3 blown Power supply's in 6 months.

[w_tom]

Wonderful. One word is technical proof that you understand
the concept.

That fuse would blow as a result of hardware damage. That
is what fuses do. Protect human from further damaged created
by the initial failure. The primary function of fuses - to
protect humans. Somehow the excrement of a horse proves this
all wrong? Is that the fact you can post? Well I'm sorry.
That fact stinks.

 

[w_tom]

A few basic facts that Leythos forgets. Overloaded power
supplies have dedicated functions to protect themselves AND
without damage. And without using fuses. This function was
industry standard even 35 years ago. Industry standards even
demand it. The overloaded power supply must work just fine -
no parts replaced - after the overload is removed.

No fuse to protect power supply hardware from overloading.
There may be fuses to stop a wire fire. But Leythos again
demonstrates knowledge before learning facts. Power supplies
(and stereo power amps) contain internal protetion so that
overloading does not damage the equipment. Fuses are too
crude to accomplish that task. But a fuse can eliminate fires
that might harm humans after semiconductor failure has
occurred.

"Lamer" - Leythos is again demonstrating a wealth of
supporting technical facts - complete with numbers. Just what
I would expect from junk science reasoning.

 

[Guest]

I bought a couple really nice Antec 550W PSU units, they were nice
except for one little flaw - they contain two variable speed fans that
run based on temperature of air flowing through the PSU. I found that
the fans ran around 1100RPM and were unable to keep the system cool, I
opened the cases and setup the fans to run on a fixed +12v and they
run
around 3500RPM and the systems stay a lot cooler now.

I got the Fortron Aurora because of its larger 120mm fan thinking it
would spin slower to keep it quieter. Well, it is quieter than the
prior PSU with an 80mm fan but not as silent as I thought it would be.
It has the potentiometer on the back to let me adjust its minimum fan
speed but a thermocouple dictates the absolute minimum speed and that is
usually higher than what I set with the potentiometer (i.e., the
thermocouple during hot temps overrides what I set when cold), so the
PSU keeps itself cooler despite me trying to reduce the fan speed too
much. I was surprised that the fan got noisy after only about 4 months
and I had to replace it, but sometimes even good-brand products fail.

Since the airflow rate is the same with 2 fans as it is with one fan
(there might be a slight increase), and from what I've read and
discussed with those who actually design power supplies, the second fan
is only there as a backup. Only one fan is really needed to meet the
cooling requirement. That's why in many designs there is one fan that
always spins at a constant speed because it is the backup fan (typically
slower but at the minimum needed for airflow). Should one fan die, the
other fan is the backup to provide the minimum airflow rate. You sure
BOTH fans were thermo-controlled?

I've often found that opening up the case improves cooling, not by
removing the side panel but by replacing drive bay plates with grills
(or drilling them out to make a grill), using ventilated side panels, or
even by leaving off the bottommost card slot blank. Even cleaning up
the interior and orienting the flat cables to be inline with the airflow
will help (a flat ribbon cable perpendicular to the airflow reduces it
due to turbulence). A fan cannot move more air than gets delivered to
it. Turn on a fan and cover with cardboard, and the airflow rate is
zero. Too many times I've seen compact or slick cases whose intake was
too restrictive. I've even seen where reversing a backpanel fan (from
exhaust to intake) would reduce temperatures (CPU and case), often
because of poor positioning of side-panel fans and because the PSU fan
could actually handle a higher airflow rate than it was delivered to it
before. Sometimes experimentation bears out what logic (which is
usually just common lore) says can't happen.

 

[w_tom]

Good show. Thanks to powers that be (ie Mickey Mouse), you
can now demand royalties for something like seventy five years
- unless someone with deep pockets decides to sue. But then
that is a different 'human safety' issue using different
protection devices.

 

[Richard Urban]

I want the fuse to blow before damage to the hardware occurs. If the fuse is
sized for the hardware's optimal current draw, that is what will happen.
Then the hardware can be electrically repaired, the fuse replaced and the
machine is again happy.

By the way, I have repaired thousands of machines over the years that have
blown fuses. With few exceptions they were all repairable and never again
blew another fuse. And I am happy to say that no one died in the process. I
guess the fuse saved their lives!

That is great, but I still fuse to protect the equipment.

--
Regards,

Richard Urban

aka Crusty (-: Old B@stard

If you knew as much as you think you know,
You would realize that you don't know what you thought you knew!

 

[Richard Urban]

Boy, you do have a one track mind. Perchance did you screw up years ago
while you were learning and severely cause injury, or worse, to someone!
That would explain it.

--
Regards,

Richard Urban

aka Crusty (-: Old B@stard

If you knew as much as you think you know,
You would realize that you don't know what you thought you knew!

