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Air conditioner in room with PC bad?


tal ormanda

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If I have my air conditioner in the same room as my PC, when it kicks in it makes the lights flicker (voltage loss?). Is that harmful for my PC and other devices plugged in inside the same room? AC is on its own outlet and PC and other things are on the other side of the room (plugged into surge protectors).

Edited by tal ormanda
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Yes it sound like your AC Unit is initially drawing faster than what is made available when it turns on, causing a mini-brown out. Its possible that using a larger circuit could fix that, or making sure the AC unit is on a different circuit than your PC.

I don't see a real problem with the PC being on the circuit when the brown-out happens. The worst case scenario is that the computer would turn off or reset. Is that happening?

FWIW, I've seen PCs stay on even when no power is available to it for a short amount of time... say less than a second. I've also seen a PC stay on for about 30 seconds without it being plugged in at all.

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In any case the (switching) power supply electronics WON'T be happy about voltage fluctuations :ph34r: and IF somehow there are fluctuations on the DC side also, electronics inside the PC and particularly the hard disk(s) won't be happy as well.

jaclaz

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One says its okay, one says it's not ... Which is it? I read elsewhere that "Since all computers are equipped with very good switch mode power supplies, these power supplies can easily compensate for a dip in the AC voltage. Therefore your computer won't be damaged."

It never turns off any equipment.

The voltage of the room is 118VAC and when I turned the Air on Cool mode it dipped to 110-114 then back to 116 and is currently at 115ish and hanging around there.

Edited by tal ormanda
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Unless you have an ups you shouldn't let the pc plugged on the same electric circuit. Also, there might be a bigger problem as the air con shouldn't make this kind of things if it were properly connected to an isolated electric circuit (that's a rule here in new buildings).

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tal ormanda ... About computer power supplies surviving mains sags ... You want to hear a definitive answer but I'm afraid there is not one definitive answer. Remember that even within the same model of something there is variation. Unfortunately there are many models of computer power supply so now we're talking massive variation. Add the variables from all the possible power companies and their wiring from them to you and we are approaching infinite variation. This is why it is NOT answerable.

Personally, I find modern power supplies ( 400W and up ) pretty tolerant on the primary side. They are designed for our shoddy mains with a wide range of voltage ( I think 100 to 130 ). And like someone else said above, often make it through noticeable sags ( not "brownouts" which are usually from external sources and last too long in time ). However, the fact that I find them excellent is a product of my specific environment.

In general, the problem is in the duration of the sag. Under a cycle ( here at 60 Hz less than a second ) everything UL listed should survive and many quality power supplies will surprisingly make over a second. The crappy things that always seem to have a blinking time display like Microwaves, Clocks, Coffee Makers, etc have tiny power supplies made by the lowest bidder and we should really call them ... sag flags. :lol:

Don't take this the wrong way but remember that whatever you read online might be interesting, it may even be correct, but it is not wise to place complete faith in it. So, if you have an abnormally long or deep sag from the air conditioner or refrigerator the electric motor or related circuits might be going bad ( pulling way too much inrush current ), or it might not! You will want to consult a licensed electrician for your area ( over here it is by county ) familiar with the local system to spot any defects. They will know the source ( your utility ) and its track record, they can glance at your power lines on the poles and tell if it is shoddy, and most importantly all around the house for anomalies. I know just enough to be considered dangerous but rely on several friends who are electricians to stay alive!

Sags are not unusual. We have a washer that always cause a short sag and a dryer that causes a very very short sag and they have been consistent for years. They are on their own separate circuits ( if they were on another with something else it would no doubt be worse ). When the motor starts to go south I should be able to tell by the difference in lights dimming and motor sound. Oh yeah, there is a groundwater sump pump that makes the biggest sag! Every.time.the.float.clicks.up.again.and.again.and.again. :realmad: So when we have these tropical storm and hurricane floods it goes like that for days every 10-15 minutes, on and off and on and. But the computers and stuff on different circuits sail right through it fine.

