Hi Elvis
On (02 Aug 96) Elvis Hargrove wrote to Alec Cameron...
-> windings so that a second three phase supply was given, out of phase
-> with the other. The particular connection was called ZIG ZAG or
-> SCOTT,
 EH> Now, how'd they do THAT!  I'd be quite interrested in having six phase
 EH> available for an arc welder.  Voila!  No sputter!
Easily done. The transformer has two independent secondary windings on each 
leg
of the iron core. A half winding on Red phase is series connected to a 
imilar
half winding on Yellow. And so on. This gives 7 terminals- the star point, 
nd
three phases [the junctions, plus three more that are shifted 30 degrees to
the former.  Presto! Six phases.
This is a standard but rare, connection that you'll find in the NEMA and ASA
Codes for power trannies.
-> The steel tank version, came with a vacuum pump to keep the internal
-> chamber de- gassed.
 EH> Astounding!  How hard a vacuum?  How deep was deep enough?
Hey, I was a teenager. I had other things on my mind! Vacuum would
occasionally "fail" and there would be a back- flash, essentially a short. 
he
rectifier [one of several] would trip, pause and restart. The trains would 
keep
right on running as many substations fed the same trolley wire.
As you are feeling some disbelief! I must tell you that each tank anode had a
back- flash "recorder". This was a metal ramp of dished section, with a steel
ball resting at top in a wee concavity. The magnetic force due to a backflash
would roll the ball off its seat and we would find it later at the bottom of
the ramp. A rectifier that lost its balls too often was due for maintenance 
f
the anodes, or of the vacuum pump.
-> And the steel tank, being at rail potential [not
-> perfectly earthed] was supported on insulators.
 EH> I LOVE it "Earthed!"  How Droll, eh wot?
Well, this was a serious business. I have recorded rail- to- earth voltages
exceeding 120 volts. Train shunters would get nasty jolts sometimes as they
uncoupled freight cars.
The Sydney Harbour Bridge is insulated from the rail tracks that carry 1500v
dc trains across it. For good reason, maybe you will work that out!
                                                                   
-> Are you sorry you asked?
-> A synchronous motor I guess! With a neat, durable cam shaft and
-> adjustable cam followers to drive the DC side commutating switches.
 EH> Well, I'll be dipped and dabbled around!  Only yesterday I was
 EH> poo-poohing such a suggestion.  You're pulling my leg now aren't you?
 EH> The six phase part I underrstand.  Cam driven contacts even at 50 cycles
 EH> is a bit much.  Getting them adjusted to zero crossing must've been a
 EH> BEAR!  Nah, you're having me on......
I tell you true. Sorry I never worked on the gear but I was told that the
noise level was spectacular. 50 Hz is no great achievement, the old fashioned
buzzers worked around 200 to 3000Hz. To make a rotary switch to spin for 50 
Z
one needs only 750 to 3000 rpm depending on how many contact pairs per rev.
Now think of the design of auto and cycle engines, to spin with precise valve
timing at 10 000 to 15 000 rpm, with varying speed not synch speed!
 EH> Obviously electron flow is vastly different in OZ......
Well, we have the Borealis [solar wind] and interruptions to radio and phone
and power systems, but much less severe than you do in the far north toward
Canada.
A HOMEPOWER option- Free Loader. Used by [very few] utilities to power tower
top aircraft warning lights, in isolated spots.
An insulated  conductor run beneath, and well clear of, a HV line conductor
will receive AC power thru air capacitance. Transformed down to a safe 
oltage
and rectified to charge a battery there is free energy.
No power Co would agree to you doing this though. And you would be foolish to
run your wire too near the HV wires.
Maybe the technique will someday be provided to rural customers eg on huge
ranches, provided the energy requirement isn't too great.
It must be very dangerous though, as a severe shock is possible from even a
short length of insulated wire. The antenna wire would need to be kept
grounded until the installation was finished. Some rather fancy protective
features are no doubt, fitted to the engineered version.  Cheers...ALEC
... .....Never Underestimate the Power of Invincible Stupidity!
--- PPoint 1.92
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