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thanks ghurd | 13 comments (13 topical, 0 editorial)

Re: thanks ghurd (3.00 / 0) (#1)
by ghurd on Wed Jun 4th, 2008 at 01:30:55 PM MST
(User Info)

The series parallel thing. I think that's a mistake if you mean the heaters are the same, but I don't know.

IE: it would only be 4 steps.
If each heater is 10 ohms, the resistance would go 50, 8, 4.3, 2.86, then 2 ohms.
Pretty large jumps?
The 6 heaters and 2 each of star and delta thing would have the steps a bit more reasonable?

Switching 6 heaters between 4 configurations isn't a problem. Just a few relays and a logic circuit.

Probably need a cut-off circuit so there is no load until at least 6MPH, and (if it was me) more like 8MPH.

The switching speed (RPM?) would need some play. Unloaded at 6MPH may be faster than loaded at 6MPH. If you know what I mean. Sorry if thats mostly pertenint to HAWTs, but my VAWTs never work much.

If the PMA had 12 wires out, then it would allow 4 voltages.
If one "coil" made 10V, the choices would be 10V, 17V, 20V, and 34V.
The available power would be the same, but the available power, voltage and resistance could be tweaked to match.

Might even be helpful if sometimes the sine wave was only half wave rectified.
That would bring the effective voltage coult up to 8.
For 30 combinations. Yea, I think it's 30 instead of 32. Didn't think it through. Kind of in a rush right now.

The PWM Stamp or Picaxe thing could fix some of the issues. Gizmo Glenn's site might have something related.
Seems like "low frequency", 500Hz to 5KHz?, could fix most of the issues, if someone (not me) understood those chips. And wind and TSR and loads and power available and PMA efficiency.

Myself?
I'll be happy with the 12V 10W my kind of fly-able thing dumps,
Smile,
Pay my gas bill,
And be happy the insulation is good.

With luck, someone posted something better that this while I was 1 fingered typing.
G-

Re: thanks ghurd (3.00 / 0) (#2)
by electrondady1 on Wed Jun 4th, 2008 at 02:52:19 PM MST
(User Info)

yikes!!
,sorry i asked.
thats mostly over my head.
obviously ,i will need another method.

[ Parent ]

Re: thanks ghurd (3.00 / 0) (#3)
by electrondady1 on Thu Jun 5th, 2008 at 07:21:04 AM MST
(User Info)

i wonder if it would be simpler and within my understanding
to have a heater hardwired to the mill
and then use some sort of thermostat on the first heater
to close a ciruit on a second heater.

the thermostat would need to work in reverse so to speak
closing a switch when a predetermined temperature is reached,

when the second heater reaches it operating temperature another unit
could be switched in.

[ Parent ]

Re: thanks ghurd (3.00 / 0) (#4)
by ghurd on Thu Jun 5th, 2008 at 09:10:01 AM MST
(User Info)

Too slow reacting.

Ain't this fun?

[ Parent ]

Re: thanks ghurd (3.00 / 0) (#6)
by vawtman (vawtman(at)charter(dot)net) on Thu Jun 5th, 2008 at 05:49:41 PM MST
(User Info)

Hi Edaddy,
Why not have one element matched to the predicted full load of the turbine?

The resistance of the element is there but would gradually increase until it's rating.

I don't think starting would be an issue.

Am i wrong here?

[ Parent ]

Re: thanks ghurd (3.00 / 0) (#7)
by ghurd on Fri Jun 6th, 2008 at 12:04:24 PM MST
(User Info)

Very wrong.

Say it is a 12V 1000W machine.
Full load is 14.5V and 69A. That needs a resistance of only 0.21 ohms. Close enough to a dead short to act like a shorted windmill, in my experience with small stuff.

Direct windill heating seems to be a nightmare.

Zubbly did it with giant caps, and documented it. I think someone else (or 2) did too, but I can't recall who.

Maybe Hugh's Nirvana did heating(?), but it had circuits that were RPM and Hz driven, IIRC.

MtnMike must have low TSR blades?
I can't see it working well with high speed lift blades. Might be OK for a water pumper... OR a VAWT!

I am not an expert... I simply stated something about parallel resistance.
A 'smack in the face with the obvious facts' often causes the clarity needed to see deeper into the 'big' problem.
Sometimes my face hurts for weeks on end due to repeated smacking. :-)
G-

[ Parent ]

Re: thanks ghurd (3.00 / 0) (#8)
by vawtman (vawtman(at)charter(dot)net) on Fri Jun 6th, 2008 at 03:39:09 PM MST
(User Info)

Hi Ghurd
Back in the 5hp cogging conversion days.I had a 2100w hand dryer element hooked up between 2 of the 3phases and there was no difference at startup with the element there or not.It got pretty warm but maybe half it's rating.

Maybe because it took a stiff breeze to break cog.

That setup and gearing went to my pile after one afternoon. :v)

Mark

[ Parent ]

Re: thanks ghurd (3.00 / 0) (#9)
by elvin1949 (elvin1949@yahoo.com) on Sat Jun 7th, 2008 at 12:40:13 AM MST
(User Info)

G
DaveB did it direct hookup. But i think he used High Volts.
later
Elvin

[ Parent ]

thanks ghurd | 13 comments (13 topical, 0 editorial)

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