power supply

[Not so quick]

Will getting an uninterruptible power supply
help keep my computer from crashing from
spikes and other power irregularities?

 

[Mike Walsh]

Yes. All UPS boxes have built in surge suppressors to reduce voltage spikes. A good one will also correct voltages sags and surges.

 

[Not so quick]

Yes. All UPS boxes have built in surge suppressors to reduce voltage

spikes. A good one will also correct voltages sags and surges.
Thanks Mike. How do I find out if it covers sags and
surges?

 

[w_tom]

Five basic power problems. Noise, harmonics, brownouts,
blackouts, and surges. The plug-in UPS protects from data
loss due to brownouts and blackouts. Noise and harmonic
problems are solved inside the computer. Plug-in UPS does
claim to protect from one type of spike - the type that
typically does not exist. Things they forget to mention.

Blackouts and brownouts do not damage properly constructed
hardware. A typically destructive transient will damage
hardware. That plug-in UPS does not even claim to protect
from that type of transient. They are devious. It claims
transient protection. Which type of spike? Since they don't
mention that part, then many 'assume' it protects from all
types of spikes.

Effective protection from destructive spikes is essentially
same concept demonstrated by Franklin in 1752 and installed in
virtually every town where damage is not an option. Such
protection is introduced in a previous discussion starting
with " RJ-11 line protection?" on 31 Dec 2003 in
pdx.computing, or
http://tinyurl.com/2hl53

BTW, don't forget to view those pictures of utility service
in FL; part of your computer's primary protection system.

Destructive spikes don't just crash a machine. They create
hardware damage. And computer power supplies are so resilient
that many other appliances would suffer before the computer.
For example Intel specs for ATX power supplies demand that
those supplies withstand transients of 1000 volts. Just
another fact that the plug-in UPS manufacturer forgets to
mention.

The plug-in UPS connects a computer directly to AC mains
when not in battery backup mode. Where, then, is the spike
protection? Plug-in UPSes simply forget to mention these
details. That UPS is for data protection from blackouts and
brownouts - especially if the harddisk filesystem is FAT.
Effective hardware protection is called 'whole house' as
discussed previously. Spike earthed before it enters the
building. A protector more effective and typically 10+ times
less expensive per protected appliance. But again, read that
previous discussion. The plug-in UPS really only claims
protection from blackouts and brownouts.

 

[MrB]

Two weeks ago, we had a power problem in which the neutral became
ineffective. Somehow, this put 220 on 110 volt lines. There were six
computers running, plus some printers. They were all plugged into modestly
priced surge protectors. All of the SP's blew out. One even burned slightly.
Four of the computers still functioned properly. One required a PS change in
is back on line. The other failed computer is so old, I cannot find a power
supply for it. The printers survived. Since we had just moved the equipment
into a new (old) building, I insisted on new SP's for everything.

 

[V W Wall]

Two weeks ago, we had a power problem in which the neutral became
ineffective. Somehow, this put 220 on 110 volt lines. There were six
computers running, plus some printers. They were all plugged into modestly
priced surge protectors. All of the SP's blew out. One even burned slightly.
Four of the computers still functioned properly. One required a PS change in
is back on line. The other failed computer is so old, I cannot find a power
supply for it. The printers survived. Since we had just moved the equipment
into a new (old) building, I insisted on new SP's for everything.

You are describing a "floating" or open neutral. In this situation two 110 V
circuits are placed in series with 220 V appearing across the combined circuit.
If the load on one side is greater than that on the other side, the 220 volts
will split inversely to the loads. The side with the smaller load will see a
much greater voltage. In this case the SPs may try to clamp the voltage, but
can only sustain a fixed amount of energy. They will then burn up. They are
designed to clamp short voltage spikes, not a sustained higher voltage. If
their designed clamp voltage is higher than the applied voltage, they will
do nothing. I'm looking at a typical MOV, (metal oxide varister), used in
130 V surge protectors. It has a minimum clamp voltage of 185 V and a maximum
of
225 V, and can sustain energy of 70 Joules. You can see most of these would
have burned up.

A surge protector is not useful in a case like this. If correctly sized,
a line fuse may protect equipment, or the circuit breaker may below before
damage occurs. Not a happy situation in any case!

In an old building it's a good idea to check every outlet for neutral
and ground integrity before plugging in any equipment.

Virg Wall
--

Any sufficiently advanced technology
is indistinguishable from magic.

