MOVs and surge suppressors

[[email protected]]

Many surge suppressors on the market (I'm only talking about the MOV
type here, not the fancy induction style) have little indicator lights
to tell you if the thing is still providing protection. How do they
do this? I thought the only way to test a MOV was to send a surge
through it, and then you will only know what condition it was in
before you sent in the surge. What is the circuit diagram for one of
these indicator LEDs, and is this a way to test any MOV or MOV device?

Thanks.

 

[Phil Allison]

Many surge suppressors on the market (I'm only talking about the MOV
type here, not the fancy induction style) have little indicator lights
to tell you if the thing is still providing protection. How do they
do this?

** There is a fuse wire link in series with the MOV.

If the MOV blows all to hell, then so does the fuse.

The light ( usually neon ) indicates that the fuse is blown.



........... Phil

 

[Rich Grise]

Many surge suppressors on the market (I'm only talking about the MOV
type here, not the fancy induction style) have little indicator lights
to tell you if the thing is still providing protection. How do they
do this? I thought the only way to test a MOV was to send a surge
through it, and then you will only know what condition it was in
before you sent in the surge. What is the circuit diagram for one of
these indicator LEDs, and is this a way to test any MOV or MOV device?

You're right, there's no way to test an MOV, and any indicator that
claims to indicate the status of the MOV is nothing but marketing hype.

Cheers!
Rich

 

[Paul E. Schoen]

You're right, there's no way to test an MOV, and any indicator that
claims to indicate the status of the MOV is nothing but marketing hype.

Cheers!
Rich

A typical MOV has a capacitance of 100-2000 pF, which is an impedance of
about 1.3 - 26 Megohms at 60 Hz. This is barely enough to light a neon lamp
at 120 VAC. But it could provide enough current to drive a transistor and
indicator lamp. However, a failing MOV gradually increases its leakage, and
it would take a sophisticated circuit to analyze that.

I think Phil is right, except that the indicator is probably across the
MOV, so it lights if the fuse is OK. I know *my* surge suppressor has a
green light that indicates "protection", so I think that's how it must
work. I don't really want to take it apart (unless it goes bad).

Paul

 

[ehsjr]

Many surge suppressors on the market (I'm only talking about the MOV
type here, not the fancy induction style) have little indicator lights
to tell you if the thing is still providing protection. How do they
do this? I thought the only way to test a MOV was to send a surge
through it, and then you will only know what condition it was in
before you sent in the surge. What is the circuit diagram for one of
these indicator LEDs, and is this a way to test any MOV or MOV device?

Thanks.

In some failures, the indicator light can indicate that the
MOV is bad, but it can never indicate that the MOV is good.
So if the light tells you it is bad, believe it. If the light
tells you the MOV is good, it could be lying to you.

Ed

 

[Phil Allison]

"Paul E. Schoen"

I think Phil is right, except that the indicator is probably across the
MOV, so it lights if the fuse is OK. I know *my* surge suppressor has a
green light that indicates "protection", so I think that's how it must
work. I don't really want to take it apart (unless it goes bad).

** The light can be made to work in the opposite sense - ie as a warning
the MOV has been damaged - by having a resistor ( say 50 kohms) across the
MOV and the neon plus 100 kohms wired across the fuse link.

This will operate the neon in both open and shorted MOV conditions, if the
link goes open.



........ Phil

 

[w_tom]

...
I thought the only way to test a MOV was to send a surge
through it, and then you will only know what condition it was in
before you sent in the surge. What is the circuit diagram for one of
these indicator LEDs, and is this a way to test any MOV or MOV device?

As others have noted, an MOV is 'protected' by a thermal fuse. If a
surge is so large as to cause MOV to vaporize, then a major human
safety threat exist (see scary pictures). A thermal fuse is placed in
series with MOVs in a desperate hope to disconnect an MOV before it
vaporizes Vaporizing MOV is a complete violation of MOV manufacturer
specs AND a human safety threat.

Think about it a minute. MOV is so grossly undersized as to
vaporize or be disconnected. It leaves the appliance to fend for
itself from surges? Yes, the fuse does not disconnect appliances.
Fuse leaves the appliance to protect itself from a surge.

So why is that appliance working while the protector failed? Surge
was too small to overwhelm protection inside the appliance. But MOV
protector was so grossly undersized as to be permanently destroyed.

By undersizing it, a plug-in protector manufacturer gets the naive
to recommend a grossly undersized protector. Effective protectors
earth surges AND remain functional - do not blow the fuse. Any
properly sized protector remains functional after a surge. So that
'failed' protector light says what about the protector? Grossly
undersized?

Another problem when that fuse does not disconnect fast enough:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articles/Surge Protectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol or
http://www.esdjournal.com/techpapr/Pharr/INVESTIGATING SURGE SUPPRESSOR FIRES.doc

IOW many plug-in protectors will fail even on smaller surges to
avoid those scary pictures. Failure also promotes sales among the
naive.

