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lightning protection

H

Halfgaar

Jan 1, 1970
0
I don't know about your particular case, but I tend to view these as
paying for the insurance not surge protection. Given that most power in
UK cities comes in underground I am extremely dubious about the value
of these devices in my enviroment. I would rather pay for better quality
plugs, sockets and cable.

Where I come from, all cables are underground as well, but what about surges
from electronics and welding machines nearby?
I have seen one of these fail to protect its load, turned out the
"electrician" had wired up between the red & blue busbars (across
2 phases of a 3 phase line) and stuck 400V at practically unlimited
current up an alegedly 240V feed. The smoke was impressive.

Well, continuous 400V is not exactly a surge. A surge is usually hunders of
volts, as I understand it.
Regards, Dan.

Halfgaar
 
T

tube2ic

Jan 1, 1970
0
Hi Halfgaar,

Don't waste your breath on this guy. At first I thought he was
genuinely trying to help you and had just got a few facts mixed up.
But a quick search on google groups for w_tom soon convinced me this
guy is a crock. He even got told off by some ladies at alt.sewing for
some drivel about unplugging their sewing machines during a storm and
the same drivel about whole house protectors and 10 ft grounds. To
cut a long story short, I think that this guy got his brains zapped in
due to lightning. Probably because he forgot to ground himself by
sticking a 10ft grounding rod up his backside.

It is not my nature to be offensive to anyone but this guy w_tom is
the limit. He is the epitome of everything that is bad about the
internet and newsgroups. Unreliable information that sounds just about
right to convince a layman while having no accountability for his
actions coupled with sheer volume of rubbish text and complete
disregard for the relevance of his drivel to the thread. I have yet to
see him actually answer a question!

-Tube2ic-
 
H

Halfgaar

Jan 1, 1970
0
tube2ic said:
Hi Halfgaar,

Don't waste your breath on this guy. At first I thought he was
genuinely trying to help you and had just got a few facts mixed up.
But a quick search on google groups for w_tom soon convinced me this
guy is a crock. He even got told off by some ladies at alt.sewing for
some drivel about unplugging their sewing machines during a storm and
the same drivel about whole house protectors and 10 ft grounds. To
cut a long story short, I think that this guy got his brains zapped in
due to lightning. Probably because he forgot to ground himself by
sticking a 10ft grounding rod up his backside.

It is not my nature to be offensive to anyone but this guy w_tom is
the limit. He is the epitome of everything that is bad about the
internet and newsgroups. Unreliable information that sounds just about
right to convince a layman while having no accountability for his
actions coupled with sheer volume of rubbish text and complete
disregard for the relevance of his drivel to the thread. I have yet to
see him actually answer a question!

-Tube2ic-

From my point of view, you could easily be the one telling lies :). But fear
not, my gut already told me to trust you more then him.

BTW, just to let you know: The voltage over phase and neutral is 226 here.
The voltage over phase and ground is 226. That falls within the 2 volt
limit, wouldn't you agree :)?

Anyway, thanks for the warning.

Halfgaar
 
useless to earth borne wire surges IF not using the single point earth
ground concept. And better quality plugs, sockets, and cable would
not help.

Granted they do not help with surge protection, but in terms of increased
system reliability for a given amount of investment the case is not
anything like so clear.

Regards, Dan.
 
T

tube2ic

Jan 1, 1970
0
From my point of view, you could easily be the one telling lies :).

Yes! Unfortunately that is the way of the newsgroup :)
But fear not, my gut already told me to trust you more then him.

You have a smart gut there Halfgaar feed him a beer from me:)
BTW, just to let you know: The voltage over phase and neutral is 226 here.
The voltage over phase and ground is 226. That falls within the 2 volt
limit, wouldn't you agree :)?

Yes that is fine. In many countries the neutral is actually tied to
ground at a particular tie point and so there would be no difference
in voltages unless you are very far from that tie point between
neutral and ground. The tie point could be the transformer, the pole
or your utility meter, depending on the regulation for your country.
This is the reason I said a two-pin surge protector is also possible
provided that it was originally designed for two-pin operation.

