Just an inquisitive question. My UPS seemed to go mental last night/this morning (around midnight Sat Oct 1st) flicking between battery and mains repeatedly for a few hours.. But no flickering lights or anything.. Im wondering if anyone else had something similar? Im assuming it may have been the power company doing something weird re: daylight savings? Kyle Carter
Hello, As an electrical engineer with 10 years experience working in electricity distribution systems, I doubt very much it would have anything to do with the lines company signalling system ie the system used to turn streetlights off and on and control electric hot water systems during peak demand periods. You would have experienced problems much sooner as the signalling systems are used everyday. However, it is quite possible that your ups might be reacting to others electrical equipment off the same supply (same (22k/11k/400/240VAC) transformer or that they might be problems with your electrical supply ie broken neutral etc. Do you have any AC power clocks? They are very sensitive to power quality issues because they take their timing from the 50Hz 240AC waveform. Or a fax machine? They often have a feature for reporting electrical disturbances. Unless you can record a power quality or disturbance issue, I would suspect the problem is with the UPS. Good luck, On Sunday 02 October 2005 23:01, Kyle Carter wrote:
Just an inquisitive question. My UPS seemed to go mental last night/this morning (around midnight Sat Oct 1st) flicking between battery and mains repeatedly for a few hours.. But no flickering lights or anything..
Im wondering if anyone else had something similar? Im assuming it may have been the power company doing something weird re: daylight savings?
Kyle Carter
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As a tech using a lot of mains sensitive equipment with about 25 years of suffering the bad power in NZ I would suggest that if the ups is fine today you have 2 options 1. Brown out - Very good chance on this, the average UPS switches fast to avoid letting the power fall to low, so if the NZ supply, usually 240V falls to say 200-210 ( supply company doing line maintenance and running on a temp (not very stable ) supply arrangement) your lights will be fine, most equipment will work fine ( but you toaster will take longer to make toast) and the ups will try to switch to battery. if you are right on the ups switching threshold ..... lots of clicking. 2. the ups batteries could be suspect. I assume you test them occasionally ?? Its amazing how many problems a tired cell in a battery causes a ups. On the aside, I looked at our data from last night and we didn't see anything north of Hamilton. so its at most a local thing. daylight saving was 2am, so it shouldn't be involved, I go for early morning hot wire line maintenance as a rough guess. WEL seem to like to do a lot at night nowadays On 3/10/2005, at 8:55 AM, Chris O'Halloran wrote:
Hello,
As an electrical engineer with 10 years experience working in electricity distribution systems, I doubt very much it would have anything to do with the lines company signalling system
Unless you can record a power quality or disturbance issue, I would suspect the problem is with the UPS.
Good luck,
On Sunday 02 October 2005 23:01, Kyle Carter wrote:
Just an inquisitive question. My UPS seemed to go mental last night/this morning (around midnight Sat Oct 1st) flicking between battery and mains repeatedly for a few hours.. But no flickering lights or anything..
Im wondering if anyone else had something similar? Im assuming it may have been the power company doing something weird re: daylight savings?
Kyle Carter
2. the ups batteries could be suspect. I assume you test them occasionally ?? Its amazing how many problems a tired cell in a battery causes a ups.
From my experience most UPS batteries last about 2-4 years if they are lead acid - similar life expectancy to your cary battery which uses the same technology.
Ian
Gavin makes a good point in that it might have been an abnormal 11/22kV switching scenario which has resulted in a lower fault level locally. For this period, voltage fluctuations on the network might have been greater than usual when motors were started etc. Is there a sewage or water pumping station near? A factory? As Gavin pointed out, the voltage only has to drop below the threshold of the UPS before the UPS will kick in. And this may not have been noticeable in your household lights. My original reply was more discounting the idea that the signals power companies use to switch streetlights, hot water cylinders, tariff meters etc were affecting your UPS. These are typically in the order of 2-6% (200-400Hz, older systems 1500Hz) and generally not noticed. Happy to be proved wrong. If your UPS checks out fine and the batteries are okay, then your UPS was doing its job. The power networks aren't perfect and do need maintenance from time to time so it warrants protecting your computers etc. On Monday 03 October 2005 09:07, Gavin Denby wrote:
As a tech using a lot of mains sensitive equipment with about 25 years of suffering the bad power in NZ I would suggest that if the ups is fine today you have 2 options
1. Brown out - Very good chance on this, the average UPS switches fast to avoid letting the power fall to low, so if the NZ supply, usually 240V falls to say 200-210 ( supply company doing line maintenance and running on a temp (not very stable ) supply arrangement) your lights will be fine, most equipment will work fine ( but you toaster will take longer to make toast) and the ups will try to switch to battery. if you are right on the ups switching threshold ..... lots of clicking.
2. the ups batteries could be suspect. I assume you test them occasionally ?? Its amazing how many problems a tired cell in a battery causes a ups.
