[TheForge] 15Ton Press

Mon Jan 7 13:33:01 2002

I stand corrected in this instance...so you are saying, that you are
applying voltage/current to MORE windings and causing the motor to go
slower?

  Jeff   ><>

----- Original Message -----
From: "Darrell" <[email protected]>
To: <[email protected]>
Sent: Monday, January 07, 2002 1:30 PM
Subject: Re: [TheForge] 15Ton Press

> You are mixing 2 pole/4 pole motors with power supplies. A 2 pole
motor has two
> separate windings and that is what causes the motor to run at 3600
RPM.
> (60cycles per second times 2 = 120) how many times a second the
current changes
> direction (120 times 60 seconds = 7200) number of changes per minute
(7200 / 2
> poles= 3600) speed of a 2 pole motor. (7200 / 4 = 1800) speed of a 4
pole motor.
> Certain losses cause the actual speed to be closer to 1725 RPM.
> Darrell
>
> http://www.machinemaster.com
>
>
> ----- Original Message -----
> From: "Jeff Harding" <[email protected]>
> To: <[email protected]>
> Sent: Monday, January 07, 2002 5:41 AM
> Subject: Re: [TheForge] 15Ton Press
>
>
> > 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
> >
> >
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