How to test an MOV? Apply a 1 ma current source to it and measure
its voltage. Remember, a vaporized MOV is a complete violation of
manufacturer specifications. MOVs must degrade; never vaporize. When
has an MOV degraded excessively? When that voltage during a 1 ma
current is more than 10% of its rated voltage. See the datasheet. A
fully degraded MOV remains functional - does not vaporize.

So again, if a surge was so large as to trip that indicator lamp,
then the protector was grossly undersized - completely ineffective.
If a power strip protector is reported defective by its indicator
light, then you have no business buying more of those grossly
undersized devices. Otherwise even the house is a risk per those
scary pictures. See the Gaston County Fire Marshall report to
appreciate the threat - the fifth citation.

 

[w_tom]

...
What is the circuit diagram for one of
these indicator LEDs, and ...

http://www.zerosurge.com/HTML/movs.html
Notice that all MOVs are remove and indicator light says protector is
good. Its not good. All MOVs are removed. Lights can only report a
catastrophic failure; not report the protector as good.

 

[[email protected]]

Thanks, everyone.

 

[bud--]

As others have noted, an MOV is 'protected' by a thermal fuse. If a
surge is so large as to cause MOV to vaporize, then a major human
safety threat exist (see scary pictures). A thermal fuse is placed in
series with MOVs in a desperate hope to disconnect an MOV before it
vaporizes Vaporizing MOV is a complete violation of MOV manufacturer
specs AND a human safety threat.

Vaporizing is a scare tactic.

MOVs have an energy (Joule) rating. They do not protect by absorbing
surge energy, but in the process of protecting they absorb enengy. When
they have absorbed an energy equal to their rating, they will conduct at
successively lower voltages, eventually conducting at 'normal' voltages
and overheating. UL has, since 1998, required disconnects for
overheating MOVs. Plug-in suppressors have their current limited by the
significant impedance of the branch circuit.

So why is that appliance working while the protector failed? Surge
was too small to overwhelm protection inside the appliance. But MOV
protector was so grossly undersized as to be permanently destroyed.

For w_, all plug-in surge suppressors are "grossly undersized". In fact
suppressors with very high ratings are readily available at rather low
cost. And apparently a surge that can destroy a MOV won't damage
protection inside an appliance? Hallucination.

By undersizing it, a plug-in protector manufacturer gets the naive
to recommend a grossly undersized protector. Effective protectors
earth surges AND remain functional - do not blow the fuse. Any
properly sized protector remains functional after a surge. So that
'failed' protector light says what about the protector? Grossly
undersized?

"Grossly undersized" red herring again.

Another problem when that fuse does not disconnect fast enough:
http://www.hanford.gov/rl/?page=556&parent=554

The hanford link describes overheating as being a problem with "some
older model" power strips and says overheating was fixed with a revision
to UL1449 that requires thermal disconnects. Overheating was fixed, for
UL listed suppressors, in 1998.

IOW many plug-in protectors will fail even on smaller surges to
avoid those scary pictures. Failure also promotes sales among the
naive.

Competently manufactured suppressors engineer the fuses/thermal
disconnects to open only when the MOVs fail. (They fail by conducting at
too low a voltage and overheating.) w_, apparently, buys only cheap
no-brand Chinese suppressors.

How to test an MOV? Apply a 1 ma current source to it and measure
its voltage.

I agree this is the way to test a MOV.

So again, if a surge was so large as to trip that indicator lamp,
then the protector was grossly undersized - completely ineffective.

The "grossly undersized" red herring again. Grossly undersized applies
equally to service panel suppressors, which will also be disconnected if
their ratings are exceeded.



w_ believes that plug-in suppressors to not work. Instead of using
technical arguments, he doesn't have any, he is using scare tactics.

For accurate information on surges and surge protection read:
http://omegaps.com/Lightning Guide_FINALpublishedversion_May051.pdf
- "How to protect your house and its contents from lightning: IEEE guide
for surge protection of equipment connected to AC power and
communication circuits" published by the IEEE in 2005 (the IEEE is the
dominant organization of electrical and electronic engineers in the US).
And also:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
- "NIST recommended practice guide: Surges Happen!: how to protect the
appliances in your home" published by the US National Institute of
Standards and Technology in 2001

The IEEE guide is aimed at those with some technical background. The
NIST guide is aimed at the unwashed masses.


The author of the NIST guide, who was the surge guru at the NIST, has
said "in fact, the major cause of TVSS [surge suppressor] failures is a
temporary overvoltage, rather than an unusually large surge."

 

[bud--]

http://www.zerosurge.com/HTML/movs.html
Notice that all MOVs are remove and indicator light says protector is
good. Its not good. All MOVs are removed. Lights can only report a
catastrophic failure; not report the protector as good.

This link is an anti-MOV propaganda piece by a manufacturer whose
suppressors do not use MOVs.

But removed MOVs are indeed a problem in areas where MOV theft rings are
active. Check with your local police to see if there is a ring active in
your area.

Lights indicate MOVs have been disconnected. Because MOVs have been
disconnected there is no "catastrophic failure".

