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[TCML] Re: Variac troubles

Hey Chris, Single phase, single core, everything isolated.Once I saw there was an issue, I limited my variables by disconnecting everything and running one core, but yes I do have paralleling chokes.Perhaps I need to try on a 50A breaker. But if the sound is any indication, I dont believe that to be the issue. I've never encountered a unit that made a buzz as loud as this one. Even at steady state with 6ohms in series it was loud as heck. Really need to instrument up some CTs and monitor current during an attempt... -JaySent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Chris Reeland <chrisreeland@xxxxxxxxx> Date: 8/8/21  12:04 PM  (GMT-05:00) To: tcml@xxxxxxxxxxxxxxx Subject: [TCML] Re: Variac troubles Hi Jay,Not sure if I can really help yet...But are you running this on single phase or 3 phase input?Not clear with info you gave so far.If 3 phase supply, what is the type exactly?So if using single phase, did you rewire the 3 cores and get and use the 3required chokes?You are already on the expected inrush when they are big like this andvarious methods to try to deal with this... but if there is a problemelsewhere?Are you using just "standard residential" breakers?There are industrial motor delay types available, but not likely to be thesame type to fit into a standard residential breaker box. So would requirea different high main supply branch and then these motor delay breakers init's own breaker box.So a few more details needed and a few suggestions from me here.And I am sure some others more knowledgeable on variacs will soon chimein...Chris ReelandLadd IL USASent from my Samsung Galaxy Tab® SOn Sun, Aug 8, 2021, 7:39 AM jhowson4 <jhowson4@xxxxxxxxxxx> wrote:> All, I would like to pic your brains. I acquired a stacco 5010-3Y, its> labeled as a 240V 3 phase unit set at 0-280 out. 50A per core. Only 3> terminals per core. Clearly marked. I'm running it on a 30A breaker at the> moment. With no load you'd think that would be fine. Sounds great, except I> can't get the darn thing to operate. Pops the breaker every time. Makes a> hellacious 60hz hum in the process on all the cores. This is with it> connected to nothing on the output, just applying voltage. Logically I> checked for anomalous resistances, everything showing proper> isolation.Visual inspection doesn't show anything noticable, Brushes and> contact surface looks good. One of the cleaner units i own..  Inrush> current seemed to be the next logical thing to try, got a 35A CW rated> varistor 2 to.02ohms (i only wanted to run these at 30A for the time> being)  which promptly exploded.  A relay shorting a high power 6ohm> resistor was the next step. Powered on at 240v with series resistor for> about 5 seconds then kicked on the relay to remove the resistor, bzzzzzzz> pop goes the breaker. No magic smoke or smells of burnt enamel.> Unfortunatly I havnt been able to observe the actual current its drawing> yet. But I will set up a scope in the near future to record it. I've> brought many variacs back into service, as have many of you. But this is> the only one thats been a real head scratcher. Next step is to pull the top> plate and see if anything is going on in the middle with the connections,> but alas Its not like I'm reading any shorts. There are 3 little inductors> or something that seem to be inside each core. I assumed they were on each> input/output to act as a current limiter of some sort.  But ill have a> better look when I pull the cover and go over a core with a fine toothed> comb.Anyone have any ideas of what I could be looking for or potential> causes. What ever the matter is, it seems to effect all 3 cores. Unclear if> the effect is equal on each core, but the result is the same. -Jay> _______________________________________________> Tesla mailing list -- tcml@xxxxxxxxxxxxxxx> To unsubscribe send an email to tcml-leave@xxxxxxxxxxxxxxx>_______________________________________________Tesla mailing list -- tcml@tcml.pupman.comTo unsubscribe send an email to tcml-leave@xxxxxxxxxxxxxxx
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