------------------------------------
Another common problem that could cause damage to electronic equipment
and cause protection mechanisms to work incorrectly is the transposing
of phase and neutral at the socket. I don't know what is the standard
in your country but you should spend a few minutes checking this.
Typically the molded plugs on some appliances display this and that
may be a good starting point to verify.
If a surge protector was designed with only one shunt element between
phase and ground then plugging in such a protector into a transposed
socket would actually put the shunt element between neutral and ground
which is at the same potential and therefore would be no protection at
all. Better quality protectors have two shunt elements between each
line to ground pin.

-tube2ic
 
T

tube2ic

Jan 1, 1970
0
Where I come from, all cables are underground as well, but what about surges
from electronics and welding machines nearby?
In case of indirect lightning strikes, it does not matter whether the
cable is underground. The energy is still picked up by induction.The shunt element in the protector is designed to fire at anywhere
between 260 to 700 volts depending on the design. It is also not
capable of contiuously shunting energy when fired. Hence a good
protector should have a series fast acting fuse which will blow as
soon as the shunt element fires and shorts out the AC mains. Otherwise
the protector will be destroyed. (Note that the fuse is really not
much help for lightning protection and it's purpose is to protect the
protector in similar situations as above e.g. if a high voltage line
fell on a utility mains wire)
Halfgaar you mentioned about the overload breaker on your protector.
If the overload breaker is wired before the surge supressor, then it
will also perform a similar function as described above. If the
overload breaker is behind the surge supressor then its primary
function will be what I already described earlier.
Well, continuous 400V is not exactly a surge. A surge is usually hunders of
volts, as I understand it.
A surge is any voltage above normal. when a surge lasts for a longer
duration, it may sometimes be called a swell. However, your case was
that of incorrect wiring and not really a surge on a normal line.
 
H

Halfgaar

Jan 1, 1970
0
tube2ic said:
Halfgaar you mentioned about the overload breaker on your protector.
If the overload breaker is wired before the surge supressor, then it
will also perform a similar function as described above. If the
overload breaker is behind the surge supressor then its primary
function will be what I already described earlier.

Well, to find that out, I have to open it up. It at least is psysicly
closest to the powerinlet, so I would guess the power goes trough that one
first.

Halfgaar
 
T

tube2ic

Jan 1, 1970
0
I don't know about other countries, but here you can plug in a plug two
ways, so I would suspect that surgeprotectors meant for use here, are
designed with more than one shunt element.
I would not assume that. It is a simple matter to open it and check.
That way you will be absolutely certain.
BTW, something I was still wondering: When a surge is shunted, does that
mean that power is interrupted for a very short time?

The typical devices used as shunting element are voltage sensitive.
This means that at normal voltage they are very high impedance (Open
circuit). When a surge reaches the voltage at which the device
activates, the device goes into low impedance state (short circuit).
As soon as the voltage drops to normal, the device stops conducting
and goes back into open circuit state. This clamps the voltage at the
firing voltage of the device during a fault condition. Now if there is
a fuse or breaker and the surge is long enough in duration, the shunt
element (which is actually shorting your AC mains) will cause enough
current to flow that will cause the fuse to blow or breaker to trip
and thus interrupt the supply and protect the shunt element. If the
surge is short duration, the short is momentary and does not blow the
fuse or trip the breaker. (This is because a fuse or breaker responds
relatively slowly to the fault condition) so all that will happen is
that the voltage clamps to the firing voltage of the shunt element.
(And you will hear horrible farts in your stereo system :)
Sometimes people replace the fuse with one of a wrong rating or
response time (Or there isn't a fuse) and this results in spectacular
fireworks as the shunt device is destroyed due to the high currents
flowing through it.

I also found a website that explains surge protectors in fairly simple
terms (No numbers to satiate our friend w_tom :) but should do well
for you)
http://computer.howstuffworks.com/surge-protector.htm
The explanation is fairly simplistic in that it assumes a number of
things but it give a good enough picture of what goes on inside the
protector.

-tube2ic-
 
T

tube2ic

Jan 1, 1970
0
In the previous post, where I describe the destruction of the shunt
element due to wrong or no fuse, I want to clarify that this happens
for the longer duration surges that allow enough current to flow that
is lethal to the shunt element.
 