On the aside, I looked at our data from last night and we didn't see anything north of Hamilton. so its at most a local thing.
daylight saving was 2am, so it shouldn't be involved, I go for early morning hot wire line maintenance as a rough guess. WEL seem to like to do a lot at night nowadays
On 3/10/2005, at 8:55 AM, Chris O'Halloran wrote:
Hello,
As an electrical engineer with 10 years experience working in electricity distribution systems, I doubt very much it would have anything to do with the lines company signalling system
Unless you can record a power quality or disturbance issue, I would suspect the problem is with the UPS.
Good luck,
On Sunday 02 October 2005 23:01, Kyle Carter wrote:
Just an inquisitive question. My UPS seemed to go mental last night/this morning (around midnight Sat Oct 1st) flicking between battery and mains repeatedly for a few hours.. But no flickering lights or anything..
Im wondering if anyone else had something similar? Im assuming it may have been the power company doing something weird re: daylight savings?
Kyle Carter
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Yes, I was guessing a brownout, however didn't notice any other problems on the non-UPS systems.. Was just wondering if anyone else had noticed something or if it was localised to my area. (seems to be localised) To answer Lindsays question the UPS was flicking on and off constantly.. Around once a second for about 5 minutes. The UPS tests fine and didn't fault at all.. It just kept cycling between battery and line supply. My flatmate has mentioned something in my computer room beeping previously.. Which must be a similar issue .. Maybe the UPS must be fairly sensative to voltage changes (hardly ever tripped at my last house, but this house trips a bit more often) And yes, I know about power networks, im currently based and Huntly Power station, now that is some impressive machinery. -----Original Message----- From: Chris O'Halloran [mailto:chris.ohalloran(a)maxnet.co.nz] Sent: Monday, 3 October 2005 5:38 p.m. To: wlug(a)list.waikato.ac.nz Subject: Re: [wlug] Weird power Gavin makes a good point in that it might have been an abnormal 11/22kV switching scenario which has resulted in a lower fault level locally. For this period, voltage fluctuations on the network might have been greater than usual when motors were started etc. Is there a sewage or water pumping station near? A factory? As Gavin pointed out, the voltage only has to drop below the threshold of the UPS before the UPS will kick in. And this may not have been noticeable in your household lights. My original reply was more discounting the idea that the signals power companies use to switch streetlights, hot water cylinders, tariff meters etc were affecting your UPS. These are typically in the order of 2-6% (200-400Hz, older systems 1500Hz) and generally not noticed. Happy to be proved wrong. If your UPS checks out fine and the batteries are okay, then your UPS was doing its job. The power networks aren't perfect and do need maintenance from time to time so it warrants protecting your computers etc.
Every second for 5 minutes! Hmm, struggling to think of a disturbance scenario that would last for 5 minutes. To me that rules out motor starting. injection signals from power company equipment. voltage depressions caused by short circuit faults on other circuits. and Gavin doesn't report that there were frequency excursions. Curious, if you're sure the supply is free of harmonics, it's got me wondering about self healing insulations faults. Was it wet on the night in question? Cracked insulators or XLPE cable can exhibit self healing behaviour ie the partial fault current arc dries out the arc path improving its resistance or the arc energy melts the XLPE void and restores the insultion property. Well, must get back to work. Chris On Wednesday 05 October 2005 22:40, Kyle Carter wrote:
Yes, I was guessing a brownout, however didn't notice any other problems on the non-UPS systems.. Was just wondering if anyone else had noticed something or if it was localised to my area. (seems to be localised)
To answer Lindsays question the UPS was flicking on and off constantly.. Around once a second for about 5 minutes. The UPS tests fine and didn't fault at all.. It just kept cycling between battery and line supply.
My flatmate has mentioned something in my computer room beeping previously.. Which must be a similar issue .. Maybe the UPS must be fairly sensative to voltage changes (hardly ever tripped at my last house, but this house trips a bit more often)
And yes, I know about power networks, im currently based and Huntly Power station, now that is some impressive machinery.
-----Original Message----- From: Chris O'Halloran [mailto:chris.ohalloran(a)maxnet.co.nz] Sent: Monday, 3 October 2005 5:38 p.m. To: wlug(a)list.waikato.ac.nz Subject: Re: [wlug] Weird power
Gavin makes a good point in that it might have been an abnormal 11/22kV switching scenario which has resulted in a lower fault level locally. For this period, voltage fluctuations on the network might have been greater than usual when motors were started etc. Is there a sewage or water pumping station near? A factory?
As Gavin pointed out, the voltage only has to drop below the threshold of the UPS before the UPS will kick in. And this may not have been noticeable in your household lights.
My original reply was more discounting the idea that the signals power companies use to switch streetlights, hot water cylinders, tariff meters etc were affecting your UPS. These are typically in the order of 2-6% (200-400Hz, older systems 1500Hz) and generally not noticed. Happy to be proved wrong.
