AC Power Surge Protection?

[KenO]

A friend recently had her audio system damaged from an AC Power Surge.

Would like to prevent this so Googled using AC Power Surge Protection and found "The Best Surge Protector by Brent Butterworth.
http://thewirecutter.com/reviews/best-surge-protector/

Read link "Surge Protectors ??? (Brickwall, Zero Surge, Furman, SurgeX," http://www.avsforum.com/forum/40-oled-technology-flat-panels-general/1146963-surge-protectors-brickwall-zero-surge-furman-surgex-etc.html

Then did a Forum search and found some very long discussions such as:
Surge Protectors https://groups.google.com/forum/#!searchin/sci.electronics.repair/AC$20Power$20Surge$20Protection%7Csort:relevance/sci.electronics.repair/mkLpyahIKNk/3GvjxW9LrrsJ

Surge protector fuse blown https://groups.google.com/forum/#!searchin/sci.electronics.repair/AC$20Power$20Surge$20Protection%7Csort:relevance/sci.electronics.repair/iUffPhXZsNA/Ay8058Ba46QJ

I do not have a technical background so would be interested in others comments concerning all this.

Would like to use your advice to build a cost effective audio protection system.

Thanks

Ken

 

[Phil Allison]

KenO wrote:

A friend recently had her audio system damaged from an AC Power Surge.

** AC power voltage surges damaging audio gear are so rare that I cannot accept it as true without convincing evidence.

The DC power supply inside each piece of audio gear usually contains a transformer, rectifier and filter electros - a combination that eliminates AC voltage spikes/surges better than anything you can possibly buy or build.

OTOH, the term "power surge" is regularly used to explain away sudden failures in almost any electronic device - when the real cause is simply a bad component.


..... Phil

 

[Trevor Wilson]

On 27/05/2015 9:12 AM, KenO wrote:

A friend recently had her audio system damaged from an AC Power
Surge.

**How do you know it was a "power surge"? Where did this alleged "power
surge" originate?

Would like to prevent this so Googled using AC Power Surge Protection
and found "The Best Surge Protector by Brent Butterworth.
http://thewirecutter.com/reviews/best-surge-protector/

Read link "Surge Protectors ??? (Brickwall, Zero Surge, Furman,
SurgeX,"
http://www.avsforum.com/forum/40-oled-technology-flat-panels-general/1146963-surge-protectors-brickwall-zero-surge-furman-surgex-etc.html

Then did a Forum search and found some very long discussions such
as: Surge Protectors
https://groups.google.com/forum/#!searchin/sci.electronics.repair/AC$20Power$20Surge$20Protection%7Csort:relevance/sci.electronics.repair/mkLpyahIKNk/3GvjxW9LrrsJ

Surge protector fuse blown
https://groups.google.com/forum/#!searchin/sci.electronics.repair/AC$20Power$20Surge$20Protection%7Csort:relevance/sci.electronics.repair/iUffPhXZsNA/Ay8058Ba46QJ

I do not have a technical background so would be interested in
others comments concerning all this.

Would like to use your advice to build a cost effective audio
protection system.

**The best way to protect an audio system from "power surges" is to
disconnect the TV antenna during lightning storms, since that is, far
and away, the most common source of "power surges". Mains bourne "power
surges" are incredibly rare events and almost nothing available off the
shelf can deal with the energies involved.


--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com

 

[N_Cook]

On 27/05/2015 02:35, Trevor Wilson wrote:

On 27/05/2015 9:12 AM, KenO wrote:
A friend recently had her audio system damaged from an AC Power
Surge.

