Jensen Genny

[tajim]

I finally managed to collect all the electrical parts, and began building the assembly. Below is the layout. Since I had a good piece of heatsink, I decided to use it for the lay out as well.

I decided to go with a 24 volt system based on the cut in rpm from the open voltage test I preformed earlier.

I connected two deep cycle batteries together to act as the load.

At 190 RPM's I didn't see any amps on the meter. On the DC side of the rectifier, it was about 23 volts.

When I went up to 260 RPM's, things began to happen. The thing is, I had 21.1 volts on the AC side and 27.2 on the DC side? Of course on the AC side it was across two phases that I was doing the checking. I thought you would loose some voltage when you rectified AC to DC. I don't know if being in a star versus a delta has anything to do with it either. It is wired in star.

I also based the watts on the DC side. I had the amp meter on that side.

I also grabbed the mount to see how much force was against the stop. I had a difficult time at the low speed keeping it off the stop. Tremendous torque! at the higher rpm almost impossible to hold by hand!

Any way I also took thermal readings of the stator as well.

Started with lowest RPM and then progressed to higher until I got nervous and smelled fiberglass cooking.

Here are the test parameters. I ran each rpm for 5 minutes to stabilize the temp reading. I checked different places on the stator but decided to use one specific coil to take the temp reading.

190. RPM-no amps, no load
     
260. RPM-(AC volts 21.1)( DC volts 27.2)( Amps 5)( Watts 136) Temp on stator 123.2 F.
     
320. RPM-(AC volts 22.7)( DC volts 29.1)( Amps 9)( Watts 262) Temp on stator 134.6 F.
     
440. RPM-(AC volts 25.4)( DC volts 32.0)( Amps 19)( Watts 609) Temp on stator 212.3 F.
     
540. RPM-(AC volts 26.4)( DC volts 33.2)( Amps 25)( Watts 830) Temp on stator 235.0 F.
     
     

It looks like it is preforming pretty good. It looks like a rpm power range between 200-450 rpm. I guess when it is up, I can adjust the furl by the amp reading now that I know what is too hot ( about 20 amps at 24 volts.)

I also checked the temperature on the magnets. I'm not sure how much temp. they can take.

I got finished with the test and recorded a reading of 165 degrees F on the magnets.

I am also thinking about the size of the blades. I Should try to find a size that matches the genny.

Now that I have an idea how much power it will put out, I can move on to the mount and finish the rest of the project.

That's all for now.

[Titantornado]

You will always get a higher DC voltage through the rectifiers. Typically, you multiply AC volts by 1.4 for DC and subtract voltage drop across the rectifier. (typ 1.4v)  Your  figures are right on.

One thing I see with your temperature readings is, the generater is not receiving the air cooling it would be receiving up on the tower.  

Nice setup you got there, and what a nice heatsink!

[electrondady1]

this is the first time i've seen temperature readings for a stator

i'm surprised how high they are .

at 440 rpm you can boil eggs on your stator!

 if these temperatures are typical i'm surprised. the stators hold up as well as they do.

i understand now why magnets let go if the resin holing them in place is i65 deg.

[Flux]

Well done, that looks a perfect match for a prop with tsr 7 and 8ft diameter.

With wind cooling you will be ok for 1kw peaks, 5min sustained peak is rare with wind power.

Nice work.

Flux

[Flux]

Those temperatures are modest compared with what most people are pushing things to.

The wire is good for 400 F the limiting factor is the resin, it was never intended for this duty and there are no true figures. Polyester potting varnish is rated at class F, normal fibreglass resins may not be the same material but they seem to stand class F temperature intermittently for a long time. Vinyl ester is better and should manage true class F. Normal epoxies are soft at 212F and are not as good for stators ( better adhesive for magnet rotors). Special motor potting epoxies ( commercial VPI resin) are class H and retain reasonable strength but will be expensive and not generally available unless you can dip some from the tank of a manufacturers VPI plant.

Running wire at class H in motors is common, but the slots hold the wire and the varnish only has to prevent vibration and not provide physical support.

This temperature issue is the main factor that makes some form of mppt attractive, much more so than the better prop matching that raises speed and noise ( stalled machines are peaceful and tame and pleasant to live with).

Flux

[Titantornado]

"I also checked the temperature on the magnets. I'm not sure how much temp. they can take.

I got finished with the test and recorded a reading of 165 degrees F on the magnets."

 From what I can find, maximum operating temperature of standard neos is 176 F, so you were getting right up there.