Are mains surge protectors needed in the UK?

"David Maynard" wrote in message
...
half_pint wrote:

"David Maynard" wrote in message
...

half_pint wrote:


But electronic devices are not connected directly to the mains they
are connected to a power supply which is *designed* to copy
with large cueernts.

I suppose you think that means something but it's irrelevant to the

point

that electronic devices react to electrical faults hundreds of times

faster


than any fuse can. More to the point, any current that could possibly

blow

a fuse is the RESULT of a failure which, by definition, means the fuse
cannot 'protect' from it as it's already happened.


No we are talking about a surge in current from outside the house

No, we're talking about a voltage surge.


Voltage never causes device failure,

Research it and learn, or remain ignorant. Your choice.

Shut up.



so to speak. That surge must go through the fuse first, strictly

speaking,

well, at leaaast at the same time anyway.

There will be no current unless something conducts.


Brilliant!!!


I.E. If there were no devices plugged in (or wired in) the only effect
would be a voltage spike on the interior power lines, but no current
flow
per see (besides leakage).


And no current flow = no damage.

Research electrostatic breakdown in semiconductors.

Post graduate research you mean?



If, however, a susceptible device is connected to the power line and the
voltage spike is sufficient to cause electrical breakdown then the
device
fails and may pull excessive current as a result of the failure, which,
if
severe enough, will blow the fuse. But the failure has already occurred
by
the time the fuse sees anything, much less blows.


Only current flow causes damage,

false.

current flow blows fuses.

true

heat strictly speaking.


A main spike hits the robust components of the PSU first

I suppose you want to ignore modem lines.


I dont connect my comms line to the mains.


these are not sensitive to high voltages,

Depends on how high the voltage.

infact the voltages inside
them are dangerous to humans,

Some are; others aren't.

The fact of the matter is that you know nothing of which you speak.

********.



OK if you connect one leg of your 3GHz pentuim to the
mains live connection and the other leg to earth you will probably

damage it


but I am not recommending that.




And it's inherent to the nature of electronics.
By the time an electronic device is pulling excessive current
whatever

is


at fault inside has long since gone to the happy hunting grounds, or

else


it would not be pulling excessive current. And there's nothing you
can

do


about it by 'sizing' the external fuse as the failed device could be
a
100mw component inside a 200 watt computer where the normal
operating

power



fluctuations are hundreds of times larger.



I dount there are many 100mw components in a PS and even if there
were and they did blow they would protect your computer.

For that to even begin to make sense you'd first have to consider a

blown

power supply as the device still 'working', but I doubt most people
do.

Further, I have no idea what makes you think a 'blown' component in
the

PSU


will 'protect' the computer. All one need imagine is the reference

voltage

zener blowing, resulting in lord knows what voltage being thrown into

the

system and destroying massive numbers of components.


A zener diode is already 'blown' so to speak, thats how they work.

No, it isn't.


The voltage across them is basically the same whatever the input

voltage.

An obvious contradiction, as stated.


Rubbish that is how they are designed to work!!

There cannot be "whatever the input voltage" to the one and only device in
your statement, the zener, if it's "the same."



A zener conducts when the voltage across it reaches a certain level,
otherwise is does not conduct, and the source better be current limited,
most commonly by a series resistor, or else the zener will self
destruct.
In that case, by over heating.


Ans of course they are always current limited by a series resirtor in
appliances.

Well, no. That just happens to be the cheapest and most common means when
they're used as a simple voltage reference. It is not the only way they're
used.


Essentially it is a grain of sand,

Not hardly.


I am afraid it is.

You apparently haven't a clue.

sure

It's like saying silicone is 'essentially sand', and has the properties of
sand. Or that glass is 'essentially sand', and has the properties of sand.

One has to go back to before even the days of alchemy to find such
absurdities promulgated as 'knowledge'.

its not going to melt,

'Melting' has nothing to do with it.

What?

Simple enough statement.


at least not
before
other metal components vapourise. And the first component to vapourise
will be the fuse in the plug, you can be sure of that.

No offense but you really don't understand semi-conductors at all.


You are maing no sense ar all.

That's probably how a medieval alchemist would feel about a discussion on
quantum mechanics, and for the same reason.

Are you on drugs?


That is, of course,
why all decent PSUs include over voltage protection on the power
rails.


Ah hah!!



And
while you may gleefully scream "ah hah!," as if that means something
to
your case, it isn't done with fuses because fuses are too slow to

protect

electronic components.


I think you will find 99% of surge protectors contain a fuse, which is
a

bit

odd really if they are surplus to requirements?

No one ever said they were 'surplus'. The problem is you don't
understand
the nature of electronics and the purpose of various protection devices.


