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DamienChaos 10-12-2009 12:58 PM

Recurring Power Oddities - Regular Schedule
 
Hi all,
I've been troubleshooting something in my home for a while now, and am really at a loss as to where to go from here (except hire an electrician). I thought I'd post here just as a last-ditch effort.

When I moved into my home last year (rather new, built in 2006), I noticed that the Uninterrupted Power Supply for my computer switched to battery power for short spurts (5-10 seconds) occasionally. The software for the UPS states that a blackout was detected, although nothing else in the house seems to be negatively impacted. Even "sensitive" electronic equipment not connected to a UPS, like other computers and TVs, exhibit no issues.

The only other symptom I have noticed is that, at the same time the UPS switches to battery power, a faint and barely audible "buzzing" also occurs in any running ceiling fans throughout the house. This is the only other symptom than the UPS, and there's otherwise no negative impact to the fan (no flickering lights or reduction in fan speed).

Recently, I discovered that this oddity occurs daily at scheduled times. Particularly, at approximately 8:34pm. This allowed me to anticipate the odd event, unplug the UPS and observe that the buzzing in the ceiling fans is not sourced in the UPS (i.e. at 8:34pm, fans still buzz for 5-10 secs even with UPS not plugged into the wall).

I had the power company come check the power coming into the house and they didn't observe any issues (although they weren't there at 8:34pm). Nothing in the house runs on a timer except for the irrigation system, which is currently switched off. I've also determined that the problem is not sourced in the HVAC system, as the power oddity also occurs when the heat pump breaker is off.

Has anybody encountered anything like this before? I'd certainly welcome any ideas or thoughts on what the source could be or how to troubleshoot further. It wouldn't be such a weird thing if the odd power issue didn't happen at almost exactly the same time every day.

Appreciate any and all input!

--DC

Yoyizit 10-12-2009 02:16 PM

Quote:

Originally Posted by DamienChaos (Post 339631)
Appreciate any and all input!

--DC

I think a piece of PoCo's equipment is failing gracefully. Ask your neighbors if they have problems like this.

They will be furious, but get your PoCo to hook up a recording voltmeter to your line. Also, a recording frequency meter [the buzzing in the fans] wouldn't be a bad idea. Tell them if they want to save money they should come in the evening.

One outcome to this exercise is that they will deny that they found anything but the problem will disappear.

You can also check your entire house elec. system with a voltmeter, hair dryer and elec. wall oven. I'll look for the recipe for this but I'd look to PoCo first.

What do your incandescents do at 8:34?

DamienChaos 10-12-2009 02:22 PM

I can definitely talk with the power company about putting a volt and/or freq meter on the line. Odds are they will do some major complaining, but will see what I can get.

That recipe for testing the house with a voltmeter sounds promising as well.

Not too many incandescent bulbs left in the house, but I don't believe the few I do have show no ill effects. Let me test that this evening to be 100% sure and I'll report back. I do know that the "buzz" comes from the fan, as if the bulbs are off the sound is heard.

Thanks for the help!

Yoyizit 10-12-2009 02:44 PM

Quote:

Originally Posted by DamienChaos (Post 339693)
That recipe for testing the house with a voltmeter sounds promising as well.

Try one of these
http://images.google.com/imgres?imgu...a%3DN%26um%3D1
at 8:34.

The cheaper the meter, the shorter the needle, the less the meter movement is damped, the more responsive it is to freq. and voltage variations.
Digital meters using sampling may not show anything.

BTW, people in the US don't seem to use the phrase "as well" as you have used it. I'd say you were from England.

DamienChaos 10-12-2009 03:03 PM

Thanks again...the voltmeter should provide significantly more info than I have right now. The UPS software just tells me that I'm having a blackout, which is obviously not the case.

Not from England, but I do advise client contacts globally, particularly in the UK. Looks like their conversational accent may have worn off on me. Hopefully I won't start using words like "posthaste"!

Again, much appreciate the input!

AllanJ 10-12-2009 04:30 PM

If these "events" last for five seconds and there is a voltage change of more than say three volts, then an ordinary voltmeter of your own will show them.

Maybe a neighbor is drawing a lot of power at those moments.

If your UPS is calibrated so its sensing of blackout is just a few volts less than the usual voltage for your house and street then the UPS may trip before you notice any lights dimming.

CDH 10-12-2009 09:18 PM

Quote:

Originally Posted by Yoyizit (Post 339692)
I think a piece of PoCo's equipment is failing gracefully. Ask your neighbors if they have problems like this.

They will be furious, but get your PoCo to hook up a recording voltmeter to your line. Also, a recording frequency meter [the buzzing in the fans] wouldn't be a bad idea. Tell them if they want to save money they should come in the evening.

One outcome to this exercise is that they will deny that they found anything but the problem will disappear.

You can also check your entire house elec. system with a voltmeter, hair dryer and elec. wall oven. I'll look for the recipe for this but I'd look to PoCo first.

What do your incandescents do at 8:34?

Failing poco equipment generally does'nt fail on a schedule ie. everynight at 8.34pm, as far as the poco being upset they should'nt be, this day and age most poco's have what they call power quality which is where they come out and install a voltage recorder on your metercan as stated earlier. I have been to hundreds of lights flickering, partial power etc calls and the first thing I always do is change the connectors at the weatherhead and the pole, whether I find a problem or not as it can't hurt, but I have never been to one with a problem like your's, I am betting it is something on your side.

spark plug 10-12-2009 09:49 PM

Quote:

Originally Posted by AllanJ (Post 339751)
If these "events" last for five seconds and there is a voltage change of more than say three volts, then an ordinary voltmeter of your own will show them.