 

[Leythos]

A few basic facts that Leythos forgets. Overloaded power
supplies have dedicated functions to protect themselves AND
without damage. And without using fuses. This function was
industry standard even 35 years ago. Industry standards even
demand it. The overloaded power supply must work just fine -
no parts replaced - after the overload is removed.

No fuse to protect power supply hardware from overloading.
There may be fuses to stop a wire fire. But Leythos again
demonstrates knowledge before learning facts. Power supplies
(and stereo power amps) contain internal protetion so that
overloading does not damage the equipment. Fuses are too
crude to accomplish that task. But a fuse can eliminate fires
that might harm humans after semiconductor failure has
occurred.

"Lamer" - Leythos is again demonstrating a wealth of
supporting technical facts - complete with numbers. Just what
I would expect from junk science reasoning.

I stand by my statement - you are really a lamer and troll. Not all
power supply units are designed to protect their circuits against a dead
short, not all are designed to handle over-current conditions. Sure,
many of the nicer ones are, but you seem to have very limit scope of
contact with the real world.

Heck, we still had power circuits in F14 control systems that were fused
10 years ago - so much for your 35 years. Oh, and as late as the early
90's there were many non-switching PSU's in use in a varied number of
devices.

You need to get off your small minded, limited experience, little bit of
knowledge, and learn that you don't seem to know jack-shot about a lot
of think kid.

 

[Leythos]

I stand by my statement - you are really a lamer and troll. Not all
power supply units are designed to protect their circuits against a dead
short, not all are designed to handle over-current conditions. Sure,
many of the nicer ones are, but you seem to have very limit scope of
contact with the real world.

Heck, we still had power circuits in F14 control systems that were fused
10 years ago - so much for your 35 years. Oh, and as late as the early
90's there were many non-switching PSU's in use in a varied number of
devices.

You need to get off your small minded, limited experience, little bit of
knowledge, and learn that you don't seem to know jack-shot about a lot
of think kid.

Open a google search page, enter "power supply fused protection" and see
just how many AC and DC power supply units come with fuses for
protecting the power supply. Bet you won't understand what you see

 

[w_tom]

Problem of using fuses for hardware protection is their very
wide range of 'protection'. To appreciate the problem, learn
about the well understood I^2t curve. For example,
semiconductor devices will fail in microseconds. A
microseconds transient that exceeds the fuse current ratings
by factors of tens will not even blow the fuse. The fuse
takes tens of milliseconds (or longer) to blow. Fuse only
blows long after damage has occurred.

Fuses will do better on equipment that can take massive
overcurrent for a long times, such as large motors.

Review the numbers. For example, a 20 Amp fuse for
automotive protection would conduct 100 amps for 0.5 seconds
before opening. Or 40 amps for 9 seconds. And this assumes
ambient temperature is constant. The fuse must be sized to
not blow also at over 100 degrees F. However the same fuse
will now require 10% or more current to blow in winter
temperatures. Then there are waveforms for that overcurrent.
Then the manufacturer recommends adding another 20% margin of
safety.

We have assumed an ideal overcurrent - a square wave. That
100 amps might take twice as long to trip a 20 amp fuse if
current only averages 100 amps but really peaked at 200+ amps.
Variations mean that sizing a fuse for hardware protection
becomes difficult if not impossible.

This 20 amp fuse would be selected typically for loads that
may peak around 10 amps or less just to avoid nuisance
tripping. And yet a 100 amps short circuit is required could
make the fuse open in less than one second. IOW the fuse of
for protection after damage has occurred.

For UL approval, a fuse must open at 135% of rated power
within one hour. It must open within 2 minutes is the
overcurrent is 200%. That means to protect a 1 amp load, the
two amp fuse (the smallest selected so as to avoid most
nuisance tripping) would conduct 4 amps through the protected
appliance for minutes. Or 10 amps for 0.1 seconds. Ten times
more current through a 1 amp item - where is the hardware
protection? Does not exist.

Fuses were not for hardware protection. Fuses are installed
first and foremost for human safety. These are numbers.
Others are invited to demonstrate knowledge of numbers rather
than post "horseshit", "lamer", and other technical facts.

Fuses are excellent at stopping wire fires. The standard 20
amp electric wire should handle hundreds of amps without
damage (and fire). Long enough for a fuse to eventually open.
But fuses are woefully insufficient at avoiding appliance
damage. That I^2t curve, well understood by those with basic
electrical background, demonstrates the problem. Time even
tens of milliseconds for faster fuses is woefully too long to
protect electronics - such as a power supply.

Fuses don't even claim to protect appliances. Fuses are
installed to blow after a failure has happened. After current
well exceeds what is normal rated consumption. The fuse
provides human protection after damage has occurred. Above
numbers demonstrate that fact. Numbers rather than insults
demonstrate that fuses do not protect hardware. Fuses blow
after damage has occurred; for human safety.