**How do you know it was a "power surge"? Where did this alleged "power
surge" originate?


Would like to prevent this so Googled using AC Power Surge Protection
and found "The Best Surge Protector by Brent Butterworth.
http://thewirecutter.com/reviews/best-surge-protector/

Read link "Surge Protectors ??? (Brickwall, Zero Surge, Furman,
SurgeX,"
http://www.avsforum.com/forum/40-oled-technology-flat-panels-general/1146963-surge-protectors-brickwall-zero-surge-furman-surgex-etc.html


Then did a Forum search and found some very long discussions such
as: Surge Protectors
https://groups.google.com/forum/#!searchin/sci.electronics.repair/AC$20Power$20Surge$20Protection%7Csort:relevance/sci.electronics.repair/mkLpyahIKNk/3GvjxW9LrrsJ


Surge protector fuse blown
https://groups.google.com/forum/#!searchin/sci.electronics.repair/AC$20Power$20Surge$20Protection%7Csort:relevance/sci.electronics.repair/iUffPhXZsNA/Ay8058Ba46QJ


I do not have a technical background so would be interested in
others comments concerning all this.

Would like to use your advice to build a cost effective audio
protection system.

**The best way to protect an audio system from "power surges" is to
disconnect the TV antenna during lightning storms, since that is, far
and away, the most common source of "power surges". Mains bourne "power
surges" are incredibly rare events and almost nothing available off the
shelf can deal with the energies involved.

Well you survived long enough to provide this homicidal info.
You disconnect TV aerials BEFORE lightening storms.

 

[Tim R]

On Wednesday, May 27, 2015 at 3:28:50 AM UTC-4, N_Cook wrote:

**The best way to protect an audio system from "power surges" is to
disconnect the TV antenna during lightning storms, since that is, far
and away, the most common source of "power surges". Mains bourne "power
surges" are incredibly rare events and almost nothing available off the
shelf can deal with the energies involved.



Well you survived long enough to provide this homicidal info.
You disconnect TV aerials BEFORE lightening storms.

Yeah, I always wait until between flashes to climb the mast and disconnect the antenna.

 

[Baron]

Phil Allison prodded the keyboard with:

KenO wrote:

A friend recently had her audio system damaged from an AC Power
Surge.


** AC power voltage surges damaging audio gear are so rare that I
cannot accept it as true without convincing evidence.

The DC power supply inside each piece of audio gear usually contains
a transformer, rectifier and filter electros - a combination that
eliminates AC voltage spikes/surges better than anything you can
possibly buy or build.

OTOH, the term "power surge" is regularly used to explain away
sudden failures in almost any electronic device - when the real
cause is simply a bad component.


.... Phil

+1
--
Best Regards:
Baron.

 

[Gareth Magennis]

"Baron" wrote in message news:mk4gc9$7fm$1@dont-email.me...

Phil Allison prodded the keyboard with:

KenO wrote:

A friend recently had her audio system damaged from an AC Power
Surge.


** AC power voltage surges damaging audio gear are so rare that I
cannot accept it as true without convincing evidence.

The DC power supply inside each piece of audio gear usually contains
a transformer, rectifier and filter electros - a combination that
eliminates AC voltage spikes/surges better than anything you can
possibly buy or build.

OTOH, the term "power surge" is regularly used to explain away
sudden failures in almost any electronic device - when the real
cause is simply a bad component.


.... Phil

+1
--
Best Regards:
Baron.




Many years ago I was working for a PA Hire company. One day we had a real
"power surge".
All the lights started getting really bright, then normal again, then back
to really bright etc. It was quite a weird experience.
I seem to recall we hit the emergency Power Off button in the warehouse
after measuring the mains outlets being well above 300v.

Most of the office equipment got fried - photocopier, printer etc. but no
humans or any of the audio gear were hurt.

We called in the electricity supply company, who (they said) discovered a
bad Mains Intake Neutral connection.
They paid compensation for all the fried gear, and we all saw the funny
side.




Gareth.

 

[Ron D.]

I'll point you here: http://www.gryphon-inc.com/White_Papers.html

I've had extreme success with Powervar/ONEAC products. Like 25 years on a very critical computer system. The only failures were mechanical like fans and floppy drives. The hard drive was on 15 years before the system was upgraded. It did cost about $1K USD in the 80's for about 1000 W. Later, two other systems got the same technology.