Maybe a neighbor is drawing a lot of power at those moments.

If your UPS is calibrated so its sensing of blackout is just a few volts less than the usual voltage for your house and street then the UPS may trip before you notice any lights dimming.

I tend to agree with AllanJ. The most likely cause is that someone else who is on the same Transformer is drawing an extra heavy load at that time. I also remember installing (myself being the Junior, Junior member of the crew) a Multi-Horsepower Motor in a new, Industrial building, with a Manual starter, and a neighboring shop was having power problems. Also, as an indicator of a "SAG" in the supply of power, see if the digital clocks on stoves or alarm clocks are blinking. (No matter what) Don't Drink and Drive, Ever!!!

DamienChaos 10-13-2009 07:11 AM

Thanks again to all for the input. Incandescent lights don't exhibit any sort of issue when the power fluctuation occurs...at this point it's still just the same two symptoms. Nothing else (even an older, less sophisticated UPS) has any issues. Plenty of digital clocks in the house and the issue has never caused any of them to start blinking.

I'm going to see if I can grab a voltmeter and investigate to see what's happening on my side. It could be a neighbor, but I'm not sure who might be pulling that much power. None of my neighbors has a wood shop, compressor, welding apparatus, or anything like that.

Who knows, maybe it's just the power company sending some sort of signal down the line to check the meter. If nothing else, the voltmeter will settle my concerns as to whether the power fluctuation is enough to be harmful.

Again, can't thank you all enough for the input!

Yoyizit 10-13-2009 12:03 PM

Quote:

Originally Posted by DamienChaos (Post 340036)
Incandescent lights don't exhibit any sort of issue when the power fluctuation occurs...at this point it's still just the same two symptoms.

I can't imagine what this could be, unless the UPS has an internal clock or something that counts up and it is causing the fan problem.

WFO 10-17-2009 09:11 PM

Quote:

Originally Posted by Yoyizit (Post 339692)
They will be furious, but get your PoCo to hook up a recording voltmeter to your line. Also, a recording frequency meter [the buzzing in the fans] wouldn't be a bad idea. Tell them if they want to save money they should come in the evening.

One outcome to this exercise is that they will deny that they found anything but the problem will disappear.

This kind of remark always amazes me. Our Coop installs recording voltmeters on a regular basis, at no cost, and consider it a part of providing service. If a problem is found, we deal with it and let the customer know. If your POCO is not like this, you have my sympathy. Maybe Coops are different than what you have to deal with, but don't tar everyone with the same brush.

As for whether it may be the POCO's problem, the only thing I can think of that would be regularly switched at a given time would be a capacitor bank. Time/temperature controls are quite common and this could definitely have an effect on voltage. They (the POCO) should be able to answer this question as well.

Yoyizit 10-18-2009 09:48 AM

Quote:

Originally Posted by WFO (Post 342112)
This kind of remark always amazes me. Our Coop installs recording voltmeters on a regular basis, at no cost, and consider it a part of providing service. If a problem is found, we deal with it and let the customer know. If your POCO is not like this, you have my sympathy. Maybe Coops are different than what you have to deal with, but don't tar everyone with the same brush.

In my area, the PoCo, GaCo and TelCo have, at one time or another, acted like Tony Soprano, maybe because no one can/will stop them. And now the WaCo has water mains breaking in a very public fashion, apparently because the money that was to go to maintaining infrastructure went somewhere else.

AllanJ 10-19-2009 08:24 AM

>>> frequency meter

I don't think it is technically possible to have a sudden frequency change in an electrical power system.

Nowadays large regions (multiple states if not the entire country) are all interconnected as "the grid" and every generator has to be in step (in phase) with the rest of them.

If a generator strayed off frequency, the power it delivers compared with the power already in the grid would look like a short circuit and a breaker should trip.

>>> sending some kind of signal

Yes, this could be the case, for the purpose of among other things switching some customers' services from on peak to off peak billing using separate meters at each customer's location. This would consist of an AC current probably of some multiple of 60 (Hz) injected into the power lines and arriving superimposed on the regular 60 Hz power.

This signal is not going to be large; the power company isn't going to have a big generator on hand to create that signal. Also it must not add significantly to the net (or measured or nominal) voltage.

tripflex 10-19-2009 12:57 PM

Plug a light into that outlet and see if at 8:34 or whenever, if the light flickers, or turns off.

CDH 10-19-2009 08:38 PM

By no means is the original posters UPS the most sensitive piece of equipment on the feeder or circuit that he feeds off of, there are alarms on chillers and all kind of other equipment that if this was happening on the whole feeder or system wide the power company would be bombarded by calls, not to mention power company's monitor their systems from power plants and their control center 24 hrs a day 7 days a week 365 days a year, that is transmission and distribution, as far as capacitor banks go if they are controlled by SCADA ie can be turned on/off remotely not manually they are generally not associated with a timer, it is generally more of a system need ie not happening everyday at 8.34. I have seen regulators get hung up with it raised several steps and as the demand eases at night it did'nt step down and alarms started going off, we went out found it and corrected it, point being these system wide problems are located pretty quickly and corrected, I still believe the OP has a problem albeit minor maybe it is with his UPS.


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