[Home][2021 Index] [TCML] Re: Variac troubles [Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[TCML] Re: Variac troubles

Hi Jay,

These are indeed individually 120v variacs by the part number.
Look at the 5000 series Staco catalog for specs when 5021's are used 3ph Y
vs. your 5010's(now 5011).
So of course when 5010's combined 3ph Y they are now (become capable) 240v

And currently thinking no on the 208v single phase and just one Variac.

3 phase is a bit different "beast". I will admit I am now a bit "rusty" at
3 phase, since leaving the printing industry for good a few years ago.

Not sure currently what to make of the "little transformer cores" your

Chris Reeland

Sent from my Samsung Galaxy Tab® S

On Sun, Aug 8, 2021, 8:06 PM jhowson4 <jhowson4@xxxxxxxxxxx> wrote:

> Ok,Im thinking Bert is correct. I was infact able to power on at 120v. I'm
> curious now if I can power it up at 208 (ie the line to neutral voltage in
> a 240Y system) kind of odd to have a part number implying 120 operation,
> but a label implying 240v operation.I think ill call the company and ask
> for more info. Note: after peaking under the hood,this variac has no
> additional taps.The name plate is obvious,Simple diagram,  3 screw lugs.1
> wired to the beginning of the coil2 is the wiper3 is wired at about 75% of
> the coil1 and 3 are connected to the strange little transformer cores,
> which arnt paralleling chokes (no interconnection to the other cores) I'll
> update again with any useful info I may find. -JaySent from my Verizon,
> Samsung Galaxy smartphone
> -------- Original message --------From: Bert Hickman <
> berthickman1@xxxxxxxxx> Date: 8/8/21  3:10 PM  (GMT-05:00) To:
> tcml@xxxxxxxxxxxxxxx Subject: [TCML] Re: Variac troubles Hi Jay,Try
> running them off 120 volts to see if they operate correctly.Although I
> wasn't able to find the specs for your specific variacs, Staco does show
> what may be a similar version (5011-3Y). Deciphering the part number
> suggests that your ganged variacs may be actually be configured to operate
> off 120 volts. Staco's variacs often have a variety of terminals/taps that
> allow them to be configured for operation in various single-phase and
> 3-phase modes and ganged for higher currents.The chokes are likely
> "paralleling chokes". These are are actually small transformers that are
> used to balance slight output voltage differences when multiple variacs are
> connect4ed together to increase output current and eliminate unwanted
> circulating currents between paralleled variacs.Once you remove the covers,
> you should be able to rewire them to operate of 240 volts by changing
> jumper settings. The Staco web site has lots of information that you may
> find useful.Good luck!BertOn 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@tcml.pupman.comTo unsubscribe send an email to
> tcml-leave@tcml.pupman.com______________________________________________Tesla
> mailing list -- tcml@tcml.pupman.comTo unsubscribe send an email to
> tcml-leave@tcml.pupman.com_______________________________________________Tesla
> mailing list -- tcml@tcml.pupman.comTo unsubscribe send an email to
> tcml-leave@xxxxxxxxxxxxxxx
> _______________________________________________
> Tesla mailing list -- tcml@xxxxxxxxxxxxxxx
> To unsubscribe send an email to tcml-leave@xxxxxxxxxxxxxxx
Tesla mailing list -- tcml@xxxxxxxxxxxxxxx
To unsubscribe send an email to tcml-leave@xxxxxxxxxxxxxxx