[TheForge] 15Ton Press
Ed Fasula
[email protected]
Tue Jan 8 22:26:01 2002
Hi Steve,
I'll definitely let ya'll know about it if I do it that way ...
Ed
>Well that's interesting. It seems like if you get more work out of the motor,
>there has to be more current involved, but maybe not. Please let us know what
>happens.
>
>Steve
>
>Ed Fasula wrote:
>
> > Hi Steve,
> > 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
> >
> > At 09:44 PM 1/6/02 -0700, you wrote:
> > >Ed, I don't see any way that a VFD will convert a 3HP motor into a 5HP
> motor.
> > >What you said below is correct; "the motor's output torque will meet or
> > >exceed a
> > >5hp 3600 rpm motor to satisfy the demand of the pump". The problem
> with it is
> > >that when you are pulling 5HP out of the motor shaft, you will also be
> pulling
> > >5HP worth of current in the windings. The windings are only sized for
> 3HP, and
> > >you will fry them pretty quick. Am I missing something here?
> > >
> > >VFD's are nice (well, the only way) if you want to vary the speed of
> an AC
> > >motor.
> > >
> > >Steve
> > >
> > >Ed Fasula wrote:
> > >
> > > > Hi Steve,
> > > >
> > > > I think it kinda cool that if I start out with an 1800 rpm 3hp
> motor and
> > > > use the VFD to double the speed to 3600, the motor's output torque will
> > > > meet or exceed a 5hp 3600 rpm motor to satisfy the demand of the
> pump. (I
> > > > only need 2.5hp to run at 1800 so 5hp will handle double the hp of
> the pump
> > > > at 1800.) The local motor repair place does it often. I can get a
> 5hp VFD
> > > > factory refurbished for the same price as a new 3hp VFD (about
> $360). So
> > > > I'll start with one of the 3hp motors I got and if that's not
> kosher for
> > > > whatever reason I'll scrounge or buy a used 5hp for $80.
> > > >
> > > > The other option would be to make a phase converter and run a 3hp
> motor I
> > > > have. Say $80 for the extra motor plus $70 for the phase converter
> > > > electronics (I think - correct me if I'm wrong). So I'm paying
> $210 for
> > > > the ability to run the wood splitter and tune-in the speed of my
> press. I
> > > > also have thoughts about wiring a switch in that would allow me to
> use the
> > > > VFD to run the power hammer motor. I've always wanted to play with
> the rpm
> > > > of that thing.
> > > >
> > > > All in all, I don't know if it's wise or not, but it seems worth the
> > > > experience and possible benefits. If I don't have to do anything
> exotic
> > > > with my cylinder porting I'm getting off pretty cheap on this press
> so the
> > > > extra $210 doesn't make me whine to much.
> > > >
> > > > Ed
> > > >
> > > > >If you double the speed, you also double the HP required out of
> the motor.
> > > > >I don't
> > > > >know if this is a wise idea.
> > > > >
> > > > >Steve
> > > > >
> > > > >Ed Fasula wrote:
> > > > >
> > > > > > Hi Steve,
> > > > > > I'm thinking that I'd like the variable speed so that I can double
> > > speed
> > > > > > the motor for splitting wood or if I want to go
> quicker. Thanks tho.
> > > > > >
> > > > > > Ed
> > > >
> > > > _________________________________________________________
> > > > Do You Yahoo!?
> > > > Get your free @yahoo.com address at http://mail.yahoo.com
> > > >
> > > > _______________________________________________
> > > > http://mailman.qth.net/mailman/listinfo/theforge
> > > > theforge mail list group photo site is
> > > > http://albums.photopoint.com/j/AlbumList?u=1169182
> > > > ___________
> > >
> > >_______________________________________________
> > >http://mailman.qth.net/mailman/listinfo/theforge
> > >theforge mail list group photo site is
> > >http://albums.photopoint.com/j/AlbumList?u=1169182
> > >___________
> >
> > _________________________________________________________
> > Do You Yahoo!?
> > Get your free @yahoo.com address at http://mail.yahoo.com
> >
> > _______________________________________________
> > http://mailman.qth.net/mailman/listinfo/theforge
> > theforge mail list group photo site is
> > http://albums.photopoint.com/j/AlbumList?u=1169182
> > ___________
>
>_______________________________________________
>http://mailman.qth.net/mailman/listinfo/theforge
>theforge mail list group photo site is
>http://www.photoaccess.com
>___________
_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com