Do UPS's function as line conditioners?

zephyrprime

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Feb 18, 2001
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Do UPS's also function as line conditioners or do only line conditioners clean up ac lines?
 

NokiaDude

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Oct 13, 2002
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Some do, my old APC Back-UPS 500 says it has line filtering but I dont notice much of a difference other than my computer not shutting off when the power goes out :D Of course my house was built in the 80's and it seems to be built pretty well. I think line filtering is only needed if you have LOTS AND LOTS of electronic equipment that's putting static into the lines or if your power lines are crappy.
 

zephyrprime

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Feb 18, 2001
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There actually seem to be quite a few people that have bad lines but I have no idea what the percentage might be. My friend seems to have a higer than normal death rate for his hard drives so that's why I ask.
 

mechBgon

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Oct 31, 1999
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The line-interactive models will continually monitor the incoming voltage and trim or boost it as needed. As far as I know, non-line-interactive ones just watch for the voltage to drop past a certain point and then the switch to battery power.
 

woodie1

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Mar 7, 2000
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Originally posted by: zephyrprime
There actually seem to be quite a few people that have bad lines but I have no idea what the percentage might be. My friend seems to have a higer than normal death rate for his hard drives so that's why I ask.


I think I would suspect his power supply. The incoming line (no matter how much noise it has) should not impact the IDE devices if you have a decent PS.
 

zephyrprime

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Feb 18, 2001
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The line-interactive models will continually monitor the incoming voltage and trim or boost it as needed. As far as I know, non-line-interactive ones just watch for the voltage to drop past a certain point and then the switch to battery power.
So what models are line interactive?
 

mechBgon

Super Moderator<br>Elite Member
Oct 31, 1999
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The BackUPS Pro and SmartUPS models are fully line-interactive, with both boost and trim, according to APC's site. The BackUPS CS models have AVR boost, but not trim. At work we've got a couple of their SmartUPS 750XL's, which have big batteries plus can be expanded with additional battery modules for extended runtime if desired. But those are ~$500 UPS's.
 

zephyrprime

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Feb 18, 2001
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Well, I got an answer from a APC tech support person:

The Back-UPS line do not have line conditioning capabilities per say they output a step approxiamted sine wave when on battery and many of the Back-UPS do have automatic voltage regualtion. The Smart-UPS line have Network Grade line conditioning and full time EMI/RFI noise filters.
 

sharkeeper

Lifer
Jan 13, 2001
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True line conditioning is not available on the inexpensive models mentioned. To have true line conditioning, one must purchase a UPS with a ferroresonant transformer and they are not cheap nor found in a computer retail outlet. Try ebay and search for ferrups. Shipping on all but the smallest units is rather expensive as they are heavy.

Cheers!
 

pm

Elite Member Mobile Devices
Jan 25, 2000
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Before I purchased a UPS, occassionally turning on my monitor while my computer was running would cause my computer to reboot (presumably from the voltage drop caused by IR drop in the lines from the monitor's surge current). A UPS solved this problem completely, and the lights in the room are steady and the computer has never rebooted from the monitor switching on again.

I bought a relatively inexpensive model, and perhaps the effect that it has is not true line conditioning, but it does act to hold the input voltage steady in the event of voltage drops... as it was designed to do.
 

sharkeeper

Lifer
Jan 13, 2001
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A CRT monitor has high draw when first turned on because the thermistors in series with the degaussing coil are cold and the coil gets a lot of inrush. This is a reactive load which can wreak havoc with switching power supplies. It's quite different from the inrush from a large quartz halogen firing! Chances are the RF (LC or hash) chokes on the UPS were enough to prevent the switching PS on your PC from choking! (pun not intended)

Then again, without using a line analyser, it's hard to tell exactly what is going on. The important thing is the UPS solved your particular problem.

Cheers!