I would look for something 9 KVA or larger. Going bigger really doesn't hurt, and if you want to use the full capabilites of the machine and add up a 7.5 KW spindle, then add in say .75 KW for each axis (2.25 KW), then add in any other motors coolant pump, rtc, then bump that up by 3-4 you should be close to the minimum required KVA for full power operation. You will need more KVA capacity than the total KW of your drives due to the power factor of the drive which honestly is probably pretty bad since they really didn't care about power factor much back then. A 12-15 KVA transformer would not be too big. Some manufacturers start their drive isolation tranformers sizes at about 11 KVA, I have no idea why.
Dave On 5/30/2012 1:31 PM, John Thornton wrote: > I'm guessing I don't need near that size perhaps 9-10 KVA? > > John > > On 5/30/2012 12:20 PM, Dave wrote: > >> On 5/30/2012 12:34 PM, andy pugh wrote: >> >>> On 30 May 2012 17:15, Dave<[email protected]> wrote: >>> >>> >>> >>>> Perhaps I missed something; Did you figure out if that transformer in >>>> your machine is a Delta-Wye transformer or not? >>>> >>>> >>> It seems to be an autotransformer with a common centre tap (pretty >>> much identical to the hypothetical one I described). >>> There is low resistance between every combination of terminals, >>> including both input and output to neutral. >>> >>> That, plus the advice from Siemens, does seem to hint that swapping >>> the existing step-up transformer for one with a neutral tap in the >>> secondary is the way to go, though. >>> >>> >>> >> Ugh... I missed the "autotransformer" conclusion. I thought this was >> some type of autotransformer/transformer combo. So the machine builder >> saved $100 by using an autotransformer.. Geez. >> >> Yep, I would find a Delta-Wye transformer and ground the Wye center. >> >> With the high price of copper these days, transformers are going for >> premium prices. >> >> This guy really has his prices set high ... perhaps he would entertain >> an offer? I don't think these will sell for the asking price. >> http://www.ebay.com/itm/Marelco-30KVA-60Hz-3phase-Transformer-230-240-460-480-Volt-Delta-380-400-Y-Wye-/180816467318?pt=BI_Circuit_Breakers_Transformers&hash=item2a19805576 >> >> You might want to try Uship.com if you want to get one of these >> transported. I have had good luck with that service. Just be picky >> about who you select. >> >> 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. Discussions >> will include endpoint security, mobile security and the latest in malware >> threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ >> _______________________________________________ >> Emc-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > ------------------------------------------------------------------------------ > 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. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ 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. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