Arthur C. Clarke's Third Law

 

[Not so quick]

You didn't mention sags. It seems to me that I get a lot
of lights blinking off and on. Two or three times a week.
Sometimes the computer resets.

 

[Mike Walsh]

A good UPS will kick in when the voltage sags instead of only when power is completely lost. The Belkin UPS I am using now is set to kick in when the line voltage drops to 95 volts.

 

[Not so quick]

A good UPS will kick in when the voltage sags instead of only when power

is completely lost. The Belkin UPS I am using now is set to kick in when the
line voltage drops to 95 volts.
Do you consider sags and short total interruptions to be
a cause of computer problems? Do you have an idea why
the lights seem to flicker and the computer screen does too?

 

[Chris Martin]

I'm using an APC Back UPS LS 700, and it works great. I live off in a new
development in the middle of a forest, and they are constantly working on
new houses and such, so we get lots of 'accident's happening with the power.
It's wonderful to be playing a game when the power goes out and have the
game keep on playing. This model comes with a USB connection that allows
the power supply to tell the computer that it is running on battery, and if
you configure it to, it will safely put your computer into hibernation so
your data is not lost. It kicks on when there are sags and spikes to
regulate power flow, and keeps logs of all of the information.. I can tell
you now that in the last four weeks my battery has kicked on for blackouts 4
times, undervoltage once and from noice 9 times.

Good luck with your power,

~Chris Martin

A good UPS will kick in when the voltage sags instead of only when power

is completely lost. The Belkin UPS I am using now is set to kick in when the
line voltage drops to 95 volts.

 

[w_tom]

A sag is a brownout. All computers must work just fine even
when 120 VAC drops (sags) to 90 VAC. This was a defacto
standard 30 years ago and is required in Intel ATX specs.
That means AC voltage drops so low that incandescent lamps are
at maybe 35% intensity. How often does your voltage drop that
low?

Yes, not all power supplies meet those specs. We see them
often because too many in N America only purchase using one
spec - price. Power supplies must contain many functions.
How to sell a power supply at higher profit? Forget to add
those functions and sell it for maybe $40. Too many computer
experts don't even understand basic electrical concepts which
is why too many clone computer users have strange problems.
Posted above are numbers found in the numerical specs provides
by acceptable power supplies. Information that minimally
acceptable power supplies provide because they actually meet
those specs.

Then we have people who fix things without first learning
why the problem exists. Their solutions include 500 watt
power supplies (Home Improvement's "More Power" solution) and
plug-in UPSes. Expensive solutions because the original
supply was not purchased based upon technical requirements.
All computers must work just fine - even startup with the
maximum load of peripherals - when 120 VAC line is only 90
VAC. That 90 VAC is called a sag or brownout.

If power is lost for more than 15 milliseconds, then a
computer can shutdown. This can result in data loss on FAT
filesystem disks. Just another reason we want NTFS
filesystems on our hard drives - or need a UPS for data
protection.

 

[w_tom]

First, a bad neutral does not create 220 volts on 120 volt
wires. It creates something typically much less than 220
volts.

Second, how many of those power supplies are universal type
- good for all voltages from 90 to 265 volts AC?

Third, as posted by another, those surge protector are only
for very short duration spikes. Even worse, a transient too
small to damage the computer can damage those protectors
leaving computer completely exposed.

Fourth, even Computer Business Equipment Manufacturer's
group specs (a most minimal spec) required 120 VAC equipment
to withstand voltages up to 600 without damage. Other
conditions apply beyond the scope of this discussion. But the
point remains - computers are some of the most resilient
electronics in the building. Plug-in protector doesn't offer
effective solutions, in part, because that protection already
exists inside power supply.

Neutral line problems can result in 130+ volts on AC line.
Made obvious because even 126+ volts causes incandescent light
bulbs to last less than 1/2 their hours of life expectancy.
And yet every electronic must have no problems with voltages
even at 130+.

Again, more facts that overpriced, undersized plug-in
electrical solutions forget to mention. Profits being too
high to tell all facts. If that plug-in UPS does not have a
dedicated earthing connection, OR if it forgets to even
discuss earthing, then it does not provide effective transient
protection ... which is why they avoid all discussion about
earthing to make the sale.

 

[V W Wall]

First, a bad neutral does not create 220 volts on 120 volt
wires. It creates something typically much less than 220
volts.

A normal circuit is either 110/220V or120/240 V.

