[TheForge] 15Ton Press

[Jeff Harding]

Hi All;

   I can't speak to the VFD, I haven't looked into it and I admit to
being un-informed, BUT, I can speak to "phase" electricity.

   When you have a three phase or even 220V motor it is set up to take
current from two or three different sources, at the generating
facility there is at least three dnynamos if they are producing three
phase.   Each  phase is from a separate alternator and 220 volt, as
most of us have in our homes, is just voltage/current supply from two
separate sources,  stepped down to "110" volts each to enter your
house. ( actual voltage on my lines runs 121-125 , can't complain
until it's a 10% over voltage, I checked it out, that means 120 +
12... at 132, then I can complain.)

   SO... compare it to one guy pushing a car, "in three pieces", he is
still applying the same force but in three places on the back of the
car.   NOW... two other guys join him,   still only one guy pushing on
each spot, but three times the push... that is how I would analogize
it.

   Make sense?

   Jeff   ><>

   BTW... the same electricians that call 220v "two pole" , will call
three phase, "four pole".. .they count the neutral when considering
three live lines and don't count it when, " It's just 220"... In other
words...Same thing guys, 220v is two live lines from separate
alternators and a neutral, three poles...  "three phase" is three
lines from separate alternators and a neutral, four poles.... why they
do that is maddening to me..

   I'm sure there is some true 4 phase and maybe even higher in some
large urban industrial areas, but not enough that many have actually
touched "4 pole"....

> The reason is that a 5hp 3600 rpm motor is a 2-pole and the 3 hp is
a 4-pole.
>
> Now I could stop there and maybe sound smart, but I'll go on to say
that I
> don't really understand it.   It' what the guy said.  I guess the 4
points
> give you more field for your current but i dunno.  :^)
>
> It sure sounds like gettin' something for nothing to me too, but I
talked
> with a good chief electrician and a motor repair shop I've worked
with for
> a long time and they both thought there is some truth to it, but
they
> weren't really sure how far you could push it.  The guy who wants to
sell
> the VFD says they do it all the time with the farmers.  He
guarantees it'll
> work or he'll take the VFD back.  Anyway, if I go that way I'll get
a VFD
> that can handle a 5hp motor just incase.  If I fry one of the two
3hp
> motors I got for free, I'll chalk it up to cheap tuition.
>
> Ed