Iron core stator part 2

[Hilltopgrange]

Hi Guys it has been a while since I posted on progress with the stators I got from ebay so here is what I have managed to do so far

As a quick reminder  

3 phase 18 coils with 6 per phase overlapping

Coils are wound 2 in hand of 1.2mm dia and occupy a slot area of 9x10mm

Im unable to count the turns yet with the varnish but I would guess at about 40-50 per coil

The outside dia of the stator lams is 285mm (11 1/4in)

The inside dia is 165mm (6 1/2in)

 The depth of the lams is 35mm (1 3/8in)

Coil legs length are about 65mm (2 1/2in)

The lams have 36 slots

I have made up a rotor and fitted 12 neos n50 2 x 1 x 1/2 the mags are only fitted temporary with duct tape just to get some figures. (I will post more detail of the construction etc later)

Maths is not my strong point so please forgive me if I have gone wrong

I bolted the stator to section of H beam and secured it to the bench so that I could drive it with my lathe. The lathe is a bit of an antique so there is no fancy speed control etc but after a bit of fiddling about with pulleys and a long v belt I have managed to drive it 1-1 and change speed with the gearbox and belt. The speed was measured with a digital tacho so should be close but I have also noted the frequency as well.  All tests where without load and the meter was connected between the star(coil ends)  and 1 phase (start) Im not sure if this was the correct way to do it but no doubt someone will put me right!

Results

180. rpm  20hz  11v ac
     
310. rpm  33hz  19v ac
     
890. rpm  96hz   54v ac
     
     

With the meter between 2 phases (starts) the above voltages doubled

My target cut in is for 48v battery charging so I think it will be about 200rpm

I am probably wrong but for what its worth here is how I arrived at 200rpm.

11v * 1.4 = 15.4v *3 = 46.2v / 180rpm = 0.2566v * 200rpm= 51.33v

As I said earlier maths is not my strong point but at least I tried!

I have no idea how to figure out how much power to expect but from reading old posts from Zubbley 140-150w per cubic inch of magnet 145*12=1740w

The resistance of a single phase of 6 coils is 0.3 ohms but I have read posts that say you can't measure the resistance with a normal meter? You need to know the total length off wire per coil to work it out, obviously I cant do that. If I apply ohms law to my known figures I get the following

V/R=I so 56v/0.3 *3= 62.22 amps

V *I = W so 56 * 62.22 = 3484 watts

But that cant be right surely so I will let those that know correct my mistakes on this!

I haven't got a clue how to work out the losses or the efficiency for this and

as for blade size I am guessing about 15-16 ft dia blades but I am probably wrong on that score as well!

  There is a little bit of cogging but its not to bad it would be similar to a future energy PMA and it has skewed lams? So I think it will be ok

I would like to be free from stall on this one as I will have a mechanical brake and a furling cable fitted for shut down.

 I have tried to include as much detail as possible but no doubt I have forgotten something vital so if I have just let me know.

 Any help, advise or comments would be most welcome

As Albert Einstein said "  If we knew what it was we were doing, it would not be called research, would it? "

Many thanks in advance

Russell

(I tried to continue this in the original diary entry but for some reason it didnt show up)

[Flux]

You say that you have the meter between the star point and one phase connection.

Take your second reading as an example.

310 rpm ( 330 from frequency, tacho is more likely to be correct) 19v ac ( phase)

That gives a line voltage of 19 x 1.7 = 32v . Rectified dc will be 32 x 1.4 = 45.2v dc.

Cut in at 48v will be 319 x 48 / 45.2 = 330 rpm  Too fast for 15ft blades.

Power out I haven't a clue, but I think it may not show much reactance limiting at lower powers.

Based on resistance alone at 500 rpm you will have an emf of 72v. Difference over battery is about 24v. With .6 ohm winding resistance you would hope for about 40A. We know from experience that it will be way below this so perhaps 25A so lets say 1200W.

This is more suitable for something 10ft or less. I think you will need speed increase to even have a chance of loading 15ft.

All very crude and approximate and based on very little evidence but perhaps a starting point.

Flux

[Hilltopgrange]

Hi Flux

       Thanks for the reply, I understand this is all very rough my intention is to see if it is worth the effort as a turbine or maybe as a diesel driven gennie. Thanks again for the input.

Russell