H

Halfgaar

Jan 1, 1970
0
tube2ic said:
I would not assume that. It is a simple matter to open it and check.
That way you will be absolutely certain.

And how exactly do I identify a shunt element? How can I see if there are
more? If it's connected two phase, neutral and ground, does that mean it's
OK?

I'll think I'll open it tonight, after I've shut down all my equipment, and
have a look. A while back, you also gave me a description of what a
reasonable surgeprotector would look like, I still have to check that out.
The typical devices used as shunting element are voltage sensitive.
This means that at normal voltage they are very high impedance (Open
circuit). When a surge reaches the voltage at which the device
activates, the device goes into low impedance state (short circuit).
As soon as the voltage drops to normal, the device stops conducting
and goes back into open circuit state. This clamps the voltage at the
firing voltage of the device during a fault condition. Now if there is
a fuse or breaker and the surge is long enough in duration, the shunt
element (which is actually shorting your AC mains) will cause enough
current to flow that will cause the fuse to blow or breaker to trip
and thus interrupt the supply and protect the shunt element. If the
surge is short duration, the short is momentary and does not blow the
fuse or trip the breaker. (This is because a fuse or breaker responds
relatively slowly to the fault condition) so all that will happen is
that the voltage clamps to the firing voltage of the shunt element.
(And you will hear horrible farts in your stereo system :)
Sometimes people replace the fuse with one of a wrong rating or
response time (Or there isn't a fuse) and this results in spectacular
fireworks as the shunt device is destroyed due to the high currents
flowing through it.

Won't the short powerinteruption be destructive to the devices connected to
it? My monitor for example won't power on immediatly when you turn it on
after you've switched it off. You have to wait a few seconds, it's for
protection.
I also found a website that explains surge protectors in fairly simple
terms (No numbers to satiate our friend w_tom :) but should do well
for you)
http://computer.howstuffworks.com/surge-protector.htm
The explanation is fairly simplistic in that it assumes a number of
things but it give a good enough picture of what goes on inside the
protector.

Now why didn't I think of that. I know of the howstuffworks website. Thanks,
I'll take a look at it.
In the previous post, where I describe the destruction of the shunt
element due to wrong or no fuse, I want to clarify that this happens
for the longer duration surges that allow enough current to flow that
is lethal to the shunt element.

I gathered as much.

Halfgaar
 
H

Halfgaar

Jan 1, 1970
0
I did some checking. My surgeprotector looks like this: It has three parts
that look like caps (do you think they're the two caps and the MOV?), 2
fuses, a light and a component I can't identify. Phase, neutral and ground
are all connected to it. There's no common mode choke (what does it do? Is
that part of line conditioning?).

I've also got some questions:
- In the howstuffworks article, it said that a electromagnet-like part is
used for lineconditioning. Is line conditioning probably the thing I need
to eliminate clicks and plops in my amplifier?
- my surgeprotector has a clamping voltage of 750 volt. The article said
higher than 400 is junk. Does this mean mine is junk? I mean, is higher
than 400 V perhaps only too high for 120V power grid? The powergrid here is
230V.
- Mine doesn't have an UL rating, no energy absorption specs, no response
specs. Are those bad signs?
- The PDF you linked a few replies back, said that surgeprotection on the
powerline and not the phone and the cable is just a good as no protection.
Are there seperate phone and cable protectors? And do cableprotectors
decrease signalstrength?

I guess the main thing I'd like to know is whether or not my surgeprotector
is adequete.

