They really don't have to be, but they should probably both be larger than 10 KVA. If you have one that was 30 KVA and another that was 10KVA, I wouldn't hesitate to hook them together for a test.
Although if you can trip out your 611 with only the spindle running and ramping up slowly, even a couple of 7.5 KVA transformers would probably prove out the situation one way or another. Dave On 5/31/2012 3:15 PM, John Thornton wrote: > I might be able to scrounge another 240-480 transformer and put it with > the one I have to get back to 240... do you think they need to be > similar in size? > > John > > On 5/31/2012 11:28 AM, Dave wrote: > >> Looks to me like it is more like a $1264 question. ;-) >> >> I don't know. That's why I would try and borrow one first. >> >> Know of any plants where you do work that has a spare transformer lying >> around? >> >> I've put a couple of them together before to get the right voltage.. IE >> 240 to 480 and then 480 to 380 etc. >> >> Dave >> >> On 5/31/2012 12:06 PM, John Thornton wrote: >> >>> I just ran another program to drill and tap a slew of holes in a 1/2" >>> steel plate with no problems except for I picked the 5/16-18 tap and >>> drill for the 1/4-20 holes and proceeded to tap all 8 of them at the 20 >>> TPI pitch... no biggie I'll tap them out to 3/8 and plug them and tap >>> them over again. >>> >>> $64 question will the isolation transformer do the same thing the 7.5hp >>> spindle motor is doing on the Samson? >>> >>> John >>> >>> On 5/31/2012 9:43 AM, Dave wrote: >>> >>> >>>> You are probably right. When the drive load surges it is likely faulting >>>> out on what it thinks is a lost phase or phase undervoltage. >>>> >>>> It might be interesting is to run this test again and put a clamp on >>>> ammeter on each leg feeding your Mill and see how balanced the currents >>>> are. >>>> >>>> I have never really had any problem with my phase converter running >>>> loads so I haven't paid much attention to it, but I think I only have >>>> run capacitors connected between one phase and the made up phase. I >>>> know I don't have any >>>> between both of the two original phases. I was always more concerned >>>> about the current balance between phases than voltages. The voltages >>>> have always been within reason ( as I recall ). But then this is one >>>> of those things that I don't pay much attention to unless it isn't working. >>>> >>>> I suspect that the 611 is expecting a stiff power supply - which most 3 >>>> phase services can provide. If you have a large pulley you can attach >>>> to your phase converter motor shaft to add inertia to the rotor, you >>>> might want to attach it. It would help the motor supply surge current >>>> to the 611 drive. >>>> >>>> Dave >>>> >>>> >>>> >>>> On 5/31/2012 10:04 AM, John Thornton wrote: >>>> >>>> >>>>> A little update this morning after last night's experiments I built on >>>>> that a bit this morning. I upped the MFD's on the B-C and A-C caps a >>>>> little at a time till I got close to what I think I wanted in voltage. >>>>> This is what I ended up with... >>>>> >>>>> Phase ===========> A-B B-C A-C >>>>> Caps 50MFD 100MFD 220MFd >>>>> RFC on 246v 263v 271v >>>>> Samson @440 RPM 246v 247v 249v >>>>> 611 Drive on 245v 243v 241v >>>>> Engraving @6k RPM 244v 243v 234v >>>>> >>>>> I grabbed a program at random an it turned out to be engraving my >>>>> company logo at 6k RPM. Now mind you this was not 0 to 6k but 0 to 2k >>>>> with a 0.09 second pause between 100 RPM increases up to 6k. To my >>>>> surprise the program ran to the end without a fault including rapids at >>>>> 295IPM on the Z axis. When I go to town I'm going to snatch up a few >>>>> more caps to play with and bump up A-C a bit more to try and even it >>>>> out. This will at least allow me to make parts for the time being until >>>>> I either get an isolation transformer or generator. The interesting >>>>> thing that I discovered is if I start up the Samson lathe with the 611 >>>>> on I get a fault and have to reset the drive. This leads my tiny brain >>>>> to think that it is a voltage drop to some degree that is tripping out >>>>> the 611... what do you guys think? When my neighbor gets around to >>>>> showing me how to store the traces in the scope I'll try and capture the >>>>> wave form when this happens. >>>>> >>>>> Thanks for all the help and ideas. >>>>> >>>>> John >>>>> >>>>> ------------------------------------------------------------------------------ >>>>> 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 >>>>> Emc-users@lists.sourceforge.net >>>>> 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 >>>> Emc-users@lists.sourceforge.net >>>> 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 >>> Emc-users@lists.sourceforge.net >>> 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 >> Emc-users@lists.sourceforge.net >> 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 > Emc-users@lists.sourceforge.net > 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
