Uninterruptable Power Supplies, Interrupted
January 16, 2018 6:56 AM Subscribe
None of our UPSes are currently preventing electronics from shutting down during blackouts. They are all either brand-new or were known to work properly (nothing would shut down during a short blackout) . Their loads are all under capacity and the batteries are all good. What's happening and how can we fix this?
The UPSes have plenty of headroom for the power draw of the devices that are always-on through them. All the UPSes are APC, mostly by coincidence. Almost all the batteries are less than two years old.
We've lived at a few different addresses in the same city over the past dozen years, and have had the same power utility for all of them (Duke Energy). Previous residences were in neighborhoods 10-15 years old. Our current house and neighborhood are about 30 years old. All our neighborhoods have had buried lines.
At our current house we've had occasional power fluctuations -- sometimes a couple incidents a week, sometimes less than once every two months -- that have the impact of short blackouts. Sometimes they happen while HVAC is running, sometimes not. They don't seem to be brownouts because the power cycles fully off when they happen. For example all the electronic displays on appliances are completely dark and are reset when power restores; houselights turn off completely rather than flicker, HVAC shuts off completely, etc. The power will be out for anywhere from a couple seconds to half a minute. A full-on blackout lasting over a minute has been rare enough to make it hard to say how frequently those occur.
What might be causing this and what can we do about it, short of radically re-engineering our role in the power grid? We are planning to add solar panels but it won't happen for at least a year due to budgets. We'd like to not lose computers and hard drives to the status quo before then.
A whole-house power management unit might solve the problem but it would be an unwelcome expense unless we know for a fact it will work and can be repurposed into any eventual solar system we install. Since none of our small, discrete UPSes can cope with the fluctuations, I'm currently skeptical that a large monolithic one can.
The UPSes have plenty of headroom for the power draw of the devices that are always-on through them. All the UPSes are APC, mostly by coincidence. Almost all the batteries are less than two years old.
We've lived at a few different addresses in the same city over the past dozen years, and have had the same power utility for all of them (Duke Energy). Previous residences were in neighborhoods 10-15 years old. Our current house and neighborhood are about 30 years old. All our neighborhoods have had buried lines.
At our current house we've had occasional power fluctuations -- sometimes a couple incidents a week, sometimes less than once every two months -- that have the impact of short blackouts. Sometimes they happen while HVAC is running, sometimes not. They don't seem to be brownouts because the power cycles fully off when they happen. For example all the electronic displays on appliances are completely dark and are reset when power restores; houselights turn off completely rather than flicker, HVAC shuts off completely, etc. The power will be out for anywhere from a couple seconds to half a minute. A full-on blackout lasting over a minute has been rare enough to make it hard to say how frequently those occur.
What might be causing this and what can we do about it, short of radically re-engineering our role in the power grid? We are planning to add solar panels but it won't happen for at least a year due to budgets. We'd like to not lose computers and hard drives to the status quo before then.
A whole-house power management unit might solve the problem but it would be an unwelcome expense unless we know for a fact it will work and can be repurposed into any eventual solar system we install. Since none of our small, discrete UPSes can cope with the fluctuations, I'm currently skeptical that a large monolithic one can.
Response by poster: > What model APC UPS's do you have? Are you sure things are plugged into the battery backup ports?
A variety; if it's very important I can take inventory later, but they're from various parts of APC's product range and they react to this problem uniformly.
I am absolutely 100% certain that everything requiring uninterruptable power is connected to the proper ports, because I compulsively check this after every failure.
posted by ardgedee at 7:18 AM on January 16, 2018
A variety; if it's very important I can take inventory later, but they're from various parts of APC's product range and they react to this problem uniformly.
I am absolutely 100% certain that everything requiring uninterruptable power is connected to the proper ports, because I compulsively check this after every failure.
posted by ardgedee at 7:18 AM on January 16, 2018
Assumption: you pull the plug and the load stays on, but in a blackout, the load is not maintained.
I guess the first step is to call APC. Hopefully, they will work with you, and not just say the units need repair.