As I said before, a "bad", (open), neutral creates voltages inversely
proportional to the load on each "side". If the circuit on one side
of the 120/240 V circuit is drawing 10 A, and you have a computer,
or any other load drawing 1 A, the voltage on that side will increase
to ~218 V.

Second, how many of those power supplies are universal type
- good for all voltages from 90 to 265 volts AC?

Most computer supplies have a switch on the back which determines if
it uses a voltage doubler circuit to produce ~345 V DC (set to 120 V),
or directly rectifies the 240 V input to obtain the same DC voltage.
A few supplies detect the input voltage and react accordingly.

Third, as posted by another, those surge protector are only
for very short duration spikes. Even worse, a transient too
small to damage the computer can damage those protectors
leaving computer completely exposed.

The MOV (metal oxide varistor) I cited can sustain 6500 A, but
omly for a few microseconds. Its total energy absorption is
70 Joules. This is a larger MOV than many inexpensive surge
protectors use.

Fourth, even Computer Business Equipment Manufacturer's
group specs (a most minimal spec) required 120 VAC equipment
to withstand voltages up to 600 without damage. Other
conditions apply beyond the scope of this discussion. But the
point remains - computers are some of the most resilient
electronics in the building. Plug-in protector doesn't offer
effective solutions, in part, because that protection already
exists inside power supply.

Your are confusing input line voltage with hi-pot requirements.
At 600 V, the input capasitors in a PC supply would have 864 V
across the two, or 432 V each, rather than the normal ~175 V.
I have never seen a PC supply with input capacitors rated this
high.

Neutral line problems can result in 130+ volts on AC line.

It can go much above 130V. See above discussion and apply simple
Ohm's law to the circuit!

Made obvious because even 126+ volts causes incandescent light
bulbs to last less than 1/2 their hours of life expectancy.
And yet every electronic must have no problems with voltages
even at 130+.

Again, more facts that overpriced, undersized plug-in
electrical solutions forget to mention. Profits being too
high to tell all facts. If that plug-in UPS does not have a
dedicated earthing connection, OR if it forgets to even
discuss earthing, then it does not provide effective transient
protection ... which is why they avoid all discussion about
earthing to make the sale.

One thing we agree on--surge protectors won't protect against a
sustained over voltage.

Virg Wall
--

Any sufficiently advanced technology
is indistinguishable from magic.

Arthur C. Clarke's Third Law

 

[w_tom]

Bad neutrals do not create the 218 volts, as indicated,
because system contains other components. Components such as
earth ground that minimize that problem more to something in
the 130+ volt range.

If a failed neutral caused 218 volts, then every
incandescent light bulb would burn out immediately. Even 150
volts would cause extremely quick light bulb failure.

The term was "universal" supply. Universal supplies make
that red voltage switch extinct. Some computers do not have
that red switch because they are universal supplies. Many, if
not most monitors contain universal supplies that work 90 to
265 volts - which is why monitors protected themselves. How
many of those computers had universal supplies?

I did not say 600 volts continuous and stated those details
were beyond the scope of this discussion. The point remains:
plug-in protectors did not protect those computers. Those
computers protected themselves. Failed neutrals rarely create
anywhere near to 220 volts on 120 volt wires. How many
household incandescent bulbs burned out that day? If not all,
then nothing close to 200 volts was put on those computers.

Failed neutrals are but another reason why earth ground is
so essential to human protection. In a classic case, a failed
neutral connected to a house that was missing earth ground.
Gas meter exploded as a result. So essential earth ground and
other 'unofficial' connections are why a failed neutral in
that example would not create 200+ volts.

 

[V W Wall]

Bad neutrals do not create the 218 volts, as indicated,
because system contains other components. Components such as
earth ground that minimize that problem more to something in
the 130+ volt range.

Earth ground has nothing to to with the voltage created by a
failed (open) neutral.

If you don't know how to use Ohm's law, put your 3 1/2 digit
meter on the case I cited!

If a failed neutral caused 218 volts, then every
incandescent light bulb would burn out immediately. Even 150
volts would cause extremely quick light bulb failure.

*Every* failed neutral will not produce this effect. I think the
OP said 220 V *was* produced.

Many circuits are wired with lighting circuits separate from outlet
circuits. As I said, it depends on the way the 120/240 V loads
are balanced.

