for bigger caps........artv

[Jerry]

Hi Jerry,....I'm confused here .....if I have a cap hooked to the output of the bridge ,...It (the cap) will gradually increase in stored voltage the longer you rotate ..........correct??
If you hook a battery to the cap (paralelled).... will the battery clamp the stored voltage of the cap to its' (the battery's) capacity??
That is to say will the battery lock the cap to the voltage of the battery??
All this is assuming the battery is not up to full charge..........
If I hook a full charged battery to the caps.....they charge to the reading of the battery........as I rotate the genny the volts continue to climb......does that now mean that I am over charging the battery??.........and this is when you should add a load to take up the excess ?.........I just don't want to cook my caps ,or my batteries.....       looking for bigger caps........artv

I used the caps only when I use the sires configuration. The center phase does not have a direct conection to the battery. Having the caps inplaced allows the voltage to clime to a higher point then without the caps. However the battery sets the maximum voltage. It is the vergulator and chife. Voltage accross the caps only will rise uncontroled. Voltage accross the battery is much more controled then accross the caps. The battery some what sets the limmet. However with enough amperage the battery voltage can also climb to a dangerus or damaging point (WA-LA) dump load. When the caps are wire in the same configuation as the battery the battery is in control not the caps.
Jerry

[XeonPony]

think of a cap much like a bucket, you can fill and empty it very fast where as afuacet has a fixed flow. A cap can all so filter out noise, but in this case lets look at the previous function only.

You are correct that a battery will clamp the total rise in voltage tot hat of its own plats, in this case the capacitor will allow very high surge power allowing the cell chemistry to catch up with the load then the cap will rise with the wire v again.  in the wind geny case on the dc rail, it will hold surge currents and feed them back out if one where to use a diod, so it can only send the extra stored power in one way.

Baswicaly a cap is a tank it can hold charge and dump it in a flash, how you determin the best use of this function is up to you.

[ruddycrazy]

G'day Jerry,
                Years ago I got some 400 volt 470uf electro caps then put 2 back to back to make them non polarized and put 3 sets one on each wild AC phase. I was using a 100 series F&P washing machine motor rewired and setup in delta and the increase in amperage was a shock to see. Maybe give this concept a go and see if it will work with your setup. But just remember to use caps with a BIG voltage margin so they don't go pop or BANG on you.

Cheers Bryan

[Flux]

Yes with an iron cored machine with high leakage reactance and salient poles affected by armature reaction, capacitors across the windings will bring a lot of benefit. with that type of alternator it is also possible to put capacitors in series with the windings and neutralise the leakage reactance at one frequency.

What Jerry is doing is connecting single phase rectified windings in series after the rectifiers, so the ripples have different phase relationships. With infinite capacitors the result will be 3 times the peak phase voltage. With smaller capacitors this will be true on no load but it will not be true with significant load.

How this affects things may be as much determined by prop matching as any electrical consideration. it is tricky to form any idea of how relevent the bench tests will be.

I have meant to plot out the two sets of figures and see which looks most likely to be a good shape to match the prop, but other things need dealing with at the moment.

Flux

[Jerry]

G'day Jerry,
                Years ago I got some 400 volt 470uf electro caps then put 2 back to back to make them non polarized and put 3 sets one on each wild AC phase. I was using a 100 series F&P washing machine motor rewired and setup in delta and the increase in amperage was a shock to see. Maybe give this concept a go and see if it will work with your setup. But just remember to use caps with a BIG voltage margin so they don't go pop or BANG on you.

Cheers Bryan

I do have 20 of the 4600 UF/ 400 volt caps. Not sure if 2300 UF would be to high. Or is there no such thing as to high UF in this aplication. I've been using these caps in my OTL guitar amps.
Jerry