Maybe the easiest solution is to buy 1 UPS of another brand and see if that acts the same.
The only cause I can think of is that you are getting a glitch of a certain frequency or duration that turns off the UPS.
I have had an APC unit for years and never had a problem.
posted by H21 at 7:18 AM on January 16, 2018 [1 favorite]
I guess the first step is to call APC. Hopefully, they will work with you, and not just say the units need repair.
Maybe the easiest solution is to buy 1 UPS of another brand and see if that acts the same.
The only cause I can think of is that you are getting a glitch of a certain frequency or duration that turns off the UPS.
I have had an APC unit for years and never had a problem.
posted by H21 at 7:18 AM on January 16, 2018 [1 favorite]
Response by poster: To reiterate: These units worked properly at a previous address, they do not work properly at this address.
My suspicion is that the UPS manufacturer is less relevant than the household power. Or, at least, the UPSes are a constant and the address is a variable strongly correlatable to the change in behavior. I would rather know what could be relevant to the change of address.
posted by ardgedee at 7:21 AM on January 16, 2018
My suspicion is that the UPS manufacturer is less relevant than the household power. Or, at least, the UPSes are a constant and the address is a variable strongly correlatable to the change in behavior. I would rather know what could be relevant to the change of address.
posted by ardgedee at 7:21 AM on January 16, 2018
What happens when you leave the UPS plugged in and flip the circuit breaker?
posted by mskyle at 7:22 AM on January 16, 2018
posted by mskyle at 7:22 AM on January 16, 2018
This doesn’t fully explain your problem, but I have had a lot of trouble with APC’s consumer UPSes in the last decade or so, including needing frequent (1-2 years) battery replacement and a tendency to drop power to the equipment when the battery is “bad” even though there is still AC power. I have had more hard shutdowns on my equipment due to APC UPS design flaws and quality problems than actual power outages in the past few years.
posted by musicinmybrain at 7:26 AM on January 16, 2018
posted by musicinmybrain at 7:26 AM on January 16, 2018
This doesn’t fully explain your problem, but I have had a lot of trouble with APC’s consumer UPSes in the last decade or so, including needing frequent (1-2 years) battery replacement and a tendency to drop power to the equipment when the battery is “bad” even though there is still AC power.
I've had similar experiences with APC gear shitting the bed in various ways. For my money, Tripp-Lite makes a really solid product.
Since none of our small, discrete UPSes can cope with the fluctuations, I'm currently skeptical that a large monolithic one can.
I suspect you're also having over-voltage and under-voltage events - and those play havoc with inexpensive UPSes. It tends to be hard on batteries if the electronics aren't up to the task of evening that noise out. Bigger UPSes have better electronics - they are less sensitive to price and complexity. A whole house setup might be overkill, and costly, but going with a better (more expensive) UPS at the point of consumption will yield better results.
Also, I'd have an electrician over to have a look at your wiring. I had some weird power issues at my house, and when the solar was installed they discovered that the lug holding the neutral was only finger tight. Since that got fixed (and the solar installed) I've had far fewer issues.
posted by Pogo_Fuzzybutt at 7:35 AM on January 16, 2018 [2 favorites]
I've had similar experiences with APC gear shitting the bed in various ways. For my money, Tripp-Lite makes a really solid product.
Since none of our small, discrete UPSes can cope with the fluctuations, I'm currently skeptical that a large monolithic one can.
I suspect you're also having over-voltage and under-voltage events - and those play havoc with inexpensive UPSes. It tends to be hard on batteries if the electronics aren't up to the task of evening that noise out. Bigger UPSes have better electronics - they are less sensitive to price and complexity. A whole house setup might be overkill, and costly, but going with a better (more expensive) UPS at the point of consumption will yield better results.