Usually, the warranty and the sales receipt helps a lot. Less critical systems got the tripp-lite isobar which oneac doesn;t like either. I did see an ISOBAR fry and Trip-lite replaced the connected equipment.

I had an APC surge suppressor (given to me) and it's is supposed to be replaced because it causes fires. I think it's been close to 3 months now and no replacement APC. Furthermore, that APC did not protect itself. Oh maybe it did? It prevent itself from frying by blowing a thermal fuse and passing the surge to the equipment and lighting a LED.

 

[Trevor Wilson]

On 27/05/2015 5:28 PM, N_Cook wrote:

On 27/05/2015 02:35, Trevor Wilson wrote:
On 27/05/2015 9:12 AM, KenO wrote:
A friend recently had her audio system damaged from an AC Power
Surge.

**How do you know it was a "power surge"? Where did this alleged "power
surge" originate?


Would like to prevent this so Googled using AC Power Surge Protection
and found "The Best Surge Protector by Brent Butterworth.
http://thewirecutter.com/reviews/best-surge-protector/

Read link "Surge Protectors ??? (Brickwall, Zero Surge, Furman,
SurgeX,"
http://www.avsforum.com/forum/40-oled-technology-flat-panels-general/1146963-surge-protectors-brickwall-zero-surge-furman-surgex-etc.html



Then did a Forum search and found some very long discussions such
as: Surge Protectors
https://groups.google.com/forum/#!searchin/sci.electronics.repair/AC$20Power$20Surge$20Protection%7Csort:relevance/sci.electronics.repair/mkLpyahIKNk/3GvjxW9LrrsJ



Surge protector fuse blown
https://groups.google.com/forum/#!searchin/sci.electronics.repair/AC$20Power$20Surge$20Protection%7Csort:relevance/sci.electronics.repair/iUffPhXZsNA/Ay8058Ba46QJ



I do not have a technical background so would be interested in
others comments concerning all this.

Would like to use your advice to build a cost effective audio
protection system.

**The best way to protect an audio system from "power surges" is to
disconnect the TV antenna during lightning storms, since that is, far
and away, the most common source of "power surges". Mains bourne "power
surges" are incredibly rare events and almost nothing available off the
shelf can deal with the energies involved.



Well you survived long enough to provide this homicidal info.
You disconnect TV aerials BEFORE lightening storms.

**OUCH! You are, of course, correct.

--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com

 

[Ron D.]

On Wednesday, May 27, 2015 at 5:16:28 PM UTC-4, Ron D. wrote:

I'll point you here: http://www.gryphon-inc.com/White_Papers.html

I've had extreme success with Powervar/ONEAC products. Like 25 years on a very critical computer system. The only failures were mechanical like fans and floppy drives. The hard drive was on 15 years before the system was upgraded. It did cost about $1K USD in the 80's for about 1000 W. Later, two other systems got the same technology.

Usually, the warranty and the sales receipt helps a lot. Less critical systems got the tripp-lite isobar which oneac doesn;t like either. I did see an ISOBAR fry and Trip-lite replaced the connected equipment.

I had an APC surge suppressor (given to me) and it's is supposed to be replaced because it causes fires. I think it's been close to 3 months now and no replacement APC. Furthermore, that APC did not protect itself. Oh maybe it did? It prevent itself from frying by blowing a thermal fuse and passing the surge to the equipment and lighting a LED.

A whole house suppressor would not be a bad idea either.

 

[Trevor Wilson]

On 28/05/2015 12:21 PM, Ron D. wrote:

On Wednesday, May 27, 2015 at 5:16:28 PM UTC-4, Ron D. wrote:
I'll point you here: http://www.gryphon-inc.com/White_Papers.html

I've had extreme success with Powervar/ONEAC products. Like 25
years on a very critical computer system. The only failures were
mechanical like fans and floppy drives. The hard drive was on 15
years before the system was upgraded. It did cost about $1K USD in
the 80's for about 1000 W. Later, two other systems got the same
technology.

Usually, the warranty and the sales receipt helps a lot. Less
critical systems got the tripp-lite isobar which oneac doesn;t like
either. I did see an ISOBAR fry and Trip-lite replaced the
connected equipment.

