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bad liebert ups

i got a 6kv liebert ups, trips the dc breaker on testing fail to backup

never worked on a ups before, i can say the ac side seems to be ok, and the charger seems ok as the batteries stay floated /charged front pannel lcd seems to work

any clues what might be a good path to start on or perhaps someone might know what these ups typically blow?

thanks

Reply to
ml
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Reply to
M Berger

yeah thanks v much, usually they are pretty good, wish i had the manual, at first i figured perhaps i didn't set it up right, but the place that discarded it said the repair guys said it wasn't worth repairing. the batteries for sure are fully charged and float ok

if it's not getting ac, it won't ever power it just shuts off, fooling w/the pannel trying to 'turn it on' dc testing etc just trips the breaker(dc)

appreciate the tips i'll poke around a bit more

Reply to
ml

ml wrote in news: snipped-for-privacy@news.verizon.net:

backup

might

Most UPS's are pretty simple.

  1. AC line voltage flows into the UPS and straight to the load.
  2. AC line voltage also charges storage batteries.
  3. When AC line voltage fails, an AC inverter starts up
  4. AC inverter draws DC power from the storage batteries
  5. AC inverter delivers AC power to the load
  6. When AC line voltage comes back on, go back to 1.

So you have some pretty simple systems to analyze and troubleshoot.

You say the batteries seem to be fully charged, which probably means the charging circuit is working and maybe even the batteries are OK.

You say the DC breaker trips and it doesn't put out any power under backup mode. So you've isolated the problem to the DC wiring and the input of the inverter circuit. Try disconnecting some cables and see if you can isolate the short circuit or low-resistance circuit that's drawing too much current. If it turns out to be the inverter, take it out, open it up, and start looking for shorted components.

Good luck!

Reply to
Jim Land

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