It is very unlikely the light would be on and the suppressor would not
be functioning. (Provide an example of how.)

 

[w_tom]

This link is an anti-MOV propaganda piece by a manufacturer whose
suppressors do not use MOVs.

Bud will not admit the only reason he is here. He promotes for plug-
in protectors manufacturers, follows me everywhere posting replies,
and now makes a comment that is completely irrelevant to the
discussion.

Demonstrated was that lights did not even report missing
protection. MOV protectors are removed and light still says protector
is OK. The picture demonstrates exactly what we are discussing here.
Lights report a failure so catastrophic due to protector being
undersized.

The picture demonstrates that the lights will not report all failure
conditions. They created a failure and lights said protector was OK.
Demonstrated is that lights report only one type of failure - that
should not happen and that is too common when plug-in protectors are
grossly undersized.

Bud fears you might learn this major problem with plug-in protectors
- undersizing. He will post replies incessantly to confuse you - so
that you will also ignore these scary pictures.

These pictures come from sources who are not selling anything - a
contradiction to what Bud is doing. Indicator lamps also will not
warn of this failure. These scary pictures of current technology plug-
in protectors are too common. Threat is not because MOVs are bad.
Effective protectors are designed to provide protection; not located
in fire risky locations and not to maximize profits:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articles/Surge Protectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol
Notice the last 'scary picture' - a recent report from the Gaston
County Fire Marshall. Why would anyone place these things on a rug
or adjacent to desktop papers?

Of course Bud will reply incessantly to get the last word. He must
say anything so that your eyes will glaze over; so that you will not
remember which MOVs protectors are so ineffective. The indicator
light only reports failure when the protector was so grossly
undersized that those "scary pictures" were more probable.

 

[ehsjr]

Vaporizing is a scare tactic.

MOVs have an energy (Joule) rating. They do not protect by absorbing
surge energy, but in the process of protecting they absorb enengy.

Yes.
1) The mechanism by which they change from high resistance to
low resistance requires absorbing energy. 2) Staying in the low
resistance mode requires energy absorbtion. 3) Any energy they
absorb cannot reach the device(s) they are protecting.

Absorbing surge energy is the only way an MOV can work.
It cannot provide protection without absorbing surge energy.
That does not mean it absorbs the entire surge energy.
Where does the surge energy go? Some is absorbed and
dissipated in the source path, some in the MOV and some
in the return path.

This is a point w_tom has missed in the past when he insists
that point of use MOV's don't absorb surge energy. They most
assuredly do. If they did not absorb, they would not switch to
low resistance. When they do switch, they absorb I^2R, per ohms
law. They clamp the voltage that the device "sees" to some level
by absorbing energy. They do not absorb the entire energy that
the surge contains - just the amount of energy they "see"
that falls into their operating specs.

When
they have absorbed an energy equal to their rating, they will conduct at
successively lower voltages, eventually conducting at 'normal' voltages
and overheating. UL has, since 1998, required disconnects for
overheating MOVs. Plug-in suppressors have their current limited by the
significant impedance of the branch circuit.

So why is that appliance working while the protector failed? Surge
was too small to overwhelm protection inside the appliance. But MOV
protector was so grossly undersized as to be permanently destroyed.

For w_, all plug-in surge suppressors are "grossly undersized". In fact
suppressors with very high ratings are readily available at rather low
cost. And apparently a surge that can destroy a MOV won't damage
protection inside an appliance? Hallucination.

By undersizing it, a plug-in protector manufacturer gets the naive
to recommend a grossly undersized protector. Effective protectors
earth surges AND remain functional - do not blow the fuse. Any
properly sized protector remains functional after a surge. So that
'failed' protector light says what about the protector? Grossly
undersized?

"Grossly undersized" red herring again.

Another problem when that fuse does not disconnect fast enough:
http://www.hanford.gov/rl/?page=556&parent=554

The hanford link describes overheating as being a problem with "some
older model" power strips and says overheating was fixed with a revision
to UL1449 that requires thermal disconnects. Overheating was fixed, for
UL listed suppressors, in 1998.

IOW many plug-in protectors will fail even on smaller surges to
avoid those scary pictures. Failure also promotes sales among the
naive.

Competently manufactured suppressors engineer the fuses/thermal
disconnects to open only when the MOVs fail. (They fail by conducting at
too low a voltage and overheating.) w_, apparently, buys only cheap
no-brand Chinese suppressors.

How to test an MOV? Apply a 1 ma current source to it and measure
its voltage.

I agree this is the way to test a MOV.

So again, if a surge was so large as to trip that indicator lamp,
then the protector was grossly undersized - completely ineffective.

The "grossly undersized" red herring again. Grossly undersized applies
equally to service panel suppressors, which will also be disconnected if
their ratings are exceeded.



w_ believes that plug-in suppressors to not work. Instead of using
technical arguments, he doesn't have any, he is using scare tactics.