I do

It is obvious you don't and what's further obvious is that you refuse to
learn a thing about it.


A fuse blows on a sustained current fault and breaks the connection: a
preferable situation to continuing to draw fault current because, for
one,
it prevents fires.

That has nothing to do with 'protecting' what is already a damaged
device
causing the current fault.


You don't really understand electricity do you?

I have already provided you with corroborating authoritative sources for
my
explanations.

I challenge you to provide one for your absurd contention that voltage
cannot damage semiconductors.

If I have a billion volts at one end of a 1mA wire fuse and a billion volts
at the
other end will it blow?

Get some education.





The issue isn't 'where' the fault occurs in the device but that a fuse
simply cannot 'protect' from it (voltage induced failure).



However before it did blow it would probably required a
several fold increase in current for a substained period which
would obviously blow the fuse first.

This is where you are sorely mistaken as you seem to think that the
only
way any device, of any kind, fails is by current induced heating but

that

is simply not the case with electronic devices. Too much voltage, as
perhaps induced by a surge, will instantly destroy semi-conductor
components; after which they may simply do nothing or, more common,
draw
excessive current. At which point, anything a 'fuse' detects is long

since

after the fact.

No that current has to come in via the fuse which is designed to fail
as
quickly
as possible, as opposed to other components which are designed *not* to
fail.

You're never going to understand it till you get it out of your head
that
'excessive current' is the only thing that damages semi-conductors.


Heat is the only souce of damage, and current not voltage
produces heat.

Wrong, and I've provided authoritative sources to corroborate it.

Garbage.


(Heat can destroy them too but that isn't the mode we're talking about

with


surge protection)



And if you are saying that semi conductor devices are inherently
sensitive to current then obviously we would make fuses out of them.

It is your mistaken notion that only 'current' causes failure that
leads
you to invalid assumptions.


But I am right of course, *only* current *ever* causes electrical

failures.

A semiconductor device, or any electrical device will work quite

happilly

a 1 billion volts.

Surely you jest.

Why in the word do you think power supplies, much less multi-voltage

units,

even exist if electronics works 'quite happily' at just any old voltage?

I think you missed the point.

If you thought so that certainly doesn't elaborate, but don't bother as
I've had enough of your absurdities anyway.

I explained above, voltage is relative,



However semiconductors are make out of silicone which has
an extremly high melting point.

Which is irrelevant because that is not what causes device failure.


Heat is the only cause of device failure. Ever. Period.

Just plain wrong.

Really now, even your own decryption, as misguided as it is, contradicts
THAT absurdity because, if it were true, there would never ever be an
electronic failure, unless someone shoved it inside a 900F oven. And
that
is clearly not the case.


You don't have to heat the whole device, the damage is usually localised

You actually stumbled onto something that's halfway correct:

Its all correct anad i didnt stumble I knew where I was going.

you can have
localized heating. It's not, however, very relevant to the point because
the thermal conductivity of semiconductors won't allow so dramatic a
difference, when compared to your claimed '900F' destruction point, as to
matter to the illustration. So we need fools shoving them into 700F ovens,
instead of 900F ovens, before any device would ever fail. It is still an
absurdity.

Btw, the melting point of silicon isn't 900F, it's (much) higher, but I'm
using your numbers to illustrate that even your own 'theory' is
irrational.

I know it is higher but some of the doping agents are lower so I
compromised. :O)


(we are basically talking about
sand) indeed silicone has replaced asbestos as a safer heat
resistant material.
http://www.candochefs.com/silbakmat1.html

" Use in up to 900 degrees F! "

Obvioulsy fuses are *designed* to melt quickly
at low temperatures.

Semiconductors materials are probably never damaged
by heat, at least not untill long after the metalic contacts have
vapourised.

'Melting' is not the failure mechanism of semi-conductor devices.


Yes it is.

No, it isn't. And I'd advise you to go learn something about
semi-conductors before you make such statements because they make it

rather

obvious you have no idea how they work.


I have every idea how they work, much more so than you.

Feel free to quote a text book, or some other authoritative source, that
supports your fantasies.

I have a brain so I need no text books.



And even if you did have a
'constant power consumption' electronic device, for which you could
'tightly' size a fuse, electronic components can, and do, go into
catastrophic failure hundreds of times faster than a fuse can blow.

Surge -- component failure -- excessive current -- fuse blows




They blow before the device draws enough current to be damaged,
that

is

how they are designed.

That is certainly the myth. It is not, however, reality.


You don't have a huge backlog of expensive surge protectors to shift
by any chance?

I don't 'sell' anything nor is it any skin off my nose if your
computer

is

damaged because you think a fuse will 'protect' it.

