Windows 7 shutdown during power failure.


G

Gene E. Bloch

As a matter of fact, the Belkin UPS system I use will start talking to you
about you had so many minutes to close things down before it issued the
command to shut the main computer down itself before it lost power on the
battery backup.
It was like I was on the Starship Enterprise as it went into its countdown.
It can also send emails about its status too with software to give you a
complete status in real-time as to what was happening with the UPS and the
power it was providing.
Man, I ran my firewall appliance, wifi AP, printers, print server, computers,
floor stand lamps and anything else through that UPS in the so called
computer room/guest bedroom. :)
I have to ask - is there a USB link to your floor lamp to trigger a
clean shutdown?

OK, I'm just amusing myself, and with any luck, you too :)
 
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G

Gene E. Bloch

The computer runs off power from the wall plug - routed through the BPS for
the AVR and sensing for alarms - until there is a power failure. Then the
unit switches ALMOST instantly (those few milliseconds) to battery power and
keeps running. But I can't stop worrying about those milliseconds.
My take on that issue is this:

Everything in the computer is running from the computer's AC to DC
supply, and every one of the DC busses in that supply has filter
capacitors. These will provide current to their loads for enough
milliseconds that the short interruption of the UPS's output will not
matter.

Consider that in the old days before switching supplies, the filters
were reducing ripple due to the 120 Hz output of full wave bridge
rectifiers (it was a bunch of positive half cycles), hence they had to
maintain their output voltage and current for ~8 msec.

I have not addressed the possibility that real voltage spikes can get
through, because I'm not qualified to talk about that.
 
R

ray

You *can*, but unless you have a very powerful, expensive USP, it's not
a good idea at all. With several computers connected to one UPS, that
UPS doesn't have enough power to keep the computers running for more
than a couple of minutes if the power goes off. You want to have enough
time to notice what happened, get to the computers and power each one
off in orderly fashion, and you may not have enough time.

I have three desktops here, kept powered on all the time. Each of them
has its own inexpensive APC UPS.
A factor will be what sort of outages you experience. Most of the ones I
see are a few seconds. On those occasions we've had longer ones and the
UPS has ultimately run down, I've had no problems - simply reboot.
 
S

Satanic Mechanic ©

On 2/6/2012 8:23 AM, Satanic Mechanic © wrote:

<snipped>
<yawn>

You really are a clown. And technically you are some kind of a deranged
loon. You are doing nothing but babbling here, which I could care less
about your babble, and you are in lunatic heat with a wild hair up your
John Brown behind parts for the sake of having a wild hair up your John
Brown behind parts.
i chuckle to myself and the voices in my head chuckle back. of course
you care about my babbling. if you didnt, you would not respond with
such crazy talk. me tinks im getting under your skin. do you see
anyone else breaking my testicles? only you are because you refuse to
take your meds as the dr dx'd.
ok sorry folks for the interuption of this nice little group. i will
not respond to tiny aluminum anymore.
 
B

Big Steel

On 2/6/2012 5:12 PM, Satanic Mechanic © wrote:

<snipped>
<yawn>
<not read>

Stop bothering me you rode in sitting high in the saddle on your satanic
donkey named Lucifer with you acting like the Satanic Lone Range with
you are right and everyone else is wrong nonsense.

<pfft>

<SLAPPED>

get lost...
 
B

Big Steel

I have to ask - is there a USB link to your floor lamp to trigger a
clean shutdown?

OK, I'm just amusing myself, and with any luck, you too :)
What? Just plugging the lamps into a surge protect strip along with some
other stuff was good as gold with those 6ft torch style floor lamps.
Even the portable TV was powered via the UPS in the computer/guest bedroom.
 
G

Gene E. Bloch

What? Just plugging the lamps into a surge protect strip along with some
other stuff was good as gold with those 6ft torch style floor lamps. Even the
portable TV was powered via the UPS in the computer/guest bedroom.
Actually my comment was meant as humor. I tend towards surrealism and
incongruity.
 
C

Char Jackson

Actually my comment was meant as humor. I tend towards surrealism and
incongruity.
And the occasional bad pun. Don't forget those. ;-)
 
P

Paul

Gene said:
My take on that issue is this:

Everything in the computer is running from the computer's AC to DC
supply, and every one of the DC busses in that supply has filter
capacitors. These will provide current to their loads for enough
milliseconds that the short interruption of the UPS's output will not
matter.

Consider that in the old days before switching supplies, the filters
were reducing ripple due to the 120 Hz output of full wave bridge
rectifiers (it was a bunch of positive half cycles), hence they had to
maintain their output voltage and current for ~8 msec.

I have not addressed the possibility that real voltage spikes can get
through, because I'm not qualified to talk about that.
Switching supplies, like the ATX power supply, are resilient to voltage
value. The incoming AC is converted to high voltage DC (by rectification).
And a switching converter can work over a wide range of DC values. The
only limits on wide range input, are the resulting levels of current
draw. (If the supply draws 300VDC at 1 amp, if the high voltage DC
drops to 100V, then the current draw would be 3 amps to support the
output power. And at some point, the switching transistors will be
exceeding the current they can safely handle. That's why they have
to stop a switching converter, from trying to run when the input
voltage is too low. It would do it, if you let it.)