I had an APC surge suppressor (given to me) and it's is supposed to
be replaced because it causes fires. I think it's been close to 3
months now and no replacement APC. Furthermore, that APC did not
protect itself. Oh maybe it did? It prevent itself from frying by
blowing a thermal fuse and passing the surge to the equipment and
lighting a LED.

A whole house suppressor would not be a bad idea either.

**For what purpose? An event that is so incredibly rare that the average
person won't see one in several life-times.

The whole 'surge suppressor' industry is a con. It is the only
significant profit area left for retailers of domestic electronic
equipment. Profit margins run to several hundred percent. That said: A
whole house suppressor is a reasonably economical solution to an almost
non-existent problem. It must be fitted by a qualified electrical
contractor.

FWIW: The only time I have ever heard of a significant surge on a power
line, was at my previous home, before I moved in. A 5kV railway bearer
fell across the 240VAC mains supply. This was in the early 1970s. It
wiped out the electronic and electrical equipment for several blocks. I
doubt that anything that can be purchased retail can protect against
such a rare event.

--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com

 

[gregz]

Trevor Wilson <trevor@SPAMBLOCKrageaudio.com.au> wrote:

On 28/05/2015 12:21 PM, Ron D. wrote:
On Wednesday, May 27, 2015 at 5:16:28 PM UTC-4, Ron D. wrote:
I'll point you here: http://www.gryphon-inc.com/White_Papers.html

I've had extreme success with Powervar/ONEAC products. Like 25
years on a very critical computer system. The only failures were
mechanical like fans and floppy drives. The hard drive was on 15
years before the system was upgraded. It did cost about $1K USD in
the 80's for about 1000 W. Later, two other systems got the same
technology.

Usually, the warranty and the sales receipt helps a lot. Less
critical systems got the tripp-lite isobar which oneac doesn;t like
either. I did see an ISOBAR fry and Trip-lite replaced the
connected equipment.

I had an APC surge suppressor (given to me) and it's is supposed to
be replaced because it causes fires. I think it's been close to 3
months now and no replacement APC. Furthermore, that APC did not
protect itself. Oh maybe it did? It prevent itself from frying by
blowing a thermal fuse and passing the surge to the equipment and
lighting a LED.

A whole house suppressor would not be a bad idea either.


**For what purpose? An event that is so incredibly rare that the average
person won't see one in several life-times.

Some time after installing a whole house suppressor, we had an instance
where power was going off and on during a storm. A loud crack downstairs,
found suppressor blown. I replaced that one but have not found any other
local supressor faulted that I know of. The model has a lower trip point
voltage to other models I've seen. When I moved in this house the power
company said a surge device was installed and if I wanted to pay monthly
charge. I sad no, but never knew of anybody removing it from the meter,
which would require power interruption.
These things will not help a direct lightning hit.

Greg

The whole 'surge suppressor' industry is a con. It is the only
significant profit area left for retailers of domestic electronic
equipment. Profit margins run to several hundred percent. That said: A
whole house suppressor is a reasonably economical solution to an almost
non-existent problem. It must be fitted by a qualified electrical contractor.

FWIW: The only time I have ever heard of a significant surge on a power
line, was at my previous home, before I moved in. A 5kV railway bearer
fell across the 240VAC mains supply. This was in the early 1970s. It
wiped out the electronic and electrical equipment for several blocks. I
doubt that anything that can be purchased retail can protect against such a rare event.

 

[John-Del]

On Thursday, May 28, 2015 at 1:24:00 AM UTC-4, Trevor Wilson wrote:

A whole house suppressor would not be a bad idea either.


**For what purpose? An event that is so incredibly rare that the average
person won't see one in several life-times.

Every summer we see TVs come in with blown bridge rectifiers and vaporized pc traces. As long as it's confined to the primary side of the power supply it's no big deal. Any fine damaged traces on the secondary means we go no further. My own TV (1991 RCA CTC169) got whacked when I was watching it. Blew everything from the SMPS primary back including circuit traces, and was left with two other issues (odd system control vol/mute function and loss of AV switching).

