anybody running a pm head?

[mobile_bob]

anybody running one of the pm heads?

how are they working out for you? 

did you change over from an st head to the pm head? if so
how do the pm heads compare to st heads in power output for fuel consumed?

anybody?

bob g

[panaceabeachbum]

I am curious also , i have been looking at the one at Utterpower  . I see Ga Gen has a couple also

[bschwartz]

I have an st-5 from Ga Gen (Tom Osborne).  I am about to buy a PM gen head from him in the next few days.  Although I don't have any plans to implement any fuel use tests, or even carefully detailed power output, I will gladly give my general novice impressions of both after I receive it and put it through a few hours of use.  Looks like I may be the first on this board to get one from him. 

Looking forward to the comparison.

[billswan]

I have an st-5 from Ga Gen (Tom Osborne).  I am about to buy a PM gen head from him in the next few days.  Although I don't have any plans to implement any fuel use tests, or even carefully detailed power output, I will gladly give my general novice impressions of both after I receive it and put it through a few hours of use.  Looks like I may be the first on this board to get one from him. 

Looking forward to the comparison.

Welcome aboard bschwartz

Yes by all means there are many here that would like feed back on a PM head.

Please take pix, yes I know there are some pix on the net but more are better.

Even better would be pix of your head disassembled.

billswan

[bschwartz]

There are times when my wife wants to rip my head off..... but disassembled?

[rcavictim]

I would advise not attempting to take a PM head apart just out of curiosity and/or to take photographs.  I suspect a special jig will be reuired to pull and re-insert the armature as there will be potentially damage causing magnetic pull involved and acceleration of the rotor to stator that could cause an accident and damage.

[bschwartz]

I plan on pulling mine apart as long as billswan is offering his fingers (I'm kind of attached to mine).

I assume all references to pulling a PM head apart are all made in jest.  I think we all realize the tremendous forces involved.

[bschwartz]

Just bit the bullet and ordered a 6.5 K head from Tom.

[billswan]

Yes guys after some thought I agree it would take a jig to get a pm head apart and together without damage.

Sometimes my brain has a brownout. But my guess is most here would love to see the insides of a PM genhead. At least I would.

Billswan

[flywheel]

I will soon be starting assembly of small genset using a 3kw PMG from George B. at www.utterpower.com   It will be powered by the Perkins 402-c 05 mini diesel, serpentine belt driven and engine operated at a reduced rpm.  Stay tuned!  flywheel

[mobile_bob]

i for one am looking foward to seeing your project develop
and i am liking how this forum is filling out too

bob g

[rcavictim]

I have an oddball PM alternator.  It is made in England (that goes a long way to explaining this).  There is a big metal plate that says it is made with UniFied Threads.  Well gee I hope so.  This means the bolts are the same thread as the nuts right?     It is old school so does not have neo magnets.  specs are:

1.2 kVA
1800 RPM
340 volts single phase, 3.5 amps
1200 Hz.  Yes that's twelve hundred Hz.  Must be lots'a poles!  

I am thinking of putting it in my wind turbine as that auxiliary starter battery charger power supply.  After a step down xfmer and rectifier this will be able to put 50 amps into a 24 volt battery bank.  It could also support some CFL or LED tower lighting.

I would love to get one of those PM alternators you guys are talking about here for this machine.  I want to install a smaller secondary alternator that will make useable power when there is not enough wind to wake the big boy up.  3-4 kW would be ideal.

[bschwartz]

I AM !!!!!!!!!!!!!!

Just got up and running on the 6.5 K PM generator head from Tom Osborne!
Voltage droop seems less than the ST-5.  Flicker is slightly less, although still there due to the 6/1 power pulses.  No groaning when one leg is loaded higher than the other.  Unlike the ST-5, voltage DOES NOT SWING when only one leg is heavily loaded.  I LIKE IT !!!  Microwave sounds better and so does the hot tub pump.  Let the questions begin........

[BruceM]

One thing about the PM heads-  they have the cleanest AC output of any genhead in terms of high frequency EMI, they have zero conducted EMI.   

On all other heads it's caused by the diode bridge. Even the brushless heads.

[mobile_bob]

Bruce:

you mention the conduction of emi from the diodes?

i am most interested in that which is conducted from the diodes on brushless units
the ones where the diode is mounted within the rotor.

are you stating that the diodes conduction properties (switching) can end up impressed
onto the output of the stator? or rather impressed onto the 60hz sinewave?

the reason i am interested is i am getting some wierd switching crap being impressed onto the rotor
with a specific brand of regulator/controller that ends up being impressed onto the stator output,
which makes it onto the DC output after the AC is rectified.

sort of like a transfomer effect ontop of the normal generator function.

this is something i am trying to document, and will work to explore and illustrate on an oscope when i get
to feeling better again.

Bschwartz:

you are powering with a 6/1, can you tell me how many kwatts the pm head will deliver over that of an st5 from your engine?
sort of an comparative test of efficiency, where if you get for instance X watts from the ST head at max output of the engine
and now either X-300watts or X+300 watts from the pm head.

where in this case if X = 3000, then in the former case (x-300) the pm head would be approx 10% less efficient, and in the latter
10% more efficient.

i doubt there is a huge difference but i am very interested if there is any difference and particularly how much.

also, how much voltage does the head produce at no load and how much at full engine load

basically  _________ volts @________ hz , no load
and       _________ volts @ ________ hz , full engine load

with that we can determine that particular heads regulation at that point in the curve, figureing that you can
get 3000 watts from it with the 6/1,

it would also be nice to see those numbers at 4, 5 and 6 kwatts output, but we would have to wait for something
bigger for a 6/1 to get those.

if at all possible, and if you would do the test
it would be very useful if you could do the test listed above at perhaps
1kwatt, then 2kwatt, and then at 3kwatt so a curve might be established

i for one am very interested in such a report on any pm head, having not seen such to date, and
hearing all about the virtues of such machines. i will have to check utterpower.com George may have
posted a similar test i can't remember just now on his head. iirc it holds its voltage very well up to and
beyond its 3kwatt rating up to about 4 kwatts, but i am not sure.

thanks to both of you

bob g