For accurate information on surges and surge protection read:
http://omegaps.com/Lightning Guide_FINALpublishedversion_May051.pdf
- "How to protect your house and its contents from lightning: IEEE guide
for surge protection of equipment connected to AC power and
communication circuits" published by the IEEE in 2005 (the IEEE is the
dominant organization of electrical and electronic engineers in the US).
And also:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
- "NIST recommended practice guide: Surges Happen!: how to protect the
appliances in your home" published by the US National Institute of
Standards and Technology in 2001

The IEEE guide is aimed at those with some technical background. The
NIST guide is aimed at the unwashed masses.


The author of the NIST guide, who was the surge guru at the NIST, has
said "in fact, the major cause of TVSS [surge suppressor] failures is a
temporary overvoltage, rather than an unusually large surge."

Nicely stated.

Ed

 

[bud--]

Bud will not admit the only reason he is here. He promotes for plug-
in protectors manufacturers, follows me everywhere posting replies,

To quote w_ "It is an old political trick. When facts cannot be
challenged technically, then attack the messenger." My only association
with surge protectors is I have some.

But with no valid technical arguments, w_ has to discredit those that
oppose him.

w_ uses google-groups to search for "surge" so he can spread his wisdom,
as ehsjr has seen. Unfortunately his wisdom about plug-in suppressors is
wrong - read the IEEE and/or NIST guides.

and now makes a comment that is completely irrelevant to the
discussion.

My comment was entirely about the link w_ posted and the point w_ made
in his post. My comment was entirely relevant to w_’s post.

Demonstrated was that lights did not even report missing
protection. MOV protectors are removed and light still says protector
is OK.

It is true. If you cut MOVs out of the suppressor the light will not
report the theft. Check for a MOV theft ring in your area.

In the real world, MOVs fail by starting to clamp at line voltage,
overheating and being disconnected as required by UL1449 since 1998. The
lights indicate a disconnect.

The picture demonstrates exactly what we are discussing here.
Lights report a failure so catastrophic due to protector being
undersized.

In w_’s mind, plug-in suppressors have miniscule ratings. But plug-in
suppressors are readily available with very high ratings for relatively
low cost.

The current to a plug-in suppressor is limited by the branch circuit
ratings. The energy hit a plug-in suppressor takes from a surge is
similarly greatly limited. High ratings mean a suppressor can take a
very large number of hits without failing, likely more hits than the
suppressor will experience. This allows manufacturers to have a
warrantee on the suppressor, and some manufacturers also have a
warrantee on connected equipment.

Note that suppressor has to be connected properly. In particular, all
interconnected equipment needs to be connected to the same plug-in
suppressor, or interconnecting wires need to go through the suppressor.
External connections, like phone, also need to go through the
suppressor. Connecting all wiring through the suppressor prevents
damaging voltages between power and signal wires. These multiport
suppressors are described in both guides.

The picture demonstrates that the lights will not report all failure
conditions.

w_’s propaganda picture demonstrates MOVs being deliberately cut out of
the suppressor.

In the real world, the lights indicate the MOVs are connected and still
providing protection.

Bud fears you might learn this major problem with plug-in protectors
- undersizing.

The undersized red herring. Buy suppressors with adequate ratings.

These pictures come from sources who are not selling anything - a
contradiction to what Bud is doing.

The “old political trick” #2.
And zerosurge is selling something and provides propaganda against
competing MOV technology.

Indicator lamps also will not
warn of this failure.

They warn of a failure unless you have a MOV theft ring in your area.

These scary pictures of current technology plug-
in protectors are too common. Threat is not because MOVs are bad.
Effective protectors are designed to provide protection; not located
in fire risky locations and not to maximize profits:
http://www.hanford.gov/rl/?page=556&parent=554

The lie repeated. The hanford link says overheating was fixed by a
revision to UL 1449. That was 1998. w_ has posted no link that says his
scare tactics apply to “current technology plug-in protectors.”

http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol
Notice the last 'scary picture' - a recent report from the Gaston
County Fire Marshall. Why would anyone place these things on a rug
or adjacent to desktop papers?

Recent? It is not dated. And does not say there are problems with
suppressors produced since 1998.

He must
say anything so that your eyes will glaze over; so that you will not
remember which MOVs protectors are so ineffective.

I recommend people interested in accurate information read the IEEE
and/or NIST guides. Both say plug-in suppressors are effective. Neither
guide includes w_’s scary pictures. The only 2 examples of surge
protection in the IEEE guide use plug-in suppressors.

 

[w_tom]

I recommend people interested in accurate information read the IEEE
and/or NIST guides. Both say plug-in suppressors are effective. Neither
guide includes w_'s scary pictures. The only 2 examples of surge
protection in the IEEE guide use plug-in suppressors.

So let's quote that IEEE guide that shows how plug-in protectors
might work AND what happens when it is not properly earthed. Page 42
Figure 8 in
http://omegaps.com/Lightning Guide_FINALpublishedversion_May051.pdf
shows what happens when the plug-in protector does not earth a surge.
Due to a plug-in protector too far from earth ground and too close to
the TV, therefore the TV earths that surge - 8000 volts destructively.