I had a neutral "open", (bad connection at a wire nut), in my home.
A freezer with 1/4 HP motor was on one side, and a turned off
microwave oven on the other. The oven was "protected" with a MOV,
possibly to protect other appliances on the same circuit from the
oven. In any event the MOV burned out when the freezer attempted to
start. Luckily, nothing else on the oven side of the circuit was
turned on. It was not a lighting circuit, so no lamps burned out.

Most codes now require that such heavy current draw appliances be
on a separate circuit, but they still allow them to be on one
side of an outlet string.

The term was "universal" supply. Universal supplies make
that red voltage switch extinct. Some computers do not have
that red switch because they are universal supplies. Many, if
not most monitors contain universal supplies that work 90 to
265 volts - which is why monitors protected themselves. How
many of those computers had universal supplies?

How many "universal" supplies are in use? Many? Most?
Let's take a poll. How many have monitors that work on 90-265 V?

I did not say 600 volts continuous and stated those details
were beyond the scope of this discussion. The point remains:
plug-in protectors did not protect those computers. Those
computers protected themselves. Failed neutrals rarely create
anywhere near to 220 volts on 120 volt wires. How many
household incandescent bulbs burned out that day? If not all,
then nothing close to 200 volts was put on those computers.

Lighting circuits and outlets are often on different circuits.
I agree-- 220 V will burn out a 110 V lamp! Check your local
electrical code as to circuit requirements.

Failed neutrals are but another reason why earth ground is
so essential to human protection. In a classic case, a failed
neutral connected to a house that was missing earth ground.
Gas meter exploded as a result. So essential earth ground and
other 'unofficial' connections are why a failed neutral in
that example would not create 200+ volts.
Huh!

Virg Wall
--

Any sufficiently advanced technology
is indistinguishable from magic.

Arthur C. Clarke's Third Law

 

[MrB]

Mr w-tom,

You were not there. 220 volts was measured on the line with a digital
voltmeter. Believe what you want, it happened. My main point was that most
of the computers survived with minor or no damage, even though the surge
protectors blew out. It was good protection for the price.
MrB

 

[w_tom]

If 220 vac existed, then verify integrity of your earth
ground system. For those readings to exist, then 220 volts
was also in your earthing system - unacceptable and
potentially dangerous. You were suffering a failure
equivalent to the house with exploding gas meter. 220 volts
not possible if the earthing system is intact. It may not be
your earthing connection either. See pictures for examples of
what to look for on utility pole with transformer:
http://www.tvtower.com/fpl.html

Now if that volt reading was correct, how many incandescent
bulbs blew out immediately? If that 220 volts did not damage
incandescent bulbs immediately, then something is seriously
inconsistent; 220 volts did not exist.

Again, if surge protector blew out, then protector provided
no protection as V W Wall notes. Protectors blew out - maybe
vaporized - stopped providing any protection because they were
undersized. In the meantime, 220 volts continued past 'burned
out' protector and directly into PC.

Too many inconsistencies. 1) Surge protector vaporized in
milliseconds - became nonexistent - but computer confronted
220 volts for minutes after the protector failed. That means
computer protected itself while surge protectors remained
nonexistent. 2) 220 volts on 120 volt circuit - but it did
not immediately blow out incandescent bulbs (and many every
other appliances)? Not possible. 3) 220 volts on 120 volt
circuit but earthing grounds intact? Not possible.

Facts as were posted are not consistent. If that 220 volts
did exist, then, first, you have a serious - very serious -
human safety problem in that missing earthing system.

 

[kony]

is completely lost. The Belkin UPS I am using now is set to kick in when the
line voltage drops to 95 volts.

Do you consider sags and short total interruptions to be
a cause of computer problems? Do you have an idea why
the lights seem to flicker and the computer screen does too?

If you feel the problem starts within your home, you need to contact
an electrician to resolve this. If it starts outside your home you
need to contact the electric co. A solution specific to the computer
might include a quality power supply, preferribly with Active PFC,
which are the type typically accepting wider range of voltages without
a voltage selector switch on the back.

As for an UPS, the mid-to-high end models may have a line conditioner
built in, may actually call it a conditioner or perhaps some mention
of voltage regulation.

 

[w_tom]

Important point to all lurkers. One indication of a missing
neutral is quickly identified by snow. If snow is melting
first around that earth ground rod, then a potentially
defective neutral should be visually inspected.

 

[kony]

Important point to all lurkers. One indication of a missing
neutral is quickly identified by snow. If snow is melting
first around that earth ground rod, then a potentially
defective neutral should be visually inspected.

Where to find snow? Ebay?

;-)