burnt and no clue, UPS

[[email protected]]

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

 

[Art]

Overload or a very nasty switching spike? Post your total diagnostics and
required repair component information. Rather interesting.

 

[NSM]

the transfomrer burnt and this has to be investigated.

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

N

 

[[email protected]]

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

 

[DaveM]

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

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!!