Right now I have a 10hp rotary converter and a 15hp rotary phase converter. The discovery has a 7.5hp or so spindle so it would take more than a 7.5 hp single phase motor.
I don't run the mill all day long everyday but off and on... The upshot of have a diesel generator wired up is I would have emergency back up power enough to power the whole house. I have a 40hp tractor but the problem with the PTO generators is the lack of coupling between the generator and the governor on the tractor which would not make it a reliable source of power for me. Not to mention I'm only 3 years older than the tractor and I'm almost as old as dirt... John On 5/24/2012 11:51 AM, Dave wrote: > I've got a 10hp phase converter that I built in my shop. > > Some of the commercial units - there is still a maker in Indiana I think > - use basically the same thing that you and I have setup. > > But they cut off the motor shaft to keep it tidy. :-) > > The problem with a motor/generator setup is that you have single phase > power and the largest single phase motor readily available is about 7.5 > hp. Although I think I have seen a 10 hp single phase once. > > What are the power requirements of your machine? If it exceeds 7.5 hp > (or 10hp if you can find a big single phase motor), then an > Motor/generator setup is out of the question. > > Here are two: > http://www.ebay.com/itm/new-in-crate-SINGLE-PHASE-10-ten-HP-Horse-power-1745-Rpm-Electric-Motor-NEW-/170560823989?pt=LH_DefaultDomain_0&hash=item27b637a2b5 > http://www.ebay.com/itm/Leeson-Motor-131848-00-7-5-10-HP-single-phase-Crop-Dryer-New-/250957251817?pt=LH_DefaultDomain_0&hash=item3a6e37c4e9 > > If you only run the machine for a limited time and you are doing fairly > high value work, you can probably justify running it off a generator. > Diesels with sound enclosures can be pretty quiet. > > Another idea, if you are only running it for short periods - if you have > a good size tractor with a PTO - perhaps a PTO genset would work? > I've seen those in size up to 50 KW or so, but you need a big tractor if > you have large power requirements. > > I've got a similar dilemma with my lathe that says it needs a 65 KW > service and I had to move it out of the shop it was in (they are in > financial trouble). I am going to try and get by with a 55 KW > generator until I can get > some steady business for the lathe (if I can find steady business for it) . > The generator I have is not in an enclosure but it is pretty quiet > considering its size, but it is not a diesel so there is no diesel > "clanging" which tends to drive people nuts (from my experience). > > If things go well, the lathe will be in a new building this fall, unless > I find some cheap commercial space nearby to rent which may be possible > since many businesses are still folding up it seems. > > Dave > > > > On 5/24/2012 11:05 AM, John Thornton wrote: >> I've built several rotary phase converters using plans from the web but >> they all seem to stop at adding a few caps to balance the voltage and >> the auto start circuit with the potential relay. >> >> Have you ever peeked into your commercial unit to see what else is there? >> >> John >> >> On 5/24/2012 8:41 AM, dave wrote: >> >>> On Thu, 24 May 2012 06:00:23 -0500 >>> John Thornton<[email protected]> wrote: >>> >>> >>>> Just to update the results of last nights test run of the cobbled up >>>> generator setup. While we had a devil of a time trying to make the >>>> diesel motor that we coupled up to the generator stay at 1800 rpm it >>>> stayed close enough for me to rapid my Z axis up and down at 295 IPM >>>> with the spindle turning 2k for about 5 minutes with no complaints >>>> from the Simodrive 611 despite the voltage varying wildly as motor >>>> powering the generator surged up and down. >>>> >>>> So now I have two options as I see it and option B is preferred due >>>> to the noise of running a diesel generator. >>>> >>>> 1) buy a 3 phase generator to run the shop. >>>> >>>> B) figure out how to make my phase converter put out a proper 3 phase. >>>> >>>> If anyone has any ideas on option B I'm all ears. I have a small line >>>> reactor (rated at 3hp) that I can put on the phase converter output >>>> and see what that does. I see claims of true 3 phase power from >>>> rotary phase converters when searching for rotary phase converter and >>>> cnc so there must be a way cause these claims don't seem to be coming >>>> from small time shysters. >>>> >>>> >>> <massive snip> >>> >>> I built a 5 hp phase converter and it was OK but not perfect. Plans >>> came off the net. One leg was maybe 20 v out. Been a long time and I >>> really don't recall. When I got the Mazak I wanted something better so I >>> sprung for a commercial unit. Ray Henry recommended an outfit in >>> Birmingham ( AL that is ). >>> I got a 30 hp unit. It is really close in voltage, a couple of volts >>> between phases. Inrush current on starting is massive but it has never >>> blown the motor starting fuses (125 A). Unfortunately the outfit either >>> went broke in the recession or they retired. >>> >>> Even a diesel gen set is an expensive way to get power unless you are >>> simply off the grid. As you said, they are noisy and also require >>> maintenance. >>> >>> If I had to do it again I think I'd give the home-built another shot. >>> There ought to be a way to auto-tune the phase under load. :-) >>> HTH >>> Good luck! >>> >>> Dave >>> >>> ------------------------------------------------------------------------------ >>> Live Security Virtual Conference >>> Exclusive live event will cover all the ways today's security and >>> threat landscape has changed and how IT managers can respond. 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