Power sag question
Oct 22, 2008 at 2:39 PM Thread Starter Post #1 of 7

flashnolan

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I get power sags (not brown-outs as those are from the power utility) every time my refrigerator compressor turns on. There is a noticeable dimming of the lights in any room of the house when this happens. I am pretty sure this is due to a bad or non-existent ground in the electrical wiring. Since this is an apartment I can't rewire the electrical.

To my question: I am thinking about plugging the refrigerator into my UPS. When the compressor demands more power it will pull it out of the battery. From researching a conservative guess is that the compressor pulls about 20 amps during start up since motors pull more power until they get going. Do you think I would just pop the fuse in the UPS every time? What if I got a large enough UPS? Has any experimented with connecting a large Cap (like 1 Farad) like is done in a car stereo for a sub woofer?
 
Oct 22, 2008 at 9:32 PM Post #3 of 7

flashnolan

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Quote:

Originally Posted by Omega /img/forum/go_quote.gif
Why bother? Fridge-o-phile? :wink:


Because it bugs me everything time I see the lights go dim (about once an hour). Also, when the voltage drops to low levels it can shorten the life of electronic devices.
 
Oct 22, 2008 at 9:39 PM Post #4 of 7

beerguy0

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Quote:

Originally Posted by flashnolan /img/forum/go_quote.gif
Because it bugs me everything time I see the lights go dim (about once an hour). Also, when the voltage drops to low levels it can shorten the life of electronic devices.


Most electronic devices are designed to run over a range of voltages, usually 110-120VAC (at least). Unless your voltage is dropping significantly below that, I don't think you have much to worry about. You may want to hook up a DVM or power monitor to an outlet and see what your voltage actually drops to when the fridge kicks on. It may not be as bad as you think.
 
Oct 22, 2008 at 9:45 PM Post #5 of 7

flashnolan

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Quote:

Originally Posted by beerguy0 /img/forum/go_quote.gif
Most electronic devices are designed to run over a range of voltages, usually 110-120VAC (at least). Unless your voltage is dropping significantly below that, I don't think you have much to worry about. You may want to hook up a DVM or power monitor to an outlet and see what your voltage actually drops to when the fridge kicks on. It may not be as bad as you think.


There is a 10% tolerance built into most devices. I doubt a case can be made that a frequent dropping (however small) can be a beneficial thing for an electronic device. I was reading around about this to see if anyone else has tried it. Low voltage is definitely not a good thing as it makes the devices work harder.
 
Oct 24, 2008 at 3:47 PM Post #6 of 7

beerguy0

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Quote:

Originally Posted by flashnolan /img/forum/go_quote.gif
There is a 10% tolerance built into most devices. I doubt a case can be made that a frequent dropping (however small) can be a beneficial thing for an electronic device. I was reading around about this to see if anyone else has tried it. Low voltage is definitely not a good thing as it makes the devices work harder.


I was thinking about this last night, and the only thing that sees the line voltage is the transformer. I've done tests of this nature with a variac, and as long as the transformer puts out sufficient voltage to keep the regulators running, the devices in the box (amplifier or whatever) will see only the regulated voltage. Unless you're in an actual brownout condition, the devices in the box should never even know if the line voltage drops a little.
 
Oct 24, 2008 at 4:24 PM Post #7 of 7

Gollie

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The power coming about your wall is really dirty. It constantly browns out even if you don't see the lights dim. Your high end electronic equipment need to be on UPS battery back up at all times.

Your devices might have a 10% tolerance but the frequent voltage dropping can be devastating. UPS' are cheap (really cheap when compared to replacing equipment).

APC and Cyberpower make good units.
 

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