volts, amps, ohms watts etc...

[dom]

Hi guys

I need some help about electricity, I thing my grandma knows more than me about it 

We have built a machine with 18 coils-24 mags (dual rotor)
It's a vawt
The coils from 22 awg wire & mags 2X1X0,5 neos

We connected the coils for 3 phase star the way you see (is it ok?)
(Link removed until someone smarter than me looks at it)

Now, we found
On 60 rpm 58 volts between start & end of one phase
On 120 rpm 80 volts
On 150 rpm  100 volts

On 60 rpm 80 volts between two phases
On 120 rpm 150 volts
On 150 rpm  180 volts

And

On 60 rpm 55 volts between a phase and neutral
On 120 rpm 80 volts
On 130 rpm  150 volts

We try to measure the amps but we cant.
We suppose we can find the amps from this : V=I*R, so I=V/R
From the AWG table for copper wire we see that the resistance (R) for the 22 awg wire is 53 ohms/km.
Now,
For each coil we have about 38 m copper, means for 6 coils (one phase) we have
38*6=228m copper wire, means about 450m for 12 coils (when we connect and measure between 2 phases.
I suppose it gives about 24 ohms, so the amps must be 80/24=3,3 (60 rpm-80volts)
And 150/24=6,25 (120 rpm-150volts).
But we don't have so many amps really.
May be simply (or silly in fact) calculations.
Is there another way to find the amps?
What is the power we can get from on these rpms-volts? (60-80, 120-150, 150-180).

Gently please, we are mechanics not electricians 
Thanx

[ghurd]

The link hyjacked my IE, refused to let me close it, started "Your computer is at risk" crap.

What is the plan for the PMA?
If it is battery charging, then it needs connected to a battery.

G-

[joestue]

On 60 rpm 55 volts between a phase and neutral
On 120 rpm 80 volts
On 130 rpm  150 volts

i think you need to get a better volt meter.

38*6=228m copper wire, means about 450m for 12 coils (when we connect and measure between 2 phases.
I suppose it gives about 24 ohms, so the amps must be 80/24=3,3 (60 rpm-80volts)
And 150/24=6,25 (120 rpm-150volts).

the amps here would be short circuit amps, and you would have to supply 246 and 937 watts mechanical input to your alternator to get those readings.  (1/3rd and about 1.3 hp)
in this reguard, (assuming that the magnets don't heat up due to eddy current) the alternator is a 100% efficient heat generator, providing no usefull electrical power.

if you are charging a battery or whatever, you have to subtract those volts from your alternator volts, then divide by the impedance of the alternator.

[dom]

sorry ghurd, i just posted a pic via imageshack as allways, u can see it as attached file its the same.

no battery, just testing.

........

joestue, thanx for the advice the meter is ok and tested, what's wrong with the readings?

we get these readings turning the rotor ourselves, it turns free and easy.
the mags dont heat at all.
so, as u say, we are about to make a nice machine to bake some toasts or steaks , better than nothing.

anything about connections & calculations?

[Flux]

Yes I agree your voltage figures ( or probably more likely your speed figures) are suspect.

The volts should be directly proportional to speed so your 120 rpm voltage should be double your 60 rpm figure.

I assume you are trying to charge a battery, in which case you need to rectify the ac before attempting to measure current.

You will need to actually measure the current with an ammeter with the thing charging a battery. What you were trying to calculate is short circuit current in the alternator and for some crazy reason a lot of people go to the trouble of measuring this although it is of no practical use.

For your voltage figures I assume you are aiming to charge a 48v battery but you need to give more information to be able to help.

How you are planning to load this thing makes all the difference to how you measure or calculate current and power. At best your resistance is high so you will not get very large currents and you will certainly get far less useful current than your predicted short circuit current.

Flux

[ghurd]

Volts per RPM should be a fixed value, when measuring it in the same configuration.

The reading for 120RPM should be twice that of 60RPM.
The reading for 150RPM should be 2.5X more than 60RPM.

"between start & end of one phase" should be the same as "between a phase and neutral".

Even my cheap meters usually read it pretty well.
I have to guess the RPMs must be inaccurate.

Connect all the phases and all the rectifiers, and measure the DC voltage.  That's what I do.  More stable readings (usually).
G-

[Flux]

Having just seen your reply I feel certain that it is your speed measurements that is in error. Your voltmeter is probably good enough. You only need one point reading if you get it right, counting speed by hand is easier at 120 rpm so try to get a decent consistent voltage reading there.

Flux

[dom]

flux & ghurd thank u so much.

you are right. we made the turning and measurements again and carefully and we have really 60-78 & 120-152.

then, just "playing" and testing, we connected some lamps (between 2 phases and between a phase and N) to see what happens.
so a lamp 110v-40w lights up normally and another one 220v-60w does the same.
Probably this means nothing but we suppose that the amps are about 0,3 to 0,35 (W=V*I), we have no ammeter.
But, as u say, by this we are doing a short circuit calculation.