 

[Tim R]

On Thursday, May 28, 2015 at 7:31:46 AM UTC-4, John-Del wrote:

On Thursday, May 28, 2015 at 1:24:00 AM UTC-4, Trevor Wilson wrote:


A whole house suppressor would not be a bad idea either.


**For what purpose? An event that is so incredibly rare that the average
person won't see one in several life-times.


Every summer we see TVs come in with blown bridge rectifiers and vaporized pc traces. As long as it's confined to the primary side of the power supply it's no big deal. Any fine damaged traces on the secondary means we go no further. My own TV (1991 RCA CTC169) got whacked when I was watching it. Blew everything from the SMPS primary back including circuit traces, and was left with two other issues (odd system control vol/mute function and loss of AV switching).

Is there any difference in the robustness of the old tube TV versus the flat screen, when it comes to lightning etc.?

 

[John-Del]

On Thursday, May 28, 2015 at 8:40:10 AM UTC-4, Tim R wrote:

Is there any difference in the robustness of the old tube TV versus the flat screen, when it comes to lightning etc.?

Only with regard to HDMI ports, which are *very* susceptible to lightning damage. Since the newest generation now does HDMI switching in the main IC which is BGA, damage through the HDMI ports means a new main board. I recommend my customers to use the component inputs when using cable, sat, or IP TV. I haven't seen any damage yet via bluray player.

 

[Mark Justice]

On Thu, 28 May 2015 15:22:28 +1000, Trevor Wilson wrote:

On 28/05/2015 12:21 PM, Ron D. wrote:
On Wednesday, May 27, 2015 at 5:16:28 PM UTC-4, Ron D. wrote:
I'll point you here: http://www.gryphon-inc.com/White_Papers.html

I've had extreme success with Powervar/ONEAC products. Like 25 years
on a very critical computer system. The only failures were mechanical
like fans and floppy drives. The hard drive was on 15 years before
the system was upgraded. It did cost about $1K USD in the 80's for
about 1000 W. Later, two other systems got the same technology.

Usually, the warranty and the sales receipt helps a lot. Less
critical systems got the tripp-lite isobar which oneac doesn;t like
either. I did see an ISOBAR fry and Trip-lite replaced the connected
equipment.

I had an APC surge suppressor (given to me) and it's is supposed to be
replaced because it causes fires. I think it's been close to 3 months
now and no replacement APC. Furthermore, that APC did not protect
itself. Oh maybe it did? It prevent itself from frying by blowing a
thermal fuse and passing the surge to the equipment and lighting a
LED.

A whole house suppressor would not be a bad idea either.


**For what purpose? An event that is so incredibly rare that the average
person won't see one in several life-times.

The whole 'surge suppressor' industry is a con. It is the only
significant profit area left for retailers of domestic electronic
equipment. Profit margins run to several hundred percent. That said: A
whole house suppressor is a reasonably economical solution to an almost
non-existent problem. It must be fitted by a qualified electrical
contractor.

FWIW: The only time I have ever heard of a significant surge on a power
line, was at my previous home, before I moved in. A 5kV railway bearer
fell across the 240VAC mains supply. This was in the early 1970s. It
wiped out the electronic and electrical equipment for several blocks. I
doubt that anything that can be purchased retail can protect against
such a rare event.

Not in Florida.
I was checking a Sunbeam frying pan to see if it worked plugging it in in
the garage when kbang.
Tossed across the garage I went to see what was damaged, besides me.

Several outlets in the house had carbon scarring around them, the
splitter to the color T.V. was mostly vaporized with just a small piece
of circuit board with the ghostly outlines of parts no longer of the
Earth.

The color T.V. worked only as black and white for some weeks when the
color decided to return.
Outside a bruise or three and a short case of the stunned shakes I was
unhurt.