Halfgaar
 
T

tube2ic

Jan 1, 1970
0
I did some checking. My surgeprotector looks like this: It has three parts
that look like caps (do you think they're the two caps and the MOV?), 2
fuses, a light and a component I can't identify. Phase, neutral and ground
are all connected to it. There's no common mode choke (what does it do? Is
that part of line conditioning?).
If they all look alike they probably are all MOV's. But, it's is hard
to tell with just what you describe. They could be 2 MOV's and 1 CAP
for all I know. Can you transcribe the markings? It would give me some
clue. Also try to describe what is connected to what. Is it connected
like a triangle with each device the side of the traingle and the
corners the three AC wires? (That description sounds terrible but you
get my drift? :)
Can you describe the component that you can't identify?
The common-mode choke is part of line-conditioning which you
apparently don't have.
I've also got some questions:
- In the howstuffworks article, it said that a electromagnet-like part is
used for lineconditioning. Is line conditioning probably the thing I need
to eliminate clicks and plops in my amplifier?
Yes. The electromagnet-like part is your common-mode choke.
- my surgeprotector has a clamping voltage of 750 volt. The article said
higher than 400 is junk. Does this mean mine is junk? I mean, is higher
than 400 V perhaps only too high for 120V power grid? The powergrid here is
230V.
I do not have a standard answer to this question. It depends on the
design. It will definitely be higher than the number for 120V. On the
other hand, 400V is roughly 3 times the 120V line. By that yardstick,
750V sounds about right for 230V. I don't normally design AC mains
suppressors and work mainly on the telephone and data side so I do not
have design data to give you an authoritative answer on this one.
- Mine doesn't have an UL rating, no energy absorption specs, no response
specs. Are those bad signs?
Not neccessarilly. Some countries are gung ho about ratings for
everything (eg Marketing driven societies) Some are more laid back. It
definitely helps if you do have a rating as that gives you an
indication that the design was verified to conform to the rating.
- The PDF you linked a few replies back, said that surgeprotection on the
powerline and not the phone and the cable is just a good as no protection.
Are there seperate phone and cable protectors? And do cableprotectors
decrease signalstrength?
That statement applies only to two-link connections, where the
appliance is connected to both AC mains and telephone(modem) such as a
PC or a TV Set-top box that is connected to cable and to AC mains.
I would say that the statement is probably quite true.
Cable protectors (I presume you mean for cable TV) do attenuate signal
if they are not built for the application. Always use recommended
equipment on cable and telephone networks. On telephone networks,
dial-up modems are more forgiving than xDSL. Always use a protector
that is designed for the application. Also it is not a matter of
simply hooking up protection to every wire that enters the equipment
being protected. You need to tie all the grounds of these equipment
together at one point to the power ground for the surge protection to
be properly effective. You often get a powerstrip with all the
protection included for a PC or the UPS has it built in. But I
suispect that those were designed with dial-up moodems in mind and not
xDSL.
I guess the main thing I'd like to know is whether or not my surgeprotector
is adequete.
It is very hard to tell Halfgaar. It probably is but you probably
should not expect a more definite answer from a newsgroup.
Vinay
 
T

tube2ic

Jan 1, 1970
0
What would the cap be part of? Is it possible it's designed without a cap? I
can only open up the powerstrip on the end, so I can hardly see the
components let alone what's written on them. I could see the part I
couldn't identify. I should have written down what it said, but I remember
something like "xxx k" (132k for example). The thing that I would think of
would be a resistor, but it doesn't look like it at all. It's more like
those plastic bags of blood.... A blown-up rectangular cube...
And because I can hardly see the device, I also can't see how it's
connected.
A resistor is usually in series and is much lower in value (upto a few
hundred ohms only) It is sometimes used in lieu of an series inductor
as it is cheaper.
I have a dial-up modem, but maybe sometime I'll have xDSL. BTW, I should use
a protector that is designed for the application? Does that mean a dial-up
modem requires a different protector than an xDSL modem?
Modems work at frequencies higher than those used by a telephone. An
xDSL modem uses higher frequencies than dial-up modems. The shunt
elements in the surge suppressors can attenuate the signal at higher
frequencies because they have parasitic capacitance. A surge protector
designed for xDSL would be designed not to attenuate the signal.
The thing I need then is an AC protector with phone and cable integrated,
since my VCR and computer are both connected to the TV cable and the
phoneline and the VCR are connected to the computer. And the radiocable
enters my receiver, which in turn is connected to AC, the computer and the
VCR...
Good Luck! I have never seen one with all the protectors rolled in one
yet.

-Tube2ic-
 
H

Halfgaar

Jan 1, 1970
0
Thanx for all the info. I think I know enough (well, for now at least :)).

Halfgaar
 

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