RE: [CAD_CAM_EDM_DRO] Home shop power for a big machine

I've been following this thread for a while. When I trained as an electrician, VFDs were not available here in France (twenty five years ago). Three phase electricity is pretty readily available, (I have 18Kw that I can have set to 36Kw just for a day if I phone the Electricity company!) I don't need VFDs that create three phase. With large motors, to overcome the "spike" at start-up, Star-Delta systems are used on three phase motors. would this be possible with a phase converter or is the spike in the converter? A technical thought!

Matthew TINKER

CNC conversion 1944 Colchester Lathe build-up log

http://www.cnczone.com/forums/showthread.php?t=35519

To: CAD_CAM_EDM_ DRO@yahoogroups. comFrom: elson@pico-systems. comDate: Wed, 31 Dec 2008 13:03:29 -0600Subject: Re: [CAD_CAM_EDM_ DRO] Home shop power for a big machine



vrsculptor wrote:> I was lusting over a big VMC that would never fit in my home shop and> got to wondering about power. The machine's data plate says 230 volts> 3PH @ 80 AMP's, 18KVA. It has a 15 HP spindle. >> I could use a rotary phase converter to generate the three phase but> don't have anywhere near 80 AMP's available. 18KVA/750 watts equals a> 24 HP phase converter.>> If you where using this machine in a hobby environment and not trying> to get production feeds and loads how small of a phase converter could> you get by with?> I think even with 200 A service in a typical home, you are really pushing it! The line current into a typical rotaty phase converter is going to be REALLY high with a machine like this. If you trip the breaker out on the transformer, the power company is going to get QUITE nosy about what you are doing. If you have your own dedicated pole transformer, you might get away with it. Especially if the local setup has a 50 KVA
transformer on the pole. If you have a 25 KVA transformer shared between 4 residences, you will NEVER get away with it, and you'll have a bunch of angry neighbors, too.It is possible that the machine really doesn't need 3-phase at all. If the servo drives are PWM (not phase-controlled SCR) they may run fine on single-phaee power. If a VFD is used for spindle speed control, it may be able to run off single phase at reduced output.Jon



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