Nice try buddy, uk.comp.vendors, pull the other one, I wasn't born
yesterday.

I'm posting from alt.comp.hardware.pc-homebuilt.



There of dozen of devices in my home which contain IC's none has ever
failed due to a power surge, zilcho.

And you think that 'proves' what?

My point and my arguement, unsurprisingly.

Since you made no 'point' there is nothing it could.

probably went over your head.



There are also many IC's in my car which regularly gives me a big zap
of
static electricity, I can assure you that the shock has effected me far

more

than
my car stereo etc....

Oh, really? And what were you doing with the case to these devices open
so
that you were getting a 'static discharge' from the 'ICs'?


Still a huge voltage surge and no anti - surge device yet MIRACULOUSLY
ALL THOSE SENSITIVE DEVICES WERE TOTALLY UNDAMAGED
HOW STRANGE????????

Not at all. It has nothing to do with ICs being 'immune' from static
voltage damage but it's obviously useless to attempt educating you about
anything.

Its fact though.


But since you bring it up you could expand your horizons by doing a web
search on ICs and static electricity and, in particular, ESD protection.


Already have, not that I needed to, everything I found bacjed my
case.

ROTFLMAO


Here's one to get you started:
http://www.informit.com/articles/art...21704&seqNum=3

"In general, MOS devices are sensitive to voltage spikes and
static-electricity discharges. This can cause many problems when you
have
to replace MOS devices, especially complementary-symmetry metal-oxide
semiconductor (CMOS) devices. The level of static electricity on your
body
is high enough to destroy the inputs of a CMOS device if you touch its

pins

with your fingers."


Basically irrelevant garbage, i could handle a million circuit board
without
causing any damage.

I can too. It isn't 'fingers', it's whether your body has built up an
electrostatic charge and then you touch one.

Semiconductors, nowadays, also include protective devices inside them to
reduce the chances of ESD damage. that doesn't mean they're 'immune' from
it and it still proves the point of voltage causing damage.

A case of a little knowledge incorrectly applied.

An excellent description of yourself.


I have also worked in enviroments where there are dozen's upon
dozens of computers, no surge protection and no failed computers.

Which you think 'proves' what?

My point.

Which would be what?


I get the feeling that someone here is trying to shift a job lot of

surge

protectors on ebay, either that or having a larf.

Think I will go and take a look

Have fun.


I will

Didn't find anything, did ya? chuckle

I looked elsewhere and there were plenty of other crooks flogging
"untested" items. " A customer probably returned this fully functioning
disk drive worth £20 out of the kindness of his heart."

half_pint wrote:

They are not delicate structures, no more than a grain of sand is

delicate.

Got that bit of information from a voo-doo doll, no doubt.


You think a voo-doo doll would withstand being heated to say 700 degrees?

I doubt it but then I'm not in the habit of consulting voo-doo like you
seem to be.

A zener diode, works by 'breaking down'. however it is not damaged

In a previous post you made a comment about 'a little knowledge

incorrectly

applied' and that is a beautiful example.


An example of you and your kind.

chuckle

You do know sand is mainly silicon?

Sure do. I also know a semiconductor isn't 'just sand'.

Try melting some sand some time, let me know how you get on.

We aren't talking about sand. We're talking about semiconductors.

permanently it still will work as a normal diode with in its limits.

there

is no permanent change in its functionality.

And nothing breaks down anyway it is normal operation at such vooltages.

MOSFET gate breakdown is not recoverable.

http://www.americanmicrosemi.com/tutorials/mosfets.htm

"breakdown voltage in MOS devices do not depend upon p-n junction stress
but rather upon the thickness and quality of the insulating oxide. When
breakdown does occur, the oxide is punctured and the device is destroyed."


I will get back on that tomorrow. your talking about break down of an
insulator anyhow,
not the silicon device.

Yes, the gate insulation, which is REQUIRED for the 'silicon device' to
freaking WORK.

half_pint wrote:

In the case of junction semiconductor devices the failure mode is most
commonly current heating of the junction and the problem with too much
voltage, in those case, is it causes excess current to flow. Same, but
worse, for reverse voltage as junctions that shouldn't conduct do, and

vice

versa, which scrambles what the circuit is designed for (bias points are
nonsensical, current flows where it wasn't supposed to, etc.), causing
excessive junction currents and, hence, temperature.

'Electronics', as a generic term, is complex and composed of many device
type and process. And there are many different failure mechanisms,
depending on what kind of devices are being used.

Even the generic term "transistor" doesn't clarify whether it's a bipolar
junction transistor, or a "Field Effect Transistor" (FET), or MOSFET, or
another.

http://www.semiconfareast.com/fmechs_die.html

Even that article doesn't cover everything.