This is how we begin flux.
We fixed some blades, put them including the rotor on the roof for some days and we count about 160rpms with some good winds (9 to 10m/s).
We suppose that the thing full loaded (coils etc) will be turning on 120-140 rpms on these winds.
That's why we are making measurements depenting on these rpms.
Maybe is not the correct method but we have to start from something.

[Flux]

That's encouraging, if your 60W lamp lights up well then you must be producing at least 60W. If your voltage is that high you won't need much current to produce useful power. If you are intending to charge batteries you probably have too many volts but I don't know your aims.

Flux

[wooferhound]

22 gage wire is only good for 2 or 3 amps before heating becomes a problem

[dom]

Not so encouraging flux. To get 60 watts we must catch 220v, means we turn it about 300 rpms, al little hard.
We were hoping to get those watts with 130-150 rpms. So we need more current, means less resistance-thicker wire i guess.
But then we'll have less volts, seems comfused.
We are able to change easily the coils woofehound so we'll try with different coils, 20gage lets say or 18 to have less R but then we'll have less turns (per coil), less copper...
Anyway.
Is the gap important? we can easily change it too (in-de-crease it).
We are not very interested to charge any batteries. We were planning to put 2 of those machines on a small country house and let them work adding some inverters to get power, the place has allways good winds.

[rossw]

Not so encouraging flux. To get 60 watts we must catch 220v, means we turn it about 300 rpms, al little hard.
We were hoping to get those watts with 130-150 rpms. So we need more current, means less resistance-thicker wire i guess.
But then we'll have less volts, seems comfused.

In order to get the same volts at lower RPM you need MORE turns and/or MORE magnetic flux.
Thicker wire will help you pass more current... but as you already know, thicker wire means less turns in the same physical space.
You have a problem! Thicker wire and much more magnetic flux?

We are able to change easily the coils woofehound so we'll try with different coils, 20gage lets say or 18 to have less R but then we'll have less turns (per coil), less copper...
Anyway.
Is the gap important? we can easily change it too (in-de-crease it).

Smaller gap usually means more magnetic flux, but may cause you problems with startup.

We are not very interested to charge any batteries. We were planning to put 2 of those machines on a small country house and let them work adding some inverters to get power, the place has allways good winds.

This one concerns me. If your wind varies at all, your output will vary in both volts and frequency. As your (electrical) load changes, so too will the load on your turbines. That could easily see you put your blades in stall, or conversely in a state of insufficient load and overspeed.

A complex control system using dump-loads etc to keep the turbines loaded adequately depending on available power and your power demands at the time might help, but it won't help if your demand is more than your ability to generate.

Batteries are a great "equaliser" - you can provide additional power for starting motors etc, and "soak up" extra power as it's available. I guess it could be done as you suggest, but I think it will make an overcomplex system with far too many oportunities to fail.

[Flux]

The only option you have is to close the air gap. There is little else you can do to get more power at lower speed without adding more magnets and coils.

For direct lighting on 3 phase you should load all the phases equally. Either from line to line terminals with 3 lamps or with 3 lamps connected from neutral to each line, depending on the lamp voltage.

I agree with RossW that it is unlikely that you will be able to run direct loads from an unregulated turbine. You would need the equivalent of a hydro shunt controller to maintain constant voltage and of course this would only work if the input power was always in excess of the load.There are Few sites that have this consistent source of wind and there would always be day when you had nothing.

Flux

[dom]

Ok, now we talk better.

What we have:
1.   good winds almost every day in the specific area (see attached file, we are in the dark blue area, 9 to 10m/s)
2.   200 rpm after some improvements (blades)
3.   a machine giving at least 200-220v
According to what i read, its better and easier to charge batteries rather than look for direct power. So,
What we can do:
1.   change the coils wire gage (to 20 or 18?)
2.   smaller gap
What we can't do:
1.   add more magnets
2.   add more coils

Is that all?

[dom]

I guess that's all.
We'll try those changes-improvements and see.
Thanx evrybody.

Jim

[dom]

Hi again.
As i said, i dont no much about electricity.
I rectified the thing (star) and i read 95-100v at 60 rpm on voltmeter (DC).

1. When i connect a test lamp (110v-25w or 110v-40w) the lamp lights pretty good but its a little hard to turn the machine and while turning i feel vibrations and a little noise. Why?
2. I f i reconnect one phase (random pair of coils) the thing turns much easier and the lamp lights too.

And something else that makes me worry. There is an aluminium disk (or ring) wich i use to hold another  disk (plastic) holding the coils. I read some volts there, about 15 to 20.  The aluminum plate is far enough from the rotor and the stator, about 4 inches. Where does it come from?

What did i do wrong?

thanks
Jim

[joestue]

The voltage on the aluminum disk is leakage current.

Not sure what you mean in point 2, 'reconnect one phase'.

the vibration you feel is called torque ripple, it is essentially unavoidable.