 

[w_tom]

Well again Leythos uses words to demonstrate the quality of
his technical knowledge. But Leythos, you might learn
something. Numbers are posted elsewhere in this thread.
Numbers. Remember those things you post insults to avoid?
You only stand by insults. As usual, insults remain your only
technical fact. Numbers? Do you know any good numbers?

Meanwhile for the benefit of others more interested in
reality, linear supplies routinely included current fold back
limiting even 35 years ago. For others, numbers for fuses are
provided in another post to Richard. Numbers that demonstrate
why fuses cannot protect electronic appliances.

 

[w_tom]

Woww. Such hate. Such acidity even to a little humor. Are
you sure your name is not Leythos? Lighten up, son.

 

[Leythos]

Well again Leythos uses words to demonstrate the quality of
his technical knowledge. But Leythos, you might learn
something. Numbers are posted elsewhere in this thread.
Numbers. Remember those things you post insults to avoid?
You only stand by insults. As usual, insults remain your only
technical fact. Numbers? Do you know any good numbers?

Meanwhile for the benefit of others more interested in
reality, linear supplies routinely included current fold back
limiting even 35 years ago. For others, numbers for fuses are
provided in another post to Richard. Numbers that demonstrate
why fuses cannot protect electronic appliances.

And again you miss a lot, you miss small 24VDC PSU's, the fused circuits
to cover overload on amps, the fuses on all sorts of hardware.

I got news for you - fuses don't just protect LARGE MOTORS, they
protect a entire range of devices that you ignore due to your complete
lack of understanding anything posted in any Usenet group you
participate in.

What part of numbers for power supply units that HAVE FUSES did you miss
- there are hundreds of sites in that google search I presented you with
that you seem to have missed.

Oh, and no one uses Fuses for microsecond protection of anything -
everyone already knows that fuses are slow devices, even fast acting
fuses are slow.

Heck, I even have old Radio's that have 1A or 2A fuses in them to
protect the power output from simple transistors used in the regulator
circuits - but I'm sure you will tell me that those only blow after the
unit is damaged, even though I've replaced them, without replacing
anything else, and the units still work after more than 20 years.

So, come on, tell us again how fuses only protect damaged devices from
injuring people. You lost all credibility when you started your BS this
time.

 

[w_tom]

Fuses in that radio would be required by the UL so that it
does not kill someone. If fuses are routinely blowing, then
fuses are too small - nuisance tripping. That too
demonstrated in another post with numbers.

To protect electronics, a fuse must blow in microseconds.
But again, you damn the numbers. You know better because
undersized fuses in a Radio are nuisance tripping. That alone
is sufficient proof of what? Next you will claim a UPS
provides protection that even its manufacturer does not
claim. Why? Your speculation, as ususal, is proof enough.
Numbers be damned.

For others, numbers are provided elsewhere. Fuse takes
numerous seconds or minutes to protect from an overload. But
after damage has occurred, the higher current will quickly
open the fuse - to protect human life.

 

[Leythos]

Fuses in that radio would be required by the UL so that it
does not kill someone. If fuses are routinely blowing, then
fuses are too small - nuisance tripping. That too
demonstrated in another post with numbers.

There you go assuming you know why they blew, and that they blew many
enough times to mean they were too small for the reason they were
installed. Fuses that have blown 3 times in 20 years is not significant
in some circuits, but I don't expect you to have any experience in that
area either.

To protect electronics, a fuse must blow in microseconds.
But again, you damn the numbers. You know better because
undersized fuses in a Radio are nuisance tripping. That alone
is sufficient proof of what? Next you will claim a UPS
provides protection that even its manufacturer does not
claim. Why? Your speculation, as ususal, is proof enough.
Numbers be damned.

You've got to be kidding - many devices can take minutes of excessive
load without being damaged, some hours, you really have never worked
with electrical devices of a varied nature - have you?

For others, numbers are provided elsewhere. Fuse takes
numerous seconds or minutes to protect from an overload. But
after damage has occurred, the higher current will quickly
open the fuse - to protect human life.

Again, you miss the mark - fuses do take time to open, some open in
milliseconds, some open in seconds, some longer, but since you've not
posted any specific fuse and the load you are suggesting, we can't
really suggest if the fuse blows quickly or slowly.

If I draw 1.05A on a 1A fuse it may never blow, or it may blow after
minutes, but if I draw 1.7A on it, it's going to blow quickly - even
though all of the devices in the rest of the circuit could handle the
load for several minutes without damage - the idea is that the fuse
blows as quickly as needed to protect the circuit and it's parts.

Ever hook a multimeter to a 600V line on the wrong setting? The little
315MA fuse blows in less than a millisecond (I would have to guess), but
there is no damage to the device, and the foil on the circuit board
would vaporize before damage to human, so there was no reason to have it
there to protect the human, it was there to protect the foil traces on
the circuit board or other components inside the multimeter.

None of these REAL examples have anything to do with protecting a HUMAN,
it's about protecting the device.