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Need some help with Uninterrupted Power Supplies

ApostateApostate PrinceSpaceRegistered User regular
I have an issue right now where certain high power items will occasionally draw enough power to cause my computer to lose power momentarily and occasionally trip the breaker. It's not possible to change the item configuration up right now. I do have an uninterrupted power supply that picks up but it does so too late. I know it works as it picks up fine if there is an outside outage. Is there a UPS that will keep power going even when the breaker trips or there is a short high power drain?

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  • matt has a problemmatt has a problem Points to 'off' Points to 'on'Registered User regular
    edited August 2012
    UPS's... UPSes? are supposed to do that already. Do you know the brand/model you have?

    This is probably overkill for your application, but I use this at work. It keeps two PCs, a modem, router, 8 port switch, monitor and KVM powered for about 30 minutes if there's an actual blackout, and covers just fine for momentary power drops.

    matt has a problem on
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  • ApostateApostate Prince SpaceRegistered User regular
    edited August 2012
    See I thought the one I have should have protected against a breaker trip as well. It just never has. Assumed I just needed a better one. The model I have is a http://www.amazon.com/CyberPower-CP550SLG-Standby-550VA-Desktop/dp/B002QAUN2M

    Apostate on
  • DjeetDjeet Registered User regular
    If you're drawing enough power to trip the breaker (assuming 15 amp at 120V) then your UPS is woefully inadequate for your demands. Using "VA" as shorthand, you want 1800 VA minimum (typically your overbuild by 20%, so 2160 VA). If it's a larger circuit (which it might be in a non-residential application) you might be dealing with 20 amps.

    FYI, UPS's are not meant to be used in this capacity. Code would likely demand you deliver a new circuit (15 or 20 more amps), though if you wanted to skate by that get more sophisticated power regulation (which will cost more than putting in another circuit).

  • SiliconStewSiliconStew Registered User regular
    As said you either need a much larger UPS or you need to get the high draw items off the existing one. Your UPS is only rated at 330 watts (2.75 amps @ 120V) and you're trying to power stuff that will trip a 15-20 amp breaker? Buy a power strip and run the high draw stuff off that if you can't get proper protection.

    Just remember that half the people you meet are below average intelligence.
  • ApostateApostate Prince SpaceRegistered User regular
    So then just to clarify the only thing hooked up to the UPS battery is my main monitor and computer. The surge only part of the UPS has a small speaker system, another monitor, and a desk lamp. The UPS is using the upper outlet plug and the high drain thing (a portable AC) is using the lower plug. So its not on the UPS. Sorry if that wasn't clear.

    It's when the AC turns on initially that there is a power drain (lights dim briefly and the like). A couple times this has caused my computer and monitor to lose power for an instant without even tripping the breaker. I would have thought the UPS would prevent that since it has a battery back up. I know the battery was working as of a few months ago as there was a widespread power outage and the battery picked up fine when the power went out.

  • DjeetDjeet Registered User regular
    It sounds like the switching logic on the UPS is just trash, or a component (like a capacitor) has failed or is failing. Have you tried (while the computer is on and plugged into battery backup) just yanking the UPS power cord to the outlet and seeing what happens? It should go straight to battery power, if not then chances are good the UPS is trash. If it does go to battery backup during current interruption then there's some issue with the switching logic such that a power sag does not trigger the switch to battery power.

  • electricitylikesmeelectricitylikesme Registered User regular
    Apostate wrote: »
    So then just to clarify the only thing hooked up to the UPS battery is my main monitor and computer. The surge only part of the UPS has a small speaker system, another monitor, and a desk lamp. The UPS is using the upper outlet plug and the high drain thing (a portable AC) is using the lower plug. So its not on the UPS. Sorry if that wasn't clear.

    It's when the AC turns on initially that there is a power drain (lights dim briefly and the like). A couple times this has caused my computer and monitor to lose power for an instant without even tripping the breaker. I would have thought the UPS would prevent that since it has a battery back up. I know the battery was working as of a few months ago as there was a widespread power outage and the battery picked up fine when the power went out.

    It sounds like you need a new UPS, because it definitely shouldn't be letting the computer die during a brown out - that's like, 95% of what a UPS is supposed to protect you against (hell it's a whole market - failover power while you wait for a big diesel generator to kick in).

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