Looking for a special UPS


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Old 12-23-04, 12:39 AM
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Looking for a special UPS

I'm looking for a special UPS model. I have several computer in a spare room right now running on a single dedicated outlet circuit that used to be for a window air conditioner before central air was put in. Fortunately I do get plenty of air conditioning in the room. But I don't get enough power. The outlet circuit is 120 volt 20 amps. The rest of the outlets are shared with other rooms, and only 2 computers are on there.

The problem is, I need to add about 8 more computers in the next few months. Running new wiring is not an option (this is not my house). What is an option is upgrading the existing dedicated circuit from 120 volts to 240 volts. And that would be enough power.

I also need to get a larger UPS. My existing one doesn't even handle what I have now, so only 5 computers are on UPS. I need about 2400 watts in a new UPS. The big catch is I need to down convert that 240 volts to 120 volts for the computers. I priced some transformers, and they are quite expensive, nearly as much as a similarly sized UPS.

The type of UPS I want is a dual-conversion online type. This is the type that constantly converts AC to DC, parallels with the batteries, and back to AC again. I've looked through several manufacturer web sites and found they make UPS models for both 120 volts and 240 volts in the size I need. But they don't make any with 240 volts in and 120 volts out until around 10 kilowatts. My thinking is that if I can find a UPS in my size range (2400 watts) with 240 volts in and 120 volts out (or a 120/240 volt split with a neutral) then I can avoid the cost of a separate transformer.

The wiring is 12 AWG, so it's limited to 20 amps. At 120 volts that won't be enough. SInce upgrading the wiring is out, the 240 volt route is what I am looking at.

I just need to find the right UPS. Has anyone seen something like that in the 2400 watt range?
 
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Old 12-23-04, 04:46 AM
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You are in over your head.

You need to add new wiring. Trying to use the existing wiring for 240 volts and then stepping down to 120 volts is not an appropriate solution.
 
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Old 12-23-04, 06:42 AM
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I agree and I never even hurd of a 2400 watt UPS. Am I in the dark? Are these new?
 
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Old 12-23-04, 08:27 AM
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Originally Posted by racraft
You are in over your head.

You need to add new wiring. Trying to use the existing wiring for 240 volts and then stepping down to 120 volts is not an appropriate solution.
It's not my house and the situation is temporary. Doing new wiring is an option that has been taken off the table.
 
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Old 12-23-04, 08:43 AM
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Originally Posted by Terminator20
I agree and I never even hurd of a 2400 watt UPS. Am I in the dark? Are these new?
I don't know how new, but I have seen UPSes around the 2400 watt range that come in 120-in/120-out versions (have a 30 amp plug and need a 30-amp circuit, which I cannot do on AWG 12 wiring), and in 208-240-in/208-240-out versions (without a neutral that would be needed to get 120 volts directly). The higher voltage versions omitted the cord and plug and have a hardwarded terminal base for input which I can wire in a cord and NEMA 6-20P plug.

The exact wattage isn't required. I figure something from 2000 to 3000 watts might do. I've seen 2700 and 3000 watt models that do 240-in/240-out at 60 Hz. I could add a step-down transformer before or after the UPS (depending on what voltage UPS I get), but that transformer at that size tends to cost nearly as much the UPS itself ($2000).

Much of the detail of how I would go about this would be on the Electrical forum, but the critical point at the moment is trying to find that elusive UPS that converts 240 volts AC to some voltage DC, and converts that DC back to 120 or 120/240 volts AC. For that I figure maybe this Computer forum would more likely have encountered it.
 
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Old 12-23-04, 08:46 AM
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Once you find such an animal, it will cost you more to purchase and use than it will to redo the wiring.
 
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Old 12-23-04, 09:35 AM
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Originally Posted by racraft
Once you find such an animal, it will cost you more to purchase and use than it will to redo the wiring.
I have to agree with Bob on this one.

Chris
 
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Old 12-23-04, 09:58 AM
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tripp-lite has 5000 watt system.

http://www.tripplite.com/selector/re...CFTOKEN=830528

Also many/most computer have a switch on the back to run them on 240 volts.

Powervar has many 208-240 models that all put out 120 volts. They range from 2400va to 18kva

http://www.powervar.com/English/Solu...rod_ups_sp.asp

google '240 volt ups -ebay'
 
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Old 12-23-04, 01:33 PM
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APC Matrix UPS does what you are asking about

We have an APC Matrix UPS that runs five (average ~eight hard drives, all at least dual proc.) Servers, plus a Promise storage array and three tape drives. Of course, it's also a huge unit, and I'm not sure how many AMPs it pulls.

It takes 240 volt input, and provides two 120V "circuits", each 20AMP.

This suckers expensive, but hey, you didn't ask for price. These are highly expandable units, so they may be more reasonable with fewer batteries (ours has enough to keep everything above running for about 40 minutes).
 
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Old 12-23-04, 01:37 PM
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BTW: Are you using KVM switches, or does each system have its own keyboard/video/mouse? If you are not using KVMs, you can save significant power (and space) in doing so by eliminating lots of monitors.
 
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Old 12-30-04, 04:59 PM
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As already mentioned, most power supplies have a switch tol take a 240v input (and use half the amps doing so).

I would suggest, rather than 1 large UPS, you use several smaller ones. I've had no problems running 2 or 3 machines (complete with ancient CRT monitors) on an APC BX1500. While I am certain they make it, that large of a ups that is also capable of shutting down each machine is NOT going to be cheap (around $1500).

As a contrast, the BX1500 is only $200.

For $800, running 2 machines on each, you'd have your UPS.
 
 

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