fusible link questions

[Don.F.Broadus at ucm.com]

Early Delco alt's had star wound stators since they give a high voltage at
low RPM. Then when current was needed in the mid 70's Delta stators were
used on 80 amp  27SI Alt's to give high current. I have read about a
Japanese Alt. that had a star and delta wound stator. The star had its own 6
diode bridge and the delta had its own 6 diode bridge. At low RPM the star
produced 14V and at higher RPM the delta provided the current. The text
stated that this was an attempt to have the best of both worlds. Motorcycles
have used PM rotors for years and controlled the output voltage with shunt
regulators. SCR's would be used ahead of the diodes to short the ac to
reduce the voltage. Other types shunted the DC thru a resistance to  ground
momentarily to keep the voltage constant. I remember an old Norton
motorcycle that regulated the alt with a large stud mounted Zener diode on a
large finned heatsink on the handlebars. Shunt regulation does cost in
efficiency but unless PWM  is used it is the only way to regulate a PM alt.


> -----Original Message-----
> From:	Clarence L.Snyder [SMTP:clare.snyder.on.ca at ibm.net]
> Sent:	Sunday, February 07, 1999 8:35 PM
> To:	diy_efi at efi332.eng.ohio-state.edu
> Subject:	Re: fusible link questions
> 
> Steve Sassine wrote:
> > 
> > On Sun, 7 Feb 1999, Justin Guest wrote:
> > 
> > > This could be quite useful if you controlled it properly. A lot of
> people
> > > spend a lot of money trying to increase 12v up to something useful for
> > > ICE. Does anyone know how to get an alternator to deliver higher
> > > voltages. I was looking at this sort of design with two alternators in
> > > mind one running at 12v and the other at a higher voltage. Its a long
> > > time since I did my HNC and I was not really interested in generators
> and
> > > alternators at the time.
> > >
> > > Sorry this is not about EFI but it is electronics.
> > >
> > >
> > > Regards Justin Guest
> > > Email as header or jg55776 at glaxowellcome.co.uk
> > > Phone +44 (0) 1229 482549
> > >
> > >
> > > >On Thu, 4 Feb 1999, Steve Sassine wrote:
> > > SNIP
> > > >
> > > >Canadain tire used to sell a box that would output 120 vdc from the
> > > >alternator. it just full fielded the alt and at around 1500 rpm 120 v
> > > >
> > > >scarry eh
> > > >
> > > SNIP
> > >
> > 
> >       It is not vary hard to also get 120 v ac at 50-60 hz. Remember
> that
> > most alternators are three phase sync motors. The Three phase output
> > voltage is rectified using a full wave bridge rectifier. This low
> voltage
> > output, say is is at 12v RMS, can be stepped up using a step up
> > transformer. You only need to by-pass the bridge rectifier. Also need to
> > check the sine wave for different higher order harmonics. This set up
> can
> > also regulate the ouput voltage.
> > 
> >  from steve sassine
> If you get 60CPS at 1000 alternator RPM, I'm sorry to have to tell you
> you won't get much output from it. The faster you spin it, the more
> output you get. Usually "geared" about 3:1 to the engine, at 2000 RPM
> coasting down the highway you are spinning the alt at about 6000 rpm,
> and producing 3 phase AC at360 cps. The 400CPS previously mentioned is
> AWFULL close to what you will see at highway speeds. If you want AC from
> an automotive alternator, just get a decent inverter.Spikes of current
> draw are buffered by your battery so you don't fry the alt, frequency is
> steady, as is voltage. You will likely pick up the inverter for less
> than it costs to convert the alternator to a useless piece of junk,
> assuming you value your time at anything over about 50 cents an hour.
> 
> I snagged a 1500 va unit from an old Bell Telephone truck for $75
> canadian dollars. That's about 50 US Greenbacks.