If your UPS checks out fine and the batteries are okay, then your UPS was doing its job. The power networks aren't perfect and do need maintenance from time to time so it warrants protecting your computers etc.
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On Fri, 2005-10-07 at 11:35 +1300, Chris O'Halloran wrote:
Every second for 5 minutes! Hmm, struggling to think of a disturbance scenario that would last for 5 minutes.
To me that rules out motor starting. Unless it's a sewerage pumping station working overtime to keep up with
The fact that it's isolated to this particular time frame has got me thinking. Weatherwise, it did pour down at this particular time... http://gamma.wired.net.nz/wx200/Week.html#Rate_Week the extra amount of water overflowing into the sewerage. (Please note overflowing - I'm not making a statement that storm water goes into the sewerage system because it doesn't.)
injection signals from power company equipment. voltage depressions caused by short circuit faults on other circuits. and Gavin doesn't report that there were frequency excursions.
Curious, if you're sure the supply is free of harmonics, it's got me wondering about self healing insulations faults. Was it wet on the night in question? Cracked insulators or XLPE cable can exhibit self healing behaviour ie the partial fault current arc dries out the arc path improving its resistance or the arc energy melts the XLPE void and restores the insultion property.
Yeah... :) More than likely... :) Now, how old is your house Kyle ? :) Any roof leaks ? :) Did this happen again on Tuesday and Wednesday night ?
Well, must get back to work.
Nah, it's Friday... Time for a beer...:)
Chris
UPSes also switch over from mains supply to battery when the mains frequency alters either way from 50Hz, and depending on whether the UPS is an online or standby unit well depend on it's tolerance to frequency excursions. Standby units are not very tolerant. Apart from the fact that the mains frequency can typically drop to 49.5 Hz and go up to 50.5 Hz, other factors include ripple control, for controlling things like Controlled Loads (Water Heating), Day/Night Tariff control (Night Store Heating), Street lights, which is basically done by injecting another frequency in the mains supply to cause the ripple relays to change over and that typically happens around this time. How often was the UPS changing over ? On Sun, 2005-10-02 at 23:01 +1300, Kyle Carter wrote:
Just an inquisitive question. My UPS seemed to go mental last night/this morning (around midnight Sat Oct 1st) flicking between battery and mains repeatedly for a few hours.. But no flickering lights or anything..
Im wondering if anyone else had something similar? Im assuming it may have been the power company doing something weird re: daylight savings?
Kyle Carter
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Kyle Carter wrote:
Just an inquisitive question. My UPS seemed to go mental last night/this morning (around midnight Sat Oct 1st) flicking between battery and mains repeatedly for a few hours.. But no flickering lights or anything..
Im wondering if anyone else had something similar? Im assuming it may have been the power company doing something weird re: daylight savings?
Kyle Carter
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Assuming the UPS or batteries are not at fault then a loose wire in the power network will do that, certainly if there is a breeze. Had the same problem turned out the pole connection was loose. Took allot of convincing to get the fault fixed as well as it was not effecting the lights etc. See if it does the same thing next time you have some wind.
DrWho? wrote:
Just an inquisitive question. My UPS seemed to go mental last night/this morning (around midnight Sat Oct 1st) flicking between battery and mains repeatedly for a few hours.. But no flickering lights or anything..
Im wondering if anyone else had something similar? Im assuming it may have been the power company doing something weird re: daylight savings?
Assuming the UPS or batteries are not at fault then a loose wire in the power network will do that, certainly if there is a breeze.
Had the same problem turned out the pole connection was loose. Took allot of convincing to get the fault fixed as well as it was not effecting the lights etc.
See if it does the same thing next time you have some wind.
After 20 years of being in the electrical industry myself, I would be more inclined to go with Gavin's and Chris's views, even though I mentioned the ripple control system. (I have heard UPSes react to the ripple control signal - but not for two hours). I have graphed a couple of UPSes around the University Campus and seen the mains frequency jump around between 49.5 and 50.5 Hz at this time of the night which is why I brought up frequency excursions, but this time of the day is a very popular time for WEL to do Network Maintainence on the 11/33KV lines. With the 230/400V incoming supply, typically it is noticable with lights dimming, etc, especially when you turn on large loads such as your oven. Loose neutral wire is a bit more of a gotcha, but with heavy loads, it's pretty obvious (that is why I mentioned the lights dimming when the oven is turned on). Also it wasn't windy on Saturday night, I just checked my weather station graphs. It sounds to me like it was a one off incident which went away after two hours, which is why I haven't considered the mains to the house or the UPS itself. Kyle, if it happens again, then let us know.
participants (8)
-
Chris O'Halloran -
Craig Box -
DrWho? -
Gavin Denby -
Ian McDonald -
Kyle Carter -
Lindsay Druett -
Lindsay Druett