I'm working on a 12v 75AH x 5 (ie 60v) ups hooked up to 10 PCs but when the mains power goes off computers go off b4 coming back some times some of them stays on whiles the rest go off. Can someone tell me what is wrong and what I can do. Thanks.
If it really IS a UPS then it shouldn't be a case of "switching on fast enough"
- it should be running continuously and supplying the load from the rectified line input. In that case, I'd suspect the rectifier/battery system voltage is at fault, allowing the DC in to the inverter to droop when the load is to be supplied from the battery system. This could also be a battery condition issue.
If the "UPS" in question isn't actually continuously inverting to provide the output AC, then (without getting involved in a semantic flame war) it is far from an uninterruptible supply. You can't afford a "short break" on supplying your load. Get a real one.
Make sure you are not overloading the UPS with the 10 computers. You need to have a UPS rated for at least 4KVA minimum for 10 pentium based computers.
Then you also need to make sure that all of the computers are in fact plugged into battery backed up outlets. Most properly functioning UPSs that do not run all the time even when ac is present will be off a maximum of 10 cycles, or 1/6 of a second which is plenty fast enough for recovery of any computer power supply.
Some server power supplies have an AC sense and will go into a fast shutdown even if there is an interuption of 1/6 of a second. So you also need to make sure this feature is disabled on the computers if they have it or replace the UPS with one that provides full isolation and is constantly running, like the $8000 ONEAC largest unit.
You may be overloading the UPS, the batteries may be a bit weak, or the UPS is not fast enough for your needs. The most common causes of your description are weak batteries, or the UPS is overloaded.
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JANA _____
I'm working on a 12v 75AH x 5 (ie 60v) ups hooked up to 10 PCs but when the mains power goes off computers go off b4 coming back some times some of them stays on whiles the rest go off. Can someone tell me what is wrong and what I can do. Thanks.
No. UPS come in 2 flavours: on-line (like you describe) and off-line (as OP obviously has).
You may only like the on-line variant (and with good reasons, mostly) the majority of entry level UPS is of the off-line type. (And even that may be a favourable situation, given their mtbf :-)
-- Kind regards, Gerard Bok
I agree, but the nomenclature here seems to reserve the "uninterruptible" term to the on-line types. Let's face it, the off-line devices aren't a no-break system, so it's a bit of a stretch to call them uninterruptible when there IS an interruption.
hence my comment "If it really IS a UPS.."
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