Not unusual around these parts to lose equipment due to surges coming in
through the line, YMMV

 

[Cydrome Leader]

Phil Allison <pallison49@gmail.com> wrote:

KenO wrote:

A friend recently had her audio system damaged from an AC Power Surge.


** AC power voltage surges damaging audio gear are so rare that I cannot accept it as true without convincing evidence.

The DC power supply inside each piece of audio gear usually contains a transformer, rectifier and filter electros - a combination that eliminates AC voltage spikes/surges better than anything you can possibly buy or build.

That may be true if the stereo or whatever is not attached to other
devices. Once you connect things together, damage from power surges starts
to happen.

It's quite common with computer network gear. Interconnected ports fail,
while the main switch chassis or network attached printer or computer
continue to work.

Service entrance surge surpressors protect against this sort of issue.

> OTOH, the term "power surge" is regularly used to explain away sudden failures in almost any electronic device - when the real cause is simply a bad component.

power surges and the damage they cause are very real problems.

FWIW somebod mentioned powervar and Oneac devices, it wasn't clear what
these devices were, but if they were isolation/filter units, they work
great.

Stuff from tripplite is pure junk, had many of their devices catch on
fire, without surges. It was always caused by poor crimps and junky power
switches or bad assembly.

APC power strips are better, never had one self destruct yet.

 

[bud--]

On 5/26/2015 5:12 PM, KenO wrote:

Excellent information on surges and surge protection is at:
http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.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 a
major organization of electrical and electronic engineers).
And also:
http://pml.nist.gov/spd-anthology/files/Surges_happen!.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

Both guides are from reliable sources.

The IEEE surge guide is more technical.

A friend recently had her audio system damaged from an AC Power Surge.

Would like to prevent this so Googled using AC Power Surge Protection and found "The Best Surge Protector by Brent Butterworth.
http://thewirecutter.com/reviews/best-surge-protector/

I wouldn't rely on the testing that was done. There are standard tests
for surge protectors - 600V is not one of them (6,000V is). And I have
no idea if their test is representative of a surge. There is related
information on UL testing in the IEEE surge guide under "2.2.3 Surge
Limiting Voltage"

Read link "Surge Protectors ??? (Brickwall, Zero Surge, Furman, SurgeX," http://www.avsforum.com/forum/40-oled-technology-flat-panels-general/1146963-surge-protectors-brickwall-zero-surge-furman-surgex-etc.html

The vast majority of surge protectors use MOVs as the voltage limiting
element (over 90% according to the IEEE surge guide). These protectors
do not use MOVs. I have not seen them evaluated by a reliable
independent agency, and I would not use them. They, of course, claim to
be better than the MOV based ones. Some of their arguments are downright
stupid.

Then did a Forum search and found some very long discussions such as:
Surge Protectors https://groups.google.com/forum/#!searchin/sci.electronics.repair/AC$20Power$20Surge$20Protection%7Csort:relevance/sci.electronics.repair/mkLpyahIKNk/3GvjxW9LrrsJ

Westom is an internet nut that googles for "surge" to spread his ideas
about protection. He has joined an astonishing number of forums to
spread his ideas. Some of them are good, some not-so-good, and some are
complete nonsense. Everything he says about plug-in protectors is
complete nonsense. How can you tell? Westom says plug in protectors
don't work. Both the IEEE and NIST guides say they are effective.

I am "bud". I got tired of westom's crap after seeing it on several
Usenet groups I watch over a short period. I have nothing to do with the
surge protection industry other than I am using a couple protectors. A
lot of what I wrote here comes from the IEEE and NIST surge guides

Surge protector fuse blown https://groups.google.com/forum/#!searchin/sci.electronics.repair/AC$20Power$20Surge$20Protection%7Csort:relevance/sci.electronics.repair/iUffPhXZsNA/Ay8058Ba46QJ

w_tom is a name that westom used to use. More nonsense.

I have not read either of these threads.

I do not have a technical background so would be interested in others comments concerning all this.

Would like to use your advice to build a cost effective audio protection system.

