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| Thread ID: 58413 | 2005-05-31 05:26:00 | Uninterrupted power supply - recommendations? | Tony (4941) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 359959 | 2005-06-01 00:04:00 | actuall biff brings up another point. when buying UPS's check what baterries they use. not all use standard batteries so replacements can be very exspenicive. | tweak'e (69) | ||
| 359960 | 2005-06-01 01:39:00 | 750 kVa would be enough to supply around 200 houses. Like a subdivision or a major street area. Whoops, take out the k in there. :lol: Would 750va be enough for my system? |
E|im (87) | ||
| 359961 | 2005-06-01 08:23:00 | Interesting thread. | vapo (5203) | ||
| 359962 | 2005-06-01 08:35:00 | Whoops, take out the k in there. :lol: Would 750va be enough for my system? Should be plenty. My 400 vA has 1 P4 2 GHz, 1 GB RAM, 2 x HDD, 2x optical drives, FDD, card reader, GF4 MX460, TV card, Network card, 2 x 19" LCD monitors. Not only will it run the lot for 4 or so minutes, but it will actually cold start the system with the power plug removed. A cold start is not a requirement but it is probably maximum power draw. |
godfather (25) | ||
| 359963 | 2005-06-01 11:18:00 | Suffice to say that APC is the brand of choice - even though I have no more to say on the matter. | Growly (6) | ||
| 359964 | 2005-06-01 11:42:00 | Thanks. :) See on the UPSs around when they say 800VA/540W (www.ascent.co.nz) is 540W the maximum load it can take? What if the devices attached are drawing more load than that? | E|im (87) | ||
| 359965 | 2005-06-03 07:43:00 | ^ | E|im (87) | ||
| 359966 | 2005-06-03 08:05:00 | No way we can comment on the surge ability and individual load characteristics . You find out when you buy it and connect it . There is such a thing as diversity, when you have multiple devices connected . They don't all draw their rated maximum at once . The VA rating is more important than the wattage, as the power factor of PC supplies is poor . VA is greater than watts in the normal case . If a device has a power factor of (say) 0 . 7, and is rated at 200 watts, it draws 200/0 . 7 = 286 vA . Its hard to measure vA and power factor without a power analyser, hence the inability to answer the question with any degree of accuracy . We also have no idea of the diversity of the load at any instant . |
godfather (25) | ||
| 359967 | 2005-06-05 12:01:00 | Thanks godfather. If I may rephrase the question slightly, I'm trying to determine what "Output power capacity: 540 Watts" means. What does it mean? Lets say the system isn't running off the batteries and main power is good. If my PC uses say around 600 Watts or something can the UPS supply enough power or will it only supply 540W to it? |
E|im (87) | ||
| 359968 | 2005-06-05 23:17:00 | That tells me its good for 540 watts only when supplying battery backed power . Not when in mains mode . But it does not say if that is the instantaneous wattage (inrush at switch-on for instance) . If you overload the UPS it will instantaneously shut down, but ONLY if its running on the UPS batteries (for the cheaper type of UPS) . If on the mains supply, the UPS is not even in circuit or interested in the load, it just does not know what is being drawn until its asked to come on line by a mains failure . That takes a few milliseconds only, its very quick . More expensive "on-line" UPS are different, all load is supplied by the batteries which are constantly charged by the mains . They do care about the load all the time, but they are not under discussion here (very expensive) as I see it . But I doubt that you really have 600 watts (or anything near it) after diversity . |
godfather (25) | ||
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