We run into this at farms and grain elevators that often have 240 or 480 3-phase. We are on the grain leg at one farm where there is only the 3 legs no neutral. We checked with Phoenix Contact and the power supply we used can accept L1 and L2 on the terminals labeled L and N (actually a Trio DC UPS, this is an old old site). Not sure how common this is, or if our Mean Wells and Tracos would get fried if we tried that. I wish they wouldn’t label one side N if it doesn’t actually have to be the neutral.
Most of these sites have an indoor transformer for their 120V lighting and convenience outlets. From: AF <af-boun...@af.afmug.com> On Behalf Of Chuck McCown via AF Sent: Monday, January 8, 2024 3:55 PM To: AnimalFarm Microwave Users Group <af@af.afmug.com> Cc: ch...@go-mtc.com Subject: Re: [AFMUG] -48V kicking the dead horse Another option, 208 Y but 32 volt boost transformers on devices that need 240. Have done that before too. I always consider boost and buck a slick trick. From: Chuck McCown via AF Sent: Monday, January 8, 2024 2:43 PM To: AnimalFarm Microwave Users Group Cc: ch...@go-mtc.com <mailto:ch...@go-mtc.com> Subject: Re: [AFMUG] -48V kicking the dead horse You a few choices for 3 phase mixed with 120 single phase. Stinger center tapped winding on a Delta lets you have single phase 120/240 between two legs of the delta. But this also means you have 240 three phase all the way around where many 3 phase loads are nominally spec’d at 208. Probably not a problem but could be for some loads. You also have one leg that is 208 to ground that you might accidentally connect to a 120 device. That is the high leg. Another choice is a 208 Y configuration. Each leg is 120 to ground but two of those 120 legs are 208 across them instead of 240. While many 240 loads will be OK with 208 some will not. All your 208 3 phase loads will be happy. The third choice is a 208 to 240 center tapped transformer. Then your 208 can stay 208 and you can still get true 120/240. The only downside other than the extra expense is the imbalance it puts on the 3 phase line. My shop is full of transformers. 480 to 208. 480 to 240 single phase. Etc. Or you could have the power company give you 3 phase and single phase service without all of this other baloney. From: Mark Radabaugh Sent: Monday, January 8, 2024 2:18 PM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] -48V kicking the dead horse On Jan 8, 2024, at 1:54 PM, Ken Hohhof <khoh...@kwom.com <mailto:khoh...@kwom.com> > wrote: What I always have a hard time wrapping my head around is 240/120/208 wild leg delta. I don’t think that one is hard to understand, other then the ‘why the hell did someone center tap a delta let anyway? Ok, I have designed systems that way but eventually somebody will blow something up with it given enough time. (it’s useful when you need small quantities of single phase power in an otherwise 3 phase system) Mark _____ -- AF mailing list AF@af.afmug.com <mailto:AF@af.afmug.com> http://af.afmug.com/mailman/listinfo/af_af.afmug.com _____ -- AF mailing list AF@af.afmug.com <mailto:AF@af.afmug.com> http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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