Thanks, John R. Crane
On Mon, Mar 21, 2011 at 7:27 AM, John Thornton <bjt...@gmail.com> wrote: > John, > > I'll dig out my schematic and make sure it is up to date and figure a > way to post it to the list. > > John > > John Crane wrote: > > John, > > > > I would like to know more about the way you have engineered your phase > > converters. I am in the process of adding this capability in my shop. > > > > Thanks, > > > > John R. Crane > > > > On Thu, Mar 17, 2011 at 5:53 AM, John Thornton<bjt...@gmail.com> wrote: > > > > > >> I have three rotary phase converters. The are all using a potential > >> relay for the start caps and a relay that pulls in the mains. So I don't > >> have to hold the push button and if the power drops out for a few > >> seconds the phase converter does not try and restart without the start > >> caps. I've not had the fun of blowing anything up when building them. > >> They are all balanced phase to phase within a couple of volts. However > >> phase to phase the run caps are very different in order to get the > >> voltage phase to phase to balance. I can post some details if anyone is > >> interested... > >> > >> John > >> > >> Dave wrote: > >> > >>> Back when I put my 10 hp phase converter together, I found some charts > >>> on the web someplace about suggested capacitor sizing. I found a > cheap > >>> supply of capacitors at Mendelson's in Dayton, Ohio > >>> and bought a small box of them. I ended up using I believe, 4 - 330 > uf > >>> 330 volt units as starting caps and 4- 135 uf run caps. I use a push > >>> button to start the motor and as long as I hold the button > >>> down the starting caps are wired into the circuit. When the motor > spins > >>> up I release the button. I tried to use a voltage sensitive relay, > >>> like the ones used on refrigeration systems and AC systems, but > >>> it was not reliable probably due to the high current from the large > >>> number of caps. There is also a motor contactor that seals itself in > >>> via the button push. That way if the line power drops, the contactor > >>> drops out and the converter idler motor and he > >>> attached slave motors are powered down. > >>> > >>> The math relating to how this works gets even more complicated when you > >>> consider the effects of hooking a 3 phase motor that you are going to > >>> start (a slave motor) across the the idling phase converter motor. > >>> For a brief period of time, the idler motor becomes a generator. The > >>> rotor slows slightly and the energy in the rotor pumps power into the > >>> three phases and spins up > >>> the slaved motor. It works very well. > >>> > >>> During experimentation, it is very obvious when more starting > capacitors > >>> are required as the motor will simply not spin up. > >>> Adding more run caps helps balance the phases but they never really > >>> fully balance. > >>> > >>> Safety glasses are very good idea when experimenting. Starting caps > >>> go off like firecrackers if you overstress them. They are only > >>> designed to be switched in for a few seconds. > >>> > >>> A source of cheap starting caps is a really good idea if you want to do > >>> some phase converter experimentation. I blew up several of them. > >>> > >>> Dave > >>> > >>> On 3/14/2011 9:01 PM, Jon Elson wrote: > >>> > >>> > >>>> > >>>> > >>>>> On 14 March 2011 10:50, John Thornton<bjt...@gmail.com> wrote: > >>>>> > >>>>> > >>>>> > >>>>> > >>>>>> Is it not amazing that the hillbillies from backwoods Missouri with > a > >>>>>> 3rd grade education can make a rotary phase converter without all > the > >>>>>> math... > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>> > >>>>> > >>>> Of course! The trick is the windings in the motor do all the math for > >>>> you, all you need to do is hook up the wires. > >>>> > >>>> Jon > >>>> > >>>> > >>>> > >> > ------------------------------------------------------------------------------ > >> > >>>> Colocation vs. Managed Hosting > >>>> A question and answer guide to determining the best fit > >>>> for your organization - today and in the future. > >>>> http://p.sf.net/sfu/internap-sfd2d > >>>> _______________________________________________ > >>>> Emc-users mailing list > >>>> Emc-users@lists.sourceforge.net > >>>> https://lists.sourceforge.net/lists/listinfo/emc-users > >>>> > >>>> > >>>> > >>>> > >>> > >>> > >> > ------------------------------------------------------------------------------ > >> > >>> Colocation vs. Managed Hosting > >>> A question and answer guide to determining the best fit > >>> for your organization - today and in the future. > >>> http://p.sf.net/sfu/internap-sfd2d > >>> _______________________________________________ > >>> Emc-users mailing list > >>> Emc-users@lists.sourceforge.net > >>> https://lists.sourceforge.net/lists/listinfo/emc-users > >>> > >>> > >> > >> > ------------------------------------------------------------------------------ > >> Colocation vs. Managed Hosting > >> A question and answer guide to determining the best fit > >> for your organization - today and in the future. > >> http://p.sf.net/sfu/internap-sfd2d > >> _______________________________________________ > >> Emc-users mailing list > >> Emc-users@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/emc-users > >> > >> > > > ------------------------------------------------------------------------------ > > Colocation vs. Managed Hosting > > A question and answer guide to determining the best fit > > for your organization - today and in the future. > > http://p.sf.net/sfu/internap-sfd2d > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > ------------------------------------------------------------------------------ > Colocation vs. Managed Hosting > A question and answer guide to determining the best fit > for your organization - today and in the future. > http://p.sf.net/sfu/internap-sfd2d > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Enable your software for Intel(R) Active Management Technology to meet the growing manageability and security demands of your customers. 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