Thanks

Ken

If using a plug-in protector all interconnected equipment needs to be
connected to the same protector. External connections, like coax also
must go through the protector. As explained in the IEEE surge guide
(starting page 30) plug-in protectors work primarily by limiting the
voltage from each wire to the ground at the protector. To do that all
wires must go through the protector.

The NIST surge guide suggests most equipment damage is from high voltage
between power and signal (phone, cable,...) wires. Computer and video
equipment is likely more at risk than audio. And it depends on where you
are. Some parts of the US have significant surge exposure. The major
cause of damaging surges is lightning. Normal and abnormal utility
operations can also cause damaging surges.

The author of the NIST surge guide looked at the surge current that
might come in on power wiring (US). The source was a 100,000A lightning
strike to a utility pole adjacent to a house with typical urban overhead
power distribution. Only 5% of strikes are more powerful and this is,
for practical purposes, the worst case. The surge current was 10,000A
per wire. Service panel protectors with much higher ratings are readily
available. High ratings mean long life. A service panel protector is
likely to protect anything connected only to power wiring (most audio
systems?)

The author of the NIST surge guide also investigated how much energy
might be absorbed in a MOV in a plug-in protector. Branch circuits were
10m and longer, and the surge on incoming power wires was up to 10,000A
(wort case, as above). The maximum energy at the MOV was a surprisingly
small 35 joules. In 13 of 15 cases it was 1 joule or less. There are a
couple simple reasons the energy is so low (one of which may be
particular to US wiring). Any UL listed protector in the US will have
ratings higher than that, and much higher ratings are readily available
(as in your first link). Again high ratings mean long life.

(Neither service panel or plug-in protectors protect by absorbing a
surge. They do absorb some energy in the process of protecting. And
protection from a direct strike to a building requires lightning rods.)

In the US, since 1998 UL has required thermal disconnects for
overheating MOVs. (With world markets they are probably included by all
competent manufacturers everywhere.) APC had an engineering error
resulting in a recall.

The IEEE surge guide describes how the protected equipment can be
connected across the MOVs, or be connected across the incoming power
wires. If connected across the MOVs, the protected equipment will be
disconnected on failure. (That is one reason why manufacturers can have
protected equipment warranties.) I think the IEEE surge guide says UL
requires protectors to state if they do not disconnect the protected
load with the MOVs.)

It would be nice if you could compare protectors based on joule rating.
The IEEE surge guide explains that (US) there is not a standard way of
measuring this, so some manufacturers have misleading ratings. Some
other (reliable) manufacturers responded by not including joule ratings.

 

[Phil Allison]

Cydrome Leader wrote:

KenO wrote:

A friend recently had her audio system damaged from an AC Power Surge.


** AC power voltage surges damaging audio gear are so rare that I cannot accept it as true without convincing evidence.

The DC power supply inside each piece of audio gear usually contains a transformer, rectifier and filter electros - a combination that eliminates AC voltage spikes/surges better than anything you can possibly buy or build.

That may be true if the stereo or whatever is not attached to other
devices. Once you connect things together, damage from power surges starts
to happen.

** My comments were intended to exclude the effects of a lightning strikes hitting the ground.

AC supply voltage spikes are normally caused by inductive loads going on and off.

OTOH, the term "power surge" is regularly used to explain away sudden failures in almost any electronic device - when the real cause is simply a bad component.

power surges and the damage they cause are very real problems.

** If by 'power surge' you actually you mean lightning strike.




.... Phil

 

[Phil Allison]

bud-- wrote:

As explained in the IEEE surge guide
(starting page 30) plug-in protectors work primarily by limiting the
voltage from each wire to the ground at the protector.

** Connecting MOVs to ground like that in a *plug-in device* is prohibited on safety grounds under EU and similar regulations as followed in most 230/240 V places - like Australia where I am.

MOVs either have or can develop after some use leakage currents well in excess of the maximum permitted, which is only a milliamp or so for most categories of appliances.

The only components that may be so connected are agency approved " Y caps " with values like 4.7nF - while MOVs and " X caps" always go across the line.



.... Phil