The effective protector earths surges. The effective protector is
not protection. Protection is earth ground. Numbers are posted in
reply to above ehsjr's 27 Aug post. In that example, earth may
dissipates (absorbs) 60 million or 100 million watts. But what
happens to that energy when the protector does not have that 'less
than 10 foot' earthing connection. Where is that surge energy
absorbed? Bud conveniently forgets that fact.

The protector without properly earthing - on Page 42 Figure 8 - it
earths that surge 8000 volts destructively through an adjacent TV.
That is effective protection? Bud hopes you ignore what his IEEE and
NIST citations state. Protectors work by earthing. No earth ground
wire? How then does it earth that surge? It does not. Plug-in
protectors don't even claim to provide protection in numerical spec
sheets. What kind of protection is that? Ineffective - but so
profitable.

 

[w_tom]

Absorbing surge energy is the only way an MOV can work.
It cannot provide protection without absorbing surge energy.
That does not mean it absorbs the entire surge energy.
Where does the surge energy go? Some is absorbed and
dissipated in the source path, some in the MOV and some
in the return path.

This is a point w_tom has missed in the past when he insists
that point of use MOV's don't absorb surge energy.

w_tom never said "MOVs do not absorb energy". Even wire absorbs
energy - which is what I post everytime in response to ehsjr's
intentional misquotes. What are functions of an MOV and of wire?
Both are shunt mode devices. Both operate by shunting (diverting,
connecting, clamping, conducting) electrical current (and energy)
elsewhere. Both absorb energy when performing their job. But neither
function is to absorb all energy - as ehsjr repeatedly claimed.

If we increase MOV joules, then MOV absorbs more energy? Of course
not. If we increase the gauge of wire, then it absorbs more energy?
No. In both cases: as MOV joules and wire gauge increase, then the
device absorbs less energy - because that is what we want it to do.
The function of wire and MOVs: absorb less energy and shunt more
energy.

If MOVs are grossly undersized, then absorbed surge energy increases
massively. That unacceptable operation causes an MOV to vaporize. A
vaporized MOV exceed manufacturer acceptable ratings. Undersized
protectors - too few joules - can also create these scary pictures:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articles/Surge Protectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol or
http://www.esdjournal.com/techpapr/Pharr/INVESTIGATING SURGE SUPPRESSOR FIRES.doc

When too much current passes through an MOV, then its voltage
increases. That unacceptable voltage increase is when an MOV is
grossly undersized - has too few joules. We increase MOV joules so
that an MOV does not absorb more energy; just as we increase wire
diameter.

From manufacturer data sheet: An MOV for 120 volt operation rated
at 25 joules (241KD09 is an 11 mm MOV disk) see voltage climb quickly
past 800 volts during a 2500 amp surge because it is undersized - too
few joules. That peak 2 million watt surge dissipated in that MOV
means its life expectancy is 1 surge (does not vaporize). If we
increase to a 72 joules MOV (241KD18 is a 22 mm disk)). Then a 2500
amp surge creates an MOV voltage of 550; only 1.4 million watts
dissipated in that MOV. Larger MOV means increased life expectancy
and less energy absorbed by the MOV. Better protectors (more joules)
absorb less energy.

What happens if we use five 72 joule MOVs? 110 amps through each
MOV means each MOV voltage is 320 volts - 35,000 watts per MOV or
0.175 million watts total. Increasing from 25 joules to 360 joules
means MOV absorbs 11.5 times less energy. Meanwhile, the 360 joule
protector is now rated for about 3000 surges. Increases joules also
means life expectancy increases exponentially.

Why do some foolishly claim a protector is only for one surge? Why
did a plug-in protector manufacturer charge so much for so few joules?

When joules increase, MOV absorbs less energy AND MOV life
expectancy increases massively. The purpose of an MOV is not to
absorb 'more' surge as ehsjr claimed. More joules means the MOV
absorbs 'less' energy AND lasts longer - just like increasing wire
size.

ehsjr and this poster have argued this for maybe seven years. ehsjr
insisted MOVs provide protection by absorbing the entire surge. MOVs
do not. Is ehsjr finally backing off that claim?

MOVs are shunt mode devices. Like wires, MOVs are not perfect
conductors; absorb a minority of a surge. Whereas that large MOV
might dissipate 1.4 million peak watts, a same surge may also
dissipate 60 or 100 million peak watts into earth. What makes an MOV
effective? Earth ground is the protection. Earth ground is where
maybe 40 or 70 times more energy is dissipated.

A protector without earth ground means no effective protection.
Earth is where the brunt of a surge energy is absorbed; not inside an
MOV as ehsjr once repeatedly claimed.

What makes an MOV effective? MOV resistance drops so that a surge
is shunted to and dissipated by earth ground. Demonstrated above is
how the 72 joule MOV absorbs 30% less energy compared to a 25 joule
MOV. As MOV joules increase, then absorbed MOV energy decreases.