By all means use separate circuits ( not outlets, circuits ) if possible. NOTE: one possible exception is that using interconnected equipment on different circuits can create a ground loop or hum. If your mega-stereo and TV are on one circuit and the computers on another and you jack your nVidia mega-super-card to your Plasma TV, or your computer audio to your kilowatt stereo the potential for different grounds exists. They are even described as dangerous in some scenarios. I put all similar things one circuit to be safe. And ask my friends.

Slightly related: I once had a TV and Microwave on the same circuit as a computer and if a DVD was burning while the TV was on and you turned the Microwave on at the same time it caused a deep sag and then the circuit tripped off. I never really figured out why and just moved them to separate circuits and no longer have any of them. But it was probably the large inrush on a circuit already saturated ( probably 10A ) just pushing over the breaker. Just an inconvenience really, well, and a DVD coaster and 5-stage Chkdsk :lol: Yeah go for different circuits. And UPS if you can swing it because it will make most issues like this a moot point.

NOTE: circuits can and usually have multiple outlets. It pays to know which are which, at both ends. I prefer labels at the wall outlets and back at the breaker box.

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One says its okay, one says it's not ... Which is it? I read elsewhere that "Since all computers are equipped with very good switch mode power supplies, these power supplies can easily compensate for a dip in the AC voltage. Therefore your computer won't be damaged."

Then why you asked? :unsure:

It never turns off any equipment.

That's good. :)

The voltage of the room is 118VAC and when I turned the Air on Cool mode it dipped to 110-114 then back to 116 and is currently at 115ish and hanging around there.

Measured HOW exactly?

Oscilloscope, voltage recorder or multimeter?

jaclaz

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One says its okay, one says it's not ... Which is it? I read elsewhere that "Since all computers are equipped with very good switch mode power supplies, these power supplies can easily compensate for a dip in the AC voltage. Therefore your computer won't be damaged."

Then why you asked? :unsure:

It never turns off any equipment.

That's good. :)

The voltage of the room is 118VAC and when I turned the Air on Cool mode it dipped to 110-114 then back to 116 and is currently at 115ish and hanging around there.

Measured HOW exactly?

Oscilloscope, voltage recorder or multimeter?

jaclaz

Multimeter.

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Multimeter.

Well, then - no offence whatever intended :) - irrelevant data. :ph34r:

I presume that it is a digital multimeter.

Such an instrument has a "stabilizer" or if you prefer a "cache" or a "retarding circuit" to allow the LCD to display a number, what you read is actually an "average" over a (small, but not small enough) interval.

For all you know the drop could be (briefly) well below 100 volts.

Filming an analogic voltmeter would give you (at 30 frames per second) maybe half the precision needed to measure a drop voltage @60 Hz (you have to consider the hysteresys of the actual instrument), but in any case better than any common digital multimeter, which measures RMS:

http://www.newton.dep.anl.gov/askasci/eng99/eng99515.htm

Fluctuations in AC within 5% (which is what you described) should not produce "flicker", which should be noticeable when the fluctuation reaches (or nears) about 10%.

jaclaz

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Note that, at least here in the US, having specific outlets for appliances like microwaves and air conditioners (that draw a lot of initial power when they start) on a separate circuit (or circuits, depending on the # of outlets and other appliances in and out of the house supplied by the panel) is part of the building code nowadays. Moving appliances like this onto their own circuit is always a good idea, and getting an electrician to do it usually isn't that big a deal either, unless your power panel is already heavily subscribed ;). From what you describe, it sounds like there was a line run from the power panel specifically for that outlet, but it wasn't placed on a separate circuit (hence the separation might be at the breaker, but not at the circuit).

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Well I don't know then. There's no way to keep the room cool for the equipment.... What if I turn on AC before the computer? Or just get a UPS for the computer to maintain a steady voltage? What UPS to get?

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