[TheForge] 15Ton Press

Mon Jan 7 13:43:59 2002

You can also have a different configuration of the armature to get different
motor speeds.
Darrell

http://www.machinemaster.com

----- Original Message -----
From: "Jeff Harding" <[email protected]>
To: <[email protected]>
Sent: Monday, January 07, 2002 10:31 AM
Subject: Re: [TheForge] 15Ton Press

> 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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