The ATX supply has a minimum of around 16 milliseconds of holdup time
at full load. This is guaranteed by the input capacitor (the one on the
high voltage DC side). If the ATX supply is not providing full load output
at the time of the AC failure, the power can last a lot longer. On my
current supply, if the computer is sleeping, the +5VSB can "stay up" for
30 seconds, using nothing but the input capacitor as an energy source.
That's without a UPS to help it. But at full load (which my computer
never draws), the supply can only maintain the output for 16 milliseconds.
(Check the spec sheet, as the value can be slightly longer than that.)
The 16 milliseconds of holdup, is enough holdup to support the usage
of a cheap UPS. The UPS transfer time, will be a number less than that.

The original ATX supplies were also waveform tolerant. That's because the
input stage (where cord enters the box) doesn't use a transformer, so
there are no harmonics to worry about. So if the waveform wasn't a
perfect sine wave, the old supplies didn't mind.

That changed, with the advent of ATX supplies featuring either passive
or active PFC (power factor correction). An Active PFC has an expectation
about the wave shape. It tries to make a sinusoidal input current, based
on monitoring the input AC voltage and assuming the voltage waveform
is also a sinusoid. (In other words, it uses the AC voltage as a
template for its behavior.) If a UPS with square wave output is
connected to an Active PFC ATX supply, then a less than ideal behavior
results. The extent to which this is an issue, will depend on
whether the idiot designing those chips, considered cheap UPS
boxes as a potential power source :-(

So in fact, a "true sine wave" UPS (the more expensive kind), is
ready for any kind of computer ATX power supply you throw at it.
Whereas a square wave UPS (or modified sine UPS), those would
work best with a non-PFC ATX supply. This is one reason, the last
two power supplies I bought, I was careful to make sure they had
no power factor correction, as then, they would not be affected
by my crappy UPS (which does what is needed, just fine).

The transfer time of a UPS, can range from zero to one would presume,
close to 16 milliseconds. A UPS would be pretty useless, if every
ATX supply connected to it, "tipped over", so the switching
interval must be shorter than that. A UPS with a zero transfer time,
costs more than one with finite transfer time. My UPS is not zero
transfer time, and the output is probably modified sine wave, rather
than being so horrible as to be pure square.

A double conversion UPS, has a zero transfer time, because it
never transfers anything :) You can tell you've got a double
conversion one, because of the loud fan that runs all the time,
the humming and the heat. (We had one at work.) The unit is
basically doing its own power conversion at all times. My UPS,
by comparison, does jack squat 99.999% of the time (bypass mode),
and makes an ugly noise when the AC goes off. And to some extent,
that contributes to its long life (runs ice cold, and will most
likely die of battery failure).

[ Everything in life has tradeoffs ]

Paul
 
K

Ken Blake

Hi, Ken.

While I don't disagree with you, there is an important point that is being
overlooked in this discussion: switching time.

You are right of course. That's an important point, but it's not what
we were talking about. My comment was simply in response to Paul's
posting that "If you don't want or need the warning feature, you can
certainly run multiple PCs from one UPS. That works fine." I don't
disagree with what he said, but I wanted to point out that you could
only do that with a very expensive UPS, and my preference is to have
less expensive separate UPSs for each computer.
 
K

Ken Blake

A factor will be what sort of outages you experience. Most of the ones I
see are a few seconds. On those occasions we've had longer ones and the
UPS has ultimately run down, I've had no problems - simply reboot.

Yes, "simply reboot" often works fine. However when you don't have an
orderly shutdown, as you wouldn't if the UPS ran down, you run the
great risk that the disorderly power off can create all sorts of
problems.
 
R

Roy Smith

Just today we have suffered two utility power failures, all without
any warning!
Really?!? When was the last time the power company ever notified anyone
of a power failure? ;-)
Is there some device to put between the computer and the wall socket,
in conjunction with Windows7, to initiate a normal computer shutdown
when the power fails?
Sure it's called a UPS or Uninterrupted Power Supply. Basically what it
is is a box with a rechargeable battery inside. A circuit monitors the
battery and recharges it when needed, it also monitors the power from
the wall socket. When the AC power from your wall socket fails, it
instantly switches to the (electronically generated) AC power from the
battery. A UPS devices can provide anywhere from 5 to 15 minutes (or
more) of power so that you can save your work and shut down your PC safely.


--

Roy Smith
Windows 7 Home Premium 64-Bit
Thunderbird 10.0
Monday, February 06, 2012 8:44:09 PM
 
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I

Ian Jackson

Satanic said:
this is exactly wtf i am talking about. he couldnt google UPS or even
take a walk in his local computer store and get advice there.
btw a UPS will not initiate a normal shutdown as you sit there with
a brewski and wait for the power to come on. A UPS will give you a
few minutes of power so YOU can shut you pc down. technically your
answer is incorrect
Some UPSes do indeed initiate a controlled shut-down when the mains
fails.

Well, at least they used to. 15 years ago, some of the professional
equipment I worked with certainly did. Of course, you have to make sure
that the battery doesn't go flat while the computer is shutting down. If
there have been several shutdowns in quick succession, it is wise to let
the battery charge for a while before re-starting the computer.
 

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