Where is most all surge energy dissipated? Not inside an MOV. Above
numbers make that obvious. Effective protection means most surge
energy is dissipated in earth. But since MOVs are not perfect, then
MOVs (like wires) absorb some of that energy. I was posting this to
ehsjr seven years ago. ehsjr still misrepresents what w_tom has
posted.

 

[ehsjr]

w_tom never said "MOVs do not absorb energy".

You most certainly did:

Quoting what you wrote on 15 Apr 2006 00:04:07 -0700
under the subject "Re: surge protector question" in the
alt.engineering.electrical newsgroup:

"Shunt mode protectors do not to suppress, absorb,
dissipate, or arrest energy as ehsjr repeatedly
claims over so many years. "

The full post, including header data, is shown at the
bottom, between the lines of asterisks.

You've gone too far with your accusations this time.

Even wire absorbs
energy - which is what I post everytime in response to ehsjr's
intentional misquotes.

You are the master of intentional misquotes. I have never
intentionally misquoted you, and I doubt that I have ever
done it unintentionally. You have done it often, intentionally.

What are functions of an MOV and of wire?
Both are shunt mode devices. Both operate by shunting (diverting,
connecting, clamping, conducting) electrical current (and energy)
elsewhere. Both absorb energy when performing their job. But neither
function is to absorb all energy - as ehsjr repeatedly claimed.

I have *NEVER* stated that the MOV function is
to absorb *all* energy. That is a blatant lie.

What I *have* said, consistently, is that an MOV
will absorb whatever surge energy it "sees" at its
leads that is within the MOV's specs, until it dies
or until the voltage drops below the spec.

ehsjr and this poster have argued this for maybe seven years. ehsjr
insisted MOVs provide protection by absorbing the entire surge.

Blatant lie. I have *NEVER* said "MOVs provide protection
by absorbing the entire surge".

Where is most all surge energy dissipated? Not inside an MOV. Above
numbers make that obvious. Effective protection means most surge
energy is dissipated in earth. But since MOVs are not perfect, then
MOVs (like wires) absorb some of that energy. I was posting this to
ehsjr seven years ago. ehsjr still misrepresents what w_tom has
posted.

The post I quoted from you at the begining of my reply proves
you are the one who misrepresents what you have said.
You've hoisted yourself on your own petard.

Ed




*****************************************************************************
Subject:
Re: surge protector question
From:
"w_tom" <[email protected]>
Date:
15 Apr 2006 00:04:07 -0700
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Because "energy will be absorbed & dissipated when current flows
through a resistance" then the purpose of wire is to absorb and
dissipate electrical energy. Surge protectors, like wire, will
dissipate some energy when performing their function: to conduct,
shunt, divert, transport that electricity. Shunt mode protectors do
not to suppress, absorb, dissipate, or arrest energy as ehsjr
repeatedly claims over so many years. Although some energy is
dissipated (neither wire nor protectors are perfect conductors), well,
a one hundred joule protector will absorb how many joules in a
lightning strike? (One joule is one volt and one amp for one second:
how many in lightning?) How many joules will that 100 joule protector
suppress, absord, or arrest?

A wire diverts (conducts) energy to my vacuum cleaner. How many
joules has its power cord suppressed, absorbed, dissipated, or
arrested? About 3700 joules. Well that proves it. The purpose of a
power cord is to absorb electricity. Meanwhile the power cord carries
another 3,456,000 joules into the vacuum cleaner. Irrelevant. That
wire dissipated / absorbed energy. Absorbing enery must be its
purpose.

When ehsjr posts this same refrain, a credible source is cited in
reply. This time the National Institute of Science and Technology is
quoted from in their publication 960-6 entitled "Surges Happen! How to
Protect the Appliances in your Home.":

*****************************************************************************

 

[ehsjr]

So let's quote that IEEE guide that shows how plug-in protectors
might work AND what happens when it is not properly earthed. Page 42
Figure 8 in
http://omegaps.com/Lightning Guide_FINALpublishedversion_May051.pdf
shows what happens when the plug-in protector does not earth a surge.
Due to a plug-in protector too far from earth ground and too close to
the TV, therefore the TV earths that surge - 8000 volts destructively.

Yes - let's cite it *accurately*, and note that when you read
all of the information,the IEEE guide clearly indicates that
point of use protectors can be of value in protecting your gear.
First, figure 8 is on page 33, not on page 42 as you indicated.
The last line in the text description for figure 8 says: "A second
multi-port protector as shown in figure 7 is required to protect TV2."
The last line in the text description under figure 7 says: "The
multiport protector shown at the TV set can greatly decrease the
voltage between the AC ground and the coax cable, preventing damage
to the set."

That is from the IEEE guide you are recommending, and it clearly
shows that point of use protectors can be of value in protecting
your equipment.

The effective protector earths surges. The effective protector is
not protection. Protection is earth ground. Numbers are posted in
reply to above ehsjr's 27 Aug post. In that example, earth may
dissipates (absorbs) 60 million or 100 million watts. But what
happens to that energy when the protector does not have that 'less
than 10 foot' earthing connection. Where is that surge energy
absorbed? Bud conveniently forgets that fact.

