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burnt and no clue, UPS

hello, i had a merlin gerin 5 kva 31 series model ups for 3 phase to 1 phase. the arrangement from company manual said that the optional isolation transformer shall be at output side of ups it means a single phase 1:1 ratio xformer at ups output but by some ignorance i had a design as a

3:3 phase isolation Xformer at UPS input. The fuses inside ups are 10amp per phase and the battery is connected externally to have greater

back up times and charged by external charger which takes three phase input from primary of isolation Xformer. Odd enough!

the transfomrer burnt and this has to be investigated. the indications on ups diagnostics were unit was on static bypass units mains fuses were blown (we found r and b phase fuses were blown) units internal charger orand rectifier is/are damaged(internal charger was disabled i dont know how but internal ups battery and charger can support up to 8 mins so were disconneced by local supplier and this external battery with charger were added, battery was 60 amps each total 180 volts etc 12 * 15 may be) my Ac input is 440 volts delta and 230 volts in phase Neutral 50 hz. isolation Xformer is delta to star. the meger test showed insulation failure in Y phase for the Xformer primary and secondary. Dhananjay

Reply to
bandyaggroup
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Too many volts. Too many amps. Too few cycles. DC running through windings. Those are the reasons to look for.

N
Reply to
NSM

one more observation, the UPs systems do not take neutral etc and the three phsaes when have a fuse blown in any phase shall see a overload for other two and the protection device shall trip etc in my acse this did not happen and the two phases had a fused line still third y phase could take current so much as to make the transformer burn etc so it looks that it found path through neutral to complete the circuit etc the neutral if i do not use the ups shouldnt have taken current from y phase is it so?

D
Reply to
bandyaggroup

Dammmm what a run-on sentence!!! I'm not trying to be a grammar cop here, but that conglomeration of words made my eyes hurt while trying to piece together what you're trying to say. Please try again, but use a modicum of punctuation. You'll likely get more meaningful answers to your question (whatever it was).

--
Dave M
MasonDG44 at comcast dot net  (Just subsitute the appropriate characters in 
the address)

Never take a laxative and a sleeping pill at the same time!!
Reply to
DaveM

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