MOSFETs, which are sensitive destructive breakdown from excessive voltage,
are the most common device technology used in PCs.

An amusing story about the first days of FET transistor production
illustrates the problem. Before they realized just how vulnerable the
devices were the failure rates were astronomical, in every sense of the
word. Some PCB manufacturers could get a single board with the things on
them to work. ALL had failures.

The problem was the devices had no static protection in them and things
like conductive foam/tube carriers hadn't been though of yet (what for,
eh?). They typically came 'plugged' into a block of plain old styrofoam
and, as it turned out, the simple act of pulling them back off created
enough static electricity to destroy them.

One manufacturer, before the 'secret' was fleshed out, got so fed up with
the 'out of box' unreliability (100% board failure) that they decided to
pre test the FETs before insertion. So they constructed a device test bed
and sat a fellow down to check them one by one.

The procedure ended up being: pull device from foam block, insert into

test

fixture, observe device is bad, throw device away." Not a single one
passed! (for the now obvious reason)

That test ended up being instrumental in finding the problem, however, as
the device manufacturer, in response to these 'claims' of failure (sure
pal), had already implemented a "100% device test" (so it can't be)...
before inserting them into the foam block, of course.


You describe a particticular circumstance where a large voltage

And how did you determine just how 'large' that voltage was?

It won't get any larger than needed to pop the device because, at that
point, the device conducts.

is
induces on the device and is earthed by the technician so a large
current will flow.

No. It's the voltage which does it (and the current is quite minuscule)

Just as if you take a flat pane of glass, horizontally suspended from the
ends, and place a brick in the middle. Everything is fine. You place
another brick onto the first. It holds. Then another brick, and another
until, eventually, the potential energy from the brick weight is too much,
the glass gives way, and they fall through.

It is the voltage potential, as with the potential energy from the weight
of the bricks, which causes the gate insulation to give way, as did the
glass. And then current flows through the failed gate, just as the bricks
flowed through the glass when it gave way.

When the devices are in a circuit board the situation is different and it
is more likey any charge will find a safer way to disapate

I never said otherwise. That doesn't mean voltage transients can't get in
there and cause damage.

It doesn't take much voltage to pop an integrated MOS device.

( they are
probably
designed in such a manner now any how).

It is nigh onto impossible to make every 'circuit' invincible and much more
practical to clamp surges so they don't get IN to the more sensitive circuits.

Personaly I cannot recall a cuircuit ever being damaged by static.

I dare say there are lots of things in the world you haven't 'personally'
witnessed.

Few things will survice several thousand volts going through them
for more than a fraction of a second.

Well, we're making progress then.

Except that "volts" don't 'go through'. Voltage is a potential between
points. It's current that 'goes through'.

half_pint wrote:

"David Maynard" wrote in message
...
=20
half_pint wrote:


"David Maynard" wrote in message
...


half_pint wrote:



But electronic devices are not connected directly to the mains the=
y
are connected to a power supply which is *designed* to copy
with large cueernts.

I suppose you think that means something but it's irrelevant to the=


point


that electronic devices react to electrical faults hundreds of time=
s

faster



than any fuse can. More to the point, any current that could possib=
ly

blow


a fuse is the RESULT of a failure which, by definition, means the f=
use
cannot 'protect' from it as it's already happened.


No we are talking about a surge in current from outside the house

No, we're talking about a voltage surge.


Voltage never causes device failure,

Research it and learn, or remain ignorant. Your choice.
=20
=20
Shut up.

How elegant.


so to speak. That surge must go through the fuse first, strictly

speaking,


well, at leaaast at the same time anyway.

There will be no current unless something conducts.


Brilliant!!!



I.E. If there were no devices plugged in (or wired in) the only effec=
t
would be a voltage spike on the interior power lines, but no current
=20
flow
=20
per see (besides leakage).


And no current flow =3D no damage.

Research electrostatic breakdown in semiconductors.
=20
=20
Post graduate research you mean?

Better to start a little more fundamental.

A simple web search will provide plenty of sources.

If, however, a susceptible device is connected to the power line and =
the
voltage spike is sufficient to cause electrical breakdown then the
=20
device
=20
fails and may pull excessive current as a result of the failure, whic=
h,
=20
if
=20
severe enough, will blow the fuse. But the failure has already occurr=
ed
=20
by
=20
the time the fuse sees anything, much less blows.


Only current flow causes damage,

false.


current flow blows fuses.

true
=20
=20
heat strictly speaking.

True enough.

A main spike hits the robust components of the PSU first

I suppose you want to ignore modem lines.
=20
I dont connect my comms line to the mains.

Good thinking.