The protector without properly earthing - on Page 42 Figure 8 - it
earths that surge 8000 volts destructively through an adjacent TV.
That is effective protection?

Why don't you read the whole thing? It *plainly* tells you that
a second multi-port protector is *REQUIRED*.

Bud hopes you ignore what his IEEE and
NIST citations state.

Where do you get off stating what Bud hopes?

Protectors work by earthing. No earth ground
wire? How then does it earth that surge? It does not. Plug-in
protectors don't even claim to provide protection in numerical spec
sheets. What kind of protection is that? Ineffective - but so
profitable.

Again, you bash plug-in protectors, when the very guide
you cite says: "The multiport protector shown at the TV set
can greatly decrease the voltage between the AC ground and
the coax cable, preventing damage to the set."
See figure 7, page 32.

Quoting Section 5.1 page 38:

"Most plug-in AC protectors use MOVs rated for 130 V AC RMS, and
have a surge limiting voltage of ~330 V peak for the 500A test
pulse. So, plug-in protectors tend to provide lower limiting
voltages (better protection for equipment) for moderate incoming
surges. The gap widens when more realistic surges, and the effects
of wiring, are considered."

Repeating for emphasis: *better protection for equipment*.

Continuing the quote:
"Section 2.3.2 pointed out how rapidly the lead length raises the
effective limiting voltage of hard-wired protectors for large current
impulses. For a typical installation with 20 inches (50 cm) leads,
the effective limiting voltage at the panel would be ~1160 V for a
10 kA impulse (see Table 1). In a well-constructed plug-in protector,
the load is connected directly across the MOVs (Figure 6B), and there
should be negligible voltage drop in the MOV leads. So for the same
10,000 A surge current, the load can actually see a ~400–500 V
effective limiting voltage (with 130 V MOVs), much smaller than
allowed by the hard-wired protector, and much more protective for the
equipment."

Repeating for emphasis: *much more protective for the equipment*

Continuing the quote:
"Well-designed and well-built plug-in protectors will actually
withstand the 10,000 A (8x20 μs) surge current, and that is
rating required by NFPA 780-2004 for plug-in protectors.
However, the UL 1449 Standard only requires plug-in protectors
to withstand, without damage, ~20 500 A surges. Inexpensive
protectors using the 6C type of circuit are designed to respond
to overload by opening the protective fusing shown in Figure 6C,
sometimes at surge currents barely over the 500 A limit. Because
the UL 500 A surge withstand requirements are relatively weak, it
is important to have both a hard-wired protector at the service
entrance and a plug-in protector at the critical loads."

Repeating for emphasis: *it is important to have a hard-wired*
*protector for the service panel and a plug-in protector at*
*the critical loads*

Tom, the guide you cited *clearly* recommends plug-in protectors.
It states thay provide better protection. If you are honest with
yourself, you will stop bashing them, and perhaps recommend them,
as the IEEE guide does, in conjunction with the ideas you have
put forward about a single point grounding system with a short,
straight connection to an effective electrode grounding system.

Ed

 

[bud--]

The effective protector earths surges. The effective protector is
not protection. Protection is earth ground.

Trying to not duplicate Ed’s post -

w_ has a religious belief (immune from challenge) that surge protection
must use earthing. Thus in his view plug-in suppressors (which are not
well earthed) can not possibly work. The IEEE guide explains plug-in
suppressors work by CLAMPING the voltage on all wires (signal and power)
to the common ground at the suppressor. Plug-in suppressors do not work
primarily by earthing. The guide explains earthing occurs elsewhere.
(Read the guide starting pdf page 40).

The protector without properly earthing - on Page 42 Figure 8 - it
earths that surge 8000 volts destructively through an adjacent TV.

The illustration in the IEEE guide has a surge coming in on a CATV drop.
There are 2 TVs, one is on a plug-in suppressor. The plug-in suppressor
protects TV1, connected to it.

Without the plug-in suppressor the surge voltage at TV2 is 10,000V. With
the suppressor at TV1 the voltage at TV2 is 8,000V. It is simply a *lie*
that the plug-in suppressor at TV1 in any way contributes to the damage
at TV2.

The point of the illustration for the IEEE, Ed, and anyone else who can
think, is "to protect TV2, a second multiport protector located at TV2
is required."

Because plug-in suppressors violate w_'s religious belief in earthing
he has to twist what the IEEE guide says about them.

w_ says suppressors must only be at the service panel. In this example a
service panel protector would provide absolutely *NO* protection. The
problem is the wire connecting the CATV entry block to the power service
is too long, as is the case in many houses. The IEEE guide says in that
case "the only effective way of protecting the equipment is to use a
multiport protector."


