Interestingly I had a bit of time last night and did some more voltage measurements with various bits turned on to load the RPC.
RPC only running AB=245 BC=253 AC=253 With the BP 308 (Simodrive 611) powered up AB=245 BC=245 AC=245 With the Samson 7.5hp manual lathe spindle at 660 RPM AB=244 BC=232 Adding the 308's spindle at 1000 RPM AB=244 BC=234 AC=229 Ramping up to 3000 RPM on the 308's spindle AB=244 BC=234 AC=227 So it appears I need to do a bit more tuning with the caps as the load is dragging down the voltage on the generated leg. Interestingly with the Samson running the BP 308 would start from 0 to a higher RPM than with it off even though the voltage had been pulled down by the Samson's spindle. I also tried adjusting some of the pots on the 611 spindle drive with no conclusive results from that experiment. I did hear back from the transformer guy Gene gave me the link to. Seems to be a fair price so I'll investigate that more as well as look at the diesel generator next week and do some more tuning on the RPC. "Hi John, The cost for a 240 VAC 30A 3-phase isolation transformer is $1250. Factory lead time is approximately 4-5 weeks. If you need any additional information or would like to order the unit, please feel to contact me by phone or email. Regards, Jeff Jeff Weinberg Harbach Electronics, LLC" John On 5/30/2012 2:58 PM, Dave wrote: > I think the reason why they want a grounded neutral is to keep the phase > voltages controlled relative to a ground reference. > > The drive chassis usually has several large ground lugs on it which are > suppose to be tied to earth ground as would be the neutral. > > An ungrounded Delta power system can get out of control relative to > earth ground. For instance, if for some reason one leg of a Delta goes > to ground, the other two legs rise to a voltage equal to the line to > line voltage away from ground. If you get an intermittent short between > one Delta leg and ground, the voltages can swing all over the place > relative to ground. > That stresses any parts in the drive system which are referenced to > frame ground. Back in the early 90's Siemens had one line of VFDs that > had big problems blowing DC link capacitors. I was told that was > because they were being used on ungrounded delta systems (used to be > very common in industrial plants in the US) and if the Delta power > source got out of wack, the capacitors would see high voltages to ground > and explode. I saw a couple of them that literally blew apart the > drive. That line of VFDs was short lived and they quickly changed > their design. > >>> From the tone of the tech's voice he hears this problem a lot with 611 > drive and rotary phase converters.<< > > The 611 drives are very popular. Many machine manufacturers used them for > many years. Those guys have pretty much heard it all. > > Dave > > > > On 5/30/2012 3:19 PM, John Thornton wrote: >> When we ran the generator we connected the 3 hots as usual and I don't >> recall if we grounded it or not. I only had 3 connectors large enough >> for the leads coming out of the generator so I'm sure we didn't connect >> the ground to the neutral of the generator. >> >> http://cache.automation.siemens.com/dnl_iis/DA/DA0NDQzAAAA_59401543_HB/PJU_0212_en.pdf >> >> In that manual after a fault I have 4 status LED's lit up. On page 6-143 >> the bottom 4 LED's are lit. Which one caused the fault I can't tell. >> >> The machine schematic does not show a neutral connected at the stepup >> transformer and the infeed unit doesn't even have a neutral connection >> and neither does the machine. >> >> From the tone of the tech's voice he hears this problem a lot with 611 >> drive and rotary phase converters. >> >> John >> >> On 5/30/2012 1:12 PM, Jon Elson wrote: >> >>> John Thornton wrote: >>> >>>> I just got off the phone with Siemens tech support and "Our systems >>>> don't run well on phase converters." >>>> >>> Well, given the way this system works, I'm not surprised by his comment. >>> But, it is fairly close. You need to get into it and see WHICH trip it is >>> getting. There probably are several different sensing circuits >>> (over-voltage, >>> under-voltage, lost phase, etc.) and knowing which one is the source of the >>> trip should be VERY helpful. Right now you are flying blind, not >>> knowing whether >>> it needs more or less voltage, etc. >>> >>>> was the main theme of the >>>> conversation as well as we can't run on a Delta system because we need >>>> the ground reference I think he said. >>>> >>>> >>> But, does the machine bring out the neutral? I think you said it does >>> not, so >>> his comment does not make sense. Well, given the way this system works, I'm >>> not surprised by >>> >>>> Additionally he suggested a Delta to WYE step up transformer with >>>> grounded secondaries between the RPC and the 611 >>>> >>> Well, if there's no neutral brought out, that doesn't make sense. If it >>> is SUPPOSED >>> to have the neutral connected, and the wire has been removed when it was >>> supposed to be connected, then suddenly, a LOT of things start to make >>> sense. >>> >>> If it needs a neutral connection, it may be possible to connect it to a >>> balance >>> transformer, which is three windings on one core, with all the wires at one >>> end connected together as the neutral. >>> >>> When you used the Diesel generator, did you hook the neutral to something? >>> You said you used the 208 V taps, was this generator a 120-208 Wye >>> unit? If it worked fine on the Diesel with NO neutral connection, then >>> this has no bearing on the problem. If you DID hook the neutral to >>> something in the machine, then this may be the most important piece of >>> data. >>> >>> Jon >>> >>> ------------------------------------------------------------------------------ >>> 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. 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