Figuring that makes them, and the computer, safe from surges isn't good=20
thinking.

these are not sensitive to high voltages,

Depends on how high the voltage.


infact the voltages inside
them are dangerous to humans,

Some are; others aren't.

The fact of the matter is that you know nothing of which you speak.
=20
********.
=20

I feel the same way.


OK if you connect one leg of your 3GHz pentuim to the
mains live connection and the other leg to earth you will probably=


damage it



but I am not recommending that.





And it's inherent to the nature of electronics.
By the time an electronic device is pulling excessive current
=20
whatever
=20
is



at fault inside has long since gone to the happy hunting grounds,=
or

else



it would not be pulling excessive current. And there's nothing yo=
u
=20
can
=20
do



about it by 'sizing' the external fuse as the failed device could=
be
=20
a
=20
100mw component inside a 200 watt computer where the normal
=20
operating
=20
power




fluctuations are hundreds of times larger.



I dount there are many 100mw components in a PS and even if there
were and they did blow they would protect your computer.

For that to even begin to make sense you'd first have to consider a=


blown


power supply as the device still 'working', but I doubt most people=

=20
do.
=20
Further, I have no idea what makes you think a 'blown' component in=

=20
the
=20
PSU



will 'protect' the computer. All one need imagine is the reference

voltage


zener blowing, resulting in lord knows what voltage being thrown in=
to

the


system and destroying massive numbers of components.


A zener diode is already 'blown' so to speak, thats how they work.

No, it isn't.



The voltage across them is basically the same whatever the input

voltage.


An obvious contradiction, as stated.


Rubbish that is how they are designed to work!!

There cannot be "whatever the input voltage" to the one and only device=
in
your statement, the zener, if it's "the same."



A zener conducts when the voltage across it reaches a certain level,
otherwise is does not conduct, and the source better be current limit=
ed,
most commonly by a series resistor, or else the zener will self
=20
destruct.
=20
In that case, by over heating.


Ans of course they are always current limited by a series resirtor in
appliances.

Well, no. That just happens to be the cheapest and most common means wh=
en
they're used as a simple voltage reference. It is not the only way they=
're
used.



Essentially it is a grain of sand,

Not hardly.


I am afraid it is.

You apparently haven't a clue.
=20
sure

The oxide gate insulation of MOS devices that we just talked about, for o=
ne=20
obvious example.


It's like saying silicone is 'essentially sand', and has the properties=
of
sand. Or that glass is 'essentially sand', and has the properties of sa=
nd.

One has to go back to before even the days of alchemy to find such
absurdities promulgated as 'knowledge'.


its not going to melt,

'Melting' has nothing to do with it.

What?

Simple enough statement.


at least not
before
other metal components vapourise. And the first component to vapouri=
se
will be the fuse in the plug, you can be sure of that.

No offense but you really don't understand semi-conductors at all.


You are maing no sense ar all.

That's probably how a medieval alchemist would feel about a discussion =
on
quantum mechanics, and for the same reason.
=20
=20
Are you on drugs?

Not yet, but you're giving me a headache so an aspirin might be in order =
soon.


That is, of course,
why all decent PSUs include over voltage protection on the power
=20
rails.
=20

Ah hah!!




And
while you may gleefully scream "ah hah!," as if that means somethin=
g
=20
to
=20
your case, it isn't done with fuses because fuses are too slow to

protect


electronic components.


I think you will find 99% of surge protectors contain a fuse, which =
is
=20
a
=20
bit


odd really if they are surplus to requirements?

No one ever said they were 'surplus'. The problem is you don't
=20
understand
=20
the nature of electronics and the purpose of various protection devic=
es.


I do

It is obvious you don't and what's further obvious is that you refuse t=
o
learn a thing about it.


A fuse blows on a sustained current fault and breaks the connection: =
a
preferable situation to continuing to draw fault current because, for=

=20
one,
=20
it prevents fires.

That has nothing to do with 'protecting' what is already a damaged
=20
device
=20
causing the current fault.


You don't really understand electricity do you?

I have already provided you with corroborating authoritative sources fo=
r
=20
my
=20
explanations.

I challenge you to provide one for your absurd contention that voltage
cannot damage semiconductors.
=20
=20
If I have a billion volts at one end of a 1mA wire fuse and a billion v=
olts
at the
other end will it blow?

We aren't talking about devices with 0 voltage across them so your questi=
on=20
is supercilious, at best.


The issue isn't 'where' the fault occurs in the device but that a f=
use
simply cannot 'protect' from it (voltage induced failure).




However before it did blow it would probably required a
several fold increase in current for a substained period which
would obviously blow the fuse first.