Note that a critical feature of a “single point ground” is that entrance
protectors for CATV, phone, ... connected with a *short* wire to the
earth electrode conductor at the power panel. This was violated in the
IEEE example above. With a large surge, the house ground will always
rise above `absolute' ground. The goal is for the power and CATV and
phone 'grounds' to rise together.

According to NIST guide, US insurance information indicates equipment
most frequently damaged by lightning is
computers with a modem connection
TVs, VCRs and similar equipment (presumably with cable TV
connections).
All can be damaged by high voltages between power and signal wires.

Bud hopes you ignore what his IEEE and
NIST citations state.

I hope people will read the guides - excellent sources.

w_ has never explained:
- Why do the only 2 examples of protection in the IEEE guide use plug-in
suppressors?
- Why does the NIST guide says plug-in suppressors are "the easiest
solution"?

Protectors work by earthing.

The required statement of religious belief in earthing.

The question is not earthing - everyone is for it. The only question is
whether plug-in suppressors work. Both the IEEE and NIST guides say
plug-in suppressors are effective. Read the sources.

There are 98,615,938 other web sites, including 13,843,032 by lunatics,
and w_ can't find another lunatic that says plug-in suppressors are NOT
effective. All you have is w_'s opinions based on his religious belief
in earthing.

 

[w_tom]

Continuing the quote:
"Well-designed and well-built plug-in protectors will actually
withstand the 10,000 A (8x20 s) surge current, and that is
rating required by NFPA 780-2004 for plug-in protectors.
However, the UL 1449 Standard only requires plug-in protectors
to withstand, without damage, ~20 500 A surges. Inexpensive
protectors using the 6C type of circuit are designed to respond
to overload by opening the protective fusing shown in Figure 6C,
sometimes at surge currents barely over the 500 A limit. Because
the UL 500 A surge withstand requirements are relatively weak, it
is important to have both a hard-wired protector at the service
entrance and a plug-in protector at the critical loads."

That right. It's important to have hard-wired protector at the
service entrance that has that short connection to earth ground. And
$2000 or $4000 worth of plug-in protectors? Remember we must install
them on dishwasher electronics, dimmer switches, and most critical
appliances such as bathroom GFCIs and smoke detectors. Or maybe those
critical devices are best protected by a 'whole house' protector that
is properly earthed.

As the guide says repeatedly, a protector works by earthing. If the
earthing is not sufficient, then how does a plug-in protector put more
current into an earth ground what would not accept that current
initially? It does not.

How do we make better protection? We enhance what provides the
protection. We upgrade the earthing.

Without that 'whole house' protector, then those supplemental
protection - plug-in protectors - are not sufficient. How
insufficient? Again the scary pictures demonstrate the problem of
grossly undersized plug-in protectors you are recommending:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articles/Surge Protectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol or
http://www.esdjournal.com/techpapr/Pharr/INVESTIGATING SURGE SUPPRESSOR FIRES.doc

And that is what the guide is also noting. Plug-in protectors alone
are not effective. The guide says plug-in protectors can work IF
massive cautions are taken. Meanwhile what does your telco do to
operate during every thunderstorm? Do they disconnect their switching
computers to protect them from lightning? Of course not. Those
computers are connected to overhead wires all over town and must not
suffer damage.

They use properly earthed 'whole house' protectors on every incoming
wire - and no plug-in protectors. To have effective protection
without spending massively, the telco uses a 'whole house' protector
AND better earthing.

How did the Orange County FL emergency response center stop damage?
They also did not waste money on plug-in protectors that are also a
fire hazard. Instead they upgraded the earthing. Why upgrade the
earthing? Even the IEEE guide says it. Protectors don't stop or
absorb surges as ehsjr had claimed even on 29 May 2005. Earthing
provides the protection. Orange County stopped surge damage by not
using plug-in protectors AND by enhancing the earthing. They spend
money where money would be useful which meant upgrading earthing:
http://www.psihq.com/AllCopper.htm

Why do you recommend protectors that the guide even warns as poor?
Meanwhile the IEEE defines the only thing that provides protection in
their Red Book (Standard 141) and in many other standards. No they
don't recommend plug-in protectors. IEEE recommends the only thing
that provides protection - earth ground:
:> In actual practice, lightning protection is achieve by the

process of interception of lightning produced surges,
diverting them to ground, and by altering their
associated wave shapes.

Yes one can supplement protection with grossly undersized and
massively more expensive plug-in protectors. And then the guide also
shows why plug-in protectors will fail to provide protection.

Meanwhile Page 42 Figure 8 of the other citation also shows what
telcos know. A protector too close to appliances and too far from
earth ground many even earth the surge 8000 volts destructively
through an adjacent TV. Therefore telcos that operate without damage
during every thunderstorm put the protector within feet of earth
ground AND up to 50 meters distant from electronics. Why 50 meters?
That separation also makes the earthed protector more effective. The
protector adjacent to an appliance may even earth that surge
destructively through that appliance. How curious. We engineers saw
this happen even 20 years ago.

We engineers also knew that protectors do not work by absorbing all
the surge energy - as ehsjr repeatedly claimed seven years ago.