6kva liebert ups

[mobile_bob]

a friend of mine dropped off a rather large ups unit about this time last year, and i finally decided i needed
to process the thing so i can make room for the next round of... whatever it is i am doing

it has a 192vdc front end buss, and i decided to take stock of what i might have to drive it with
and turns out i have enough to make up a 192volt bank with 17amp/hr batteries, the originals were 12amp/hrs
so these would have to sit outside the case.

now when it comes to stringing together a 192volt dc bank of batteries, this is something that requires ones complete
and undivided attention, 48 will bite you, 96 will shock the crap out of you, and i don't even want to know what that is like
at this stage in my life.

after carefully making the connections between 16 batteries, and connecting two anderson plugs in mid string, and another pair
to feed the ups, i was set to go.

i connected the plug to the ups, and then taking a big deep breath and holding it, like you do for an xray,, i closed my eyes
and made the connection.

hmmm, nothing,, cool

went and tried a cold start, and found the unit dead as a door nail

tried every combination of switch positions and still no joy.

so to the salvage bench to dismantle for goodies.

there are 3 toroid transformers inside about 5" outside diameter, complete with temp switches attached,

not sure of their rating, but might make a useful set for some other project.

lots of other very large parts, nice heavy rectifier bridges, some huge caps, and a bunch of other stuff.

i have come to the realization that is something doesn't work, and cannot be easily fixed, it is either going to be parted
out and dispensed with or given away.

can't hardly wiggle and i am getting tired of not having room to bend over and pick up something dropped on the floor.



bob g

[BruceM]

High voltage DC does give me concern, especially for smoke tests.

I fried some parts on my 120VDC regulator a couple nights ago-  a not-so-brilliant addition to reduce power consumption and tighten zener regulation involved a TO-92 package P-channel MOSFET switching a tiny amount of +120VDC (nominal).    Pop- fizz, smoke!

I had goofed and violated the gate to source max voltage spec.  When the MOSFET failed it sent 141V back on the gate, frying a 1/4 watt resistor, a dual micropower op amp and a gate driver chip. Whoops!  141V running around a  12V board where it's not supposed to be is very destructive!

Sorry your big Liebert didn't fly, Bob, but it sounds like you'll get some nice parts. At least there were no loud noises and smoke.

[mobile_bob]

it certainly wasn't without much puckering, when i made the connection via anderson to anderson plug

i really wasn't worried so much about magic smoke, as much the blinding flash and related explosion
followed closely by the brown stuff running down my legs



i am no stranger to smoke, but the big bang you never really get used to.

bob g

[BruceM]

I'm a fan of the Anderson power pole connectors, too.  Alliedelec.om now stocks them. 
They have some  PCB mount ones now too.  They were (and still are) very popular with RC electric powered flight 20 + years ago, where compact, very high current connectors were needed.

I can only use a DC soldering iron now- so don't get use the nice stuff for IC extraction; it's clip every lead on the chip and then pull out every pin, one at a time...

It will help remind me to study any "brilliant" late night circuit changes very carefully before smoke testing.

[Geno]

I just found out about the Anderson connectors last week while surfing to find a good connector for my projects. Today I received 10 sets of 10gauge and another 10 of 8 gauge. It looks like they will do what I want nicely.

Powerwerks.com had good prices.

Thanks, Geno

[mobile_bob]

well the liebert is no more...

it is now a nice pile of goodies that will find a new life in other projects

got 4 nice toshiba dual igbt's, 3 nice sized toroid chokes, 3 rectifier bridges and 2 larger bridges,
and a pile of current transformers which will come in real handy as circuit sensors.
an a couple huge dc caps, and some ac caps as well.

and about a cup full of screws!

my collection of goodies is beginning to look like a nice sized power electronics erector set.

lots of stuff to make smoke with

bob g

[potter]

Ive got a large collection to , sure wish i knew how to make other than smoke matches are faster.