This is where you are sorely mistaken as you seem to think that the=

=20
only
=20
way any device, of any kind, fails is by current induced heating bu=
t

that


is simply not the case with electronic devices. Too much voltage, a=
s
perhaps induced by a surge, will instantly destroy semi-conductor
components; after which they may simply do nothing or, more common,=

=20
draw
=20
excessive current. At which point, anything a 'fuse' detects is lon=
g

since


after the fact.

No that current has to come in via the fuse which is designed to fai=
l
=20
as
=20
quickly
as possible, as opposed to other components which are designed *not*=
to
fail.

You're never going to understand it till you get it out of your head
=20
that
=20
'excessive current' is the only thing that damages semi-conductors.


Heat is the only souce of damage, and current not voltage
produces heat.

Wrong, and I've provided authoritative sources to corroborate it.
=20
Garbage.

Are you blind too, or is it that you just don't read?


(Heat can destroy them too but that isn't the mode we're talking ab=
out

with



surge protection)




And if you are saying that semi conductor devices are inherently
sensitive to current then obviously we would make fuses out of the=
m.

It is your mistaken notion that only 'current' causes failure that
=20
leads
=20
you to invalid assumptions.


But I am right of course, *only* current *ever* causes electrical

failures.


A semiconductor device, or any electrical device will work quite

happilly


a 1 billion volts.

Surely you jest.

Why in the word do you think power supplies, much less multi-voltage

units,


even exist if electronics works 'quite happily' at just any old volta=
ge?

I think you missed the point.

If you thought so that certainly doesn't elaborate, but don't bother as=

I've had enough of your absurdities anyway.
=20
I explained above, voltage is relative,

What you described above was a device with no voltage potential across it=
=20
but that has no value whatsoever to the matter of surges, which are large=
=20
potentials across the device.

It is, however, how you got your so called 'static shock' from the car=20
radio without it being damaged.

However semiconductors are make out of silicone which has
an extremly high melting point.

Which is irrelevant because that is not what causes device failure.=



Heat is the only cause of device failure. Ever. Period.

Just plain wrong.

Really now, even your own decryption, as misguided as it is, contradi=
cts
THAT absurdity because, if it were true, there would never ever be an=

electronic failure, unless someone shoved it inside a 900F oven. And
=20
that
=20
is clearly not the case.


You don't have to heat the whole device, the damage is usually localis=
ed

You actually stumbled onto something that's halfway correct:
=20
=20
Its all correct anad i didnt stumble I knew where I was going.

You 'know where you are going' like Columbus 'knew where he was going'. A=
nd=20
the natives have been called 'Indians' ever since.

you can have
localized heating. It's not, however, very relevant to the point becaus=
e
the thermal conductivity of semiconductors won't allow so dramatic a
difference, when compared to your claimed '900F' destruction point, as =
to
matter to the illustration. So we need fools shoving them into 700F ove=
ns,
instead of 900F ovens, before any device would ever fail. It is still a=
n
absurdity.

Btw, the melting point of silicon isn't 900F, it's (much) higher, but I=
'm
using your numbers to illustrate that even your own 'theory' is
=20
irrational.
=20
I know it is higher but some of the doping agents are lower so I
compromised. :O)

IC manufacturers don't seem to share your 'compromise', but it doesn't=20
really matter.

=20
(we are basically talking about
sand) indeed silicone has replaced asbestos as a safer heat
resistant material.
http://www.candochefs.com/silbakmat1.html

" Use in up to 900 degrees F! "

Obvioulsy fuses are *designed* to melt quickly
at low temperatures.

Semiconductors materials are probably never damaged
by heat, at least not untill long after the metalic contacts have=

vapourised.

'Melting' is not the failure mechanism of semi-conductor devices.


Yes it is.

No, it isn't. And I'd advise you to go learn something about
semi-conductors before you make such statements because they make it

rather


obvious you have no idea how they work.


I have every idea how they work, much more so than you.

Feel free to quote a text book, or some other authoritative source, tha=
t
supports your fantasies.
=20
I have a brain so I need no text books.

That would explain it.


And even if you did have a
'constant power consumption' electronic device, for which you cou=
ld
'tightly' size a fuse, electronic components can, and do, go into=

catastrophic failure hundreds of times faster than a fuse can blo=
w.

Surge -- component failure -- excessive current -- fuse blows





They blow before the device draws enough current to be damaged,
=20
that
=20
is


how they are designed.

That is certainly the myth. It is not, however, reality.


You don't have a huge backlog of expensive surge protectors to shi=
ft
by any chance?

I don't 'sell' anything nor is it any skin off my nose if your
=20
computer
=20
is


damaged because you think a fuse will 'protect' it.

Nice try buddy, uk.comp.vendors, pull the other one, I wasn't born
yesterday.