Also, I'd have an electrician over to have a look at your wiring. I had some weird power issues at my house, and when the solar was installed they discovered that the lug holding the neutral was only finger tight. Since that got fixed (and the solar installed) I've had far fewer issues.
posted by Pogo_Fuzzybutt at 7:35 AM on January 16, 2018 [2 favorites]
Part of the question is what sort of "electronics". Speaking from the computer-y/server-y realm, I can tell you that a cheap UPS, with problems described above by others, when combined with a power supply that is fairly taxed or maybe even in the early stages of failure, can cause the computer to reset.
It would be prudent to check your watts drawn by each device and compare it to the rating of the power supply inside the device. A PC that is eating 200 watts on a generic 300 watt PSU is cutting it kind-of close for being able to deal with brownouts or other line cruft, whereas a 550 watt PSU from a quality PSU company might not blink.
If you have low-end UPS devices, such as the APC Back-UPS line, this is definitely "a thing" because line cruft will often sail right through these devices. One step up would be a better quality UPS. Within the APC line, this would probably be the APC Smart-UPS SMT or SMX units, which are "line interactive" which means they will boost or drop voltages in an effort to provide cleaner power without dropping to battery. The best option from a power reliability angle is a double conversion UPS. This type of UPS converts power to DC battery voltage, and then from there to an inverter that creates clean AC power. These are nearly bulletproof, but they're pricey and they are not as efficient, because there are significant conversion losses converting AC->DC->AC. But that fixes nearly ANY power quality problem.
APC has had quality problems in the past, especially back in the '90's, when float voltages on the APC SmartUPS units tended to be off and this would lead to batteries cooking. I would be suspicious of their low-end products. They acquired another company for the technology behind some of their higher end UPS's like the SMT and SMX's, which I've been replacing on a 5(!) year cycle, because the charging circuit is really that much better.
posted by jgreco at 4:05 PM on January 16, 2018
It would be prudent to check your watts drawn by each device and compare it to the rating of the power supply inside the device. A PC that is eating 200 watts on a generic 300 watt PSU is cutting it kind-of close for being able to deal with brownouts or other line cruft, whereas a 550 watt PSU from a quality PSU company might not blink.
If you have low-end UPS devices, such as the APC Back-UPS line, this is definitely "a thing" because line cruft will often sail right through these devices. One step up would be a better quality UPS. Within the APC line, this would probably be the APC Smart-UPS SMT or SMX units, which are "line interactive" which means they will boost or drop voltages in an effort to provide cleaner power without dropping to battery. The best option from a power reliability angle is a double conversion UPS. This type of UPS converts power to DC battery voltage, and then from there to an inverter that creates clean AC power. These are nearly bulletproof, but they're pricey and they are not as efficient, because there are significant conversion losses converting AC->DC->AC. But that fixes nearly ANY power quality problem.
APC has had quality problems in the past, especially back in the '90's, when float voltages on the APC SmartUPS units tended to be off and this would lead to batteries cooking. I would be suspicious of their low-end products. They acquired another company for the technology behind some of their higher end UPS's like the SMT and SMX's, which I've been replacing on a 5(!) year cycle, because the charging circuit is really that much better.
posted by jgreco at 4:05 PM on January 16, 2018
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Potential issues i can think of:
APC's ups model lineup seems intentionally opaque, but a lot of the models won't raise or lower the voltage if it actually is a brownout, but they should switch to the battery, depending how low the voltage gets(automatic voltage regulation). Its possible they might need a large enough draw on one of the ports to know that something is connected, and a low draw device may not have enough to trigger the ups.
Active PFC on your computer: some ups's don't like the high efficiency power supplies, and the power waveform they generate isn't compatible. I don't know what the symptoms are, but you can read a little more about it at cyberpower: pfc-sinewave
(reading that page, cyberpower has "line interactive" ups's for reasonable amounts of money, apc wants way more - interactive should mean its always running through the battery + inverter so its never "switching" to battery when power goes out, its a quicker transition, now i need to look at cyberpower for my own usage).
edit: my mistake - i was thinking of double conversion for the always being used tech, not line interactive. Im not sure what they mean by line interactive.
posted by TheAdamist at 7:14 AM on January 16, 2018