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