I'm posting from alt.comp.hardware.pc-homebuilt.




There of dozen of devices in my home which contain IC's none has eve=
r
failed due to a power surge, zilcho.

And you think that 'proves' what?

My point and my arguement, unsurprisingly.

Since you made no 'point' there is nothing it could.
=20
probably went over your head.

You first have to 'shoot' for there to be a trajectory.


There are also many IC's in my car which regularly gives me a big za=
p
=20
of
=20
static electricity, I can assure you that the shock has effected me =
far

more


than
my car stereo etc....

Oh, really? And what were you doing with the case to these devices op=
en
=20
so
=20
that you were getting a 'static discharge' from the 'ICs'?


Still a huge voltage surge and no anti - surge device yet MIRACULOUSLY=

ALL THOSE SENSITIVE DEVICES WERE TOTALLY UNDAMAGED
HOW STRANGE????????

Not at all. It has nothing to do with ICs being 'immune' from static
voltage damage but it's obviously useless to attempt educating you abou=
t
anything.
=20
=20
Its fact though.

I have no doubt you got a 'shock'. It's your 'who needs a textbook?'=20
analysis of what it means that's cockeyed.

=20
But since you bring it up you could expand your horizons by doing a w=
eb
search on ICs and static electricity and, in particular, ESD protecti=
on.


Already have, not that I needed to, everything I found bacjed my
case.

ROTFLMAO


Here's one to get you started:
http://www.informit.com/articles/art...704&seqNum=3D3

"In general, MOS devices are sensitive to voltage spikes and
static-electricity discharges. This can cause many problems when you
=20
have
=20
to replace MOS devices, especially complementary-symmetry metal-oxide=

semiconductor (CMOS) devices. The level of static electricity on your=

=20
body
=20
is high enough to destroy the inputs of a CMOS device if you touch it=
s

pins


with your fingers."


Basically irrelevant garbage, i could handle a million circuit board
without
causing any damage.

I can too. It isn't 'fingers', it's whether your body has built up an
electrostatic charge and then you touch one.

Semiconductors, nowadays, also include protective devices inside them t=
o
reduce the chances of ESD damage. that doesn't mean they're 'immune' fr=
om
it and it still proves the point of voltage causing damage.


A case of a little knowledge incorrectly applied.

An excellent description of yourself.



I have also worked in enviroments where there are dozen's upon
dozens of computers, no surge protection and no failed computers.

Which you think 'proves' what?

My point.

Which would be what?



I get the feeling that someone here is trying to shift a job lot of

surge


protectors on ebay, either that or having a larf.

Think I will go and take a look

Have fun.


I will

Didn't find anything, did ya? chuckle
=20
=20
I looked elsewhere and there were plenty of other crooks flogging
"untested" items. " A customer probably returned this fully functioning=

disk drive worth =A320 out of the kindness of his heart."

wag, wag, babble, babble.

Someone wrote:

....
Newsgroups: uk.comp.vendors,uk.comp.homebuilt,alt.comp.hardwar e,alt.comp.hardware.pc-homebuilt
Subject: Are mains surge protectors needed in the UK?
Date: Sun, 11 Jul 2004

Lines: 856

Never mind surge protectors, let's go for the record!

In article , David Maynard
writes

Rather amazing, actually. I mean, even when one points to authoritative
sources he simply declares everyone else ignorant or just plain dumb.

Makes me wonder how people like that arrive at their 'beliefs'.

Voodoo? (grins, ducks & runs

--
A. Top posters.
Q. What's the most annoying thing on Usenet?

Mike Tomlinson wrote:

In article , David Maynard
writes


Rather amazing, actually. I mean, even when one points to authoritative
sources he simply declares everyone else ignorant or just plain dumb.

Makes me wonder how people like that arrive at their 'beliefs'.


Voodoo? (grins, ducks & runs


LOL

Novel idea

In article , w_tom
writes

Elsewhere in this topic is a claim that fuses can prevent
surge damage.

That's half_pint's claim, not mine, and is the subject of a separate
subthread. Please stick to the discussion in hand. Diversion is a
classic tactic employed by those losing an argument.

So we ask the MOV professionals to define "degraded". From
a Littelfuse application note AN9310:
A failed device is defined by a ±10% change in the
nominal varistor voltage at the 1mA point.

I suggest you consult a dictionary or attend that remedial reading
class. You'll see there is a difference between "degraded" and failed".

This latter mode of stress may result in the eventual
open-circuiting of the device due to melting of the
lead solder joint.

And what is required to melt that joint? That's right, heat. By the
time this has happened, the thermal fuse has opened and taken the device
out of circuit - before it has had a chance to vaporize.

To meet the human safety requirements imposed by UL1449 2nd
edition, manufacturers install a thermal link as demonstrated
in a schematic from Mike Tomlinson. When does that thermal
link open? When the MOV is degraded? Of course not.

Liar. When MOVs degrade, they heat up. This is clearly demonstrated by
the pictures in the link you posted:
http://www.zerosurge.com/HTML/movs.html

The thermal fuse in the design then takes the MOV out of circuit before
it can fail catastrophically.

He even provided a schematic to show us the thermal link that
blows when MOV degrades!

Yes, I did, didn't I? Instead of waving my hands around and getting
hysterical like you.

A 330 volt MOV degraded so that it operates at 300 volts or
360 volts will blow the thermal fuse? Of course not.

Of course it will, idiot. It'll heat up. Now go and look at the specs
of thermal fuses on the web.

As
demonstrated in a scary picture from Zerosurge, the MOVs can
even be removed and the indicator lamp says protector works
"OK":

Like I said earlier, those are cheap and nasty protectors made for the
American market, posted by a manufacturer with a vested interest in
denigrating the competition so they can sell their own, allegedly
superior, products.

Aa degraded MOV
will not open (blow) the thermal disconnect device LK1. But a
catastrophically failed (short circuited) MOV will.

Wrong.
From http://powerelectronics.com/mag/powe...rotected_movs/

"If an MOV is subjected to a sustained abnormal overvoltage, limited
current condition (as required in UL1449), the MOV may go into thermal
runaway, resulting in overheating, smoke, and potentially fire. For end
products to comply with UL1449, the MOV must have some level of
protection to prevent this failure mode. That protection has
traditionally been a thermal fuse or thermal cutoff (TCO) device."

gasp! What do you think LK1 is in the diagram I posted?

Lets
remember those numbers posted up to.

Your reliance on "numbers", rather than common sense, brings to mind the
old adage "there's lies, damn lies, and statistics." Whoever said that
must have had you in mind.

Surges are microsecond
events. If they damage the MOV, then milliseconds of AC
electric cause the thermal link to fail.

Wrong. MOVs gradually degrade with each surge they pass. You've even
stated this in another post. As they degrade, they heat up. At some
point, they will heat up enough for the thermal fuse to open, taking
them out of the circuit BEFORE they can explode violently.

But a grossly
undersized MOV short circuits.

Prove that the MOVs in the circuit I posted are "grossly undersized" for
their intended application, please.

Milliseconds later, AC
electric heats that damaged MOV,

gasp He understands!

pushes too much current to
blow that thermal link, and illuminates that warning light
LP1.

Exactly!

You've just totally contradicted yourself.

A surge protector is only as effective as its earth ground.
Facts that don't change no matter what fancy lights report and
no matter how Mike Tomlinson insults others.

yawn I only insult liars and idiots. Your posts prove beyond a
shadow of a doubt that you're a member of that august group.

HTH. HAND. FOAD.

--
A. Top posters.
Q. What's the most annoying thing on Usenet?

GDTs and MOVs are paired both for faster response time and
for the lower conductive voltage provided by a GDT. However
GDTs alone were fast enough. At £2 or $3 per GDT, then GDTs
also are too expensive. MOVs wholesale on the order of $0.10
each. Which is more profitable when even a 160 joule UPS is
considered by consumers to be more than sufficient protection?

If they were trying to make a faster and superior protector,
then MOVs would instead be replaced by avalanche diodes that
are faster, do not degrade as MOVs do, and can shunt at a
lower threshold voltage. But again, avalanche diodes cost
closer to $1. Also too expensive when selling plug-in
protectors only for the massive profits.

Jonathan Buzzard wrote:
On Sun, 11 Jul 2004 17:38:04 -0400, w_tom wrote:
[SNIP]
An MOV does not get hotter only because its let-through
voltage changes; is below 300 volts or above 360 volts. Lets
remember those numbers posted up to. Surges are microsecond
events. If they damage the MOV, then milliseconds of AC
electric cause the thermal link to fail. But a grossly
undersized MOV short circuits. Milliseconds later, AC
electric heats that damaged MOV, pushes too much current to
blow that thermal link, and illuminates that warning light
LP1.

You are forgetting the GDT w_tom I know you don't like
them, but they are cheap, and they are fitted to surge
protectors. As a result the MOV only has to be good enough
to deflect the leading edge of the surge till the GDT takes
over to deflect the bulk of the energy in the surge.

half_pint wrote:

[...]

The only dead transistor I have came across had a big hole melted in the
middle of its casing.

Yes, you sometimes find a round hole in a medium power transistor, that's for
attaching it to a small heat sink! I thinking you're winding us all up.