When the surge protection LED on a power strip won't light, is it likely to be a blown varistor?
My *&^#$(*&@ Belkin unit (that I paid way too much for) isn't in protection mode anymore, and I don't want to have to send it away for weeks to get a repair.
Thanks
-Markus
Best speak to your local dealer , I cant remember the last time I heard of one being damaged , all the gear is ok ?
Seems to be
Markus
Indicator does not report what you assumed. For example, notice that MOVs can even be removed and indicator lamps declares a protector as still good:
MOVs that fail so catastrophically as to cause a light change mean the design was grossly and unacceptablely undersized. Effective protectors degrade as defined by numbers in manufacturer datasheets - do not vaporize and do not cause that fuse to open. But Belkin is not selling effective protection.
How to identify an ineffective protector: 1) no dedicated earthing wire and 2) manufacturer avoids all discussion about earthing. Meanwhile look at its numerical specifications (and not the subjective propaganda). Where is each transient type listed with numbers that define protection? No such numbers exist because protectors without earthing hope you don't learn what is necessary for effective protection.
They will not even define what that lamp reports so that other will promote myths based upon no facts. Those scary pictures with all MOVs removed should start you asking embarrassing questions - such as how do protectors degrade and why is a vaporized protector not effective protection.
"Markus" wrote in message news:edijc6$s4l$ snipped-for-privacy@news-01.bur.connect.com.au...
The LED indicator shows that a Thermal Fuse (which is wired in series with the MOV) Has failed. This Thermal fuse is there to protect against the MOV becoming Leaky (Degraded) and breaking down at the rated Voltage (240V) - when this happens the MOV dissipates way more power (i.e. over a couple of watts) than it is designed to and becomes a Fire hazard. in other words the Thermal fuse failing indicates that the MOV has failed.
MOV Failure is normal - it happens - hopefully it holds on long enough to provide some sort of protection - usually it just joins the list of failed components following a Direct or near strike.
This is why charlatans* like the Links w_tom has given can show pictures of surge arrestors with the MOVs removed and the 'Protection working' LED still lit - because the LED does not show the presence of the MOV but rather that the Thermal fuse that stops the MOV causing a fire is intact.
btw it is safer to ignore most Ravings from w_tom who although he seems strangely attracted to the subject of Surge arrestors, seems to know almost nothing about the subject (as demonstrated by his lack of understanding of how/why the 'Protection working' indicator functions). I find it Ironic that w_tom has linked to a site that points out the Failings of MOVs when he has spent so long defending them ;-) It is also Interesting to note that where w_tom has spent so long bagging out anything other than 'whole house protection' he is now linking to the site of a manufacturer who makes plug in protection.
Unless you are in an area highly prone to Surges with little multiple mains earthing (i.e. a Rural area) then MOV based protection typically provides no real extra protection than the MEN Mains distribution system already offers.
The Surge arrestor industry is based on Hype and Hysteria for example you will note that Surge arrestors are rated for 8/20 uS whereas a real Lightning strike (single stroke) Lasts typically 4 or 5 times this long and usually consists of several Strokes - no MOV built can withstand a Direct or Near strike without frying itself and allowing damage to the equipment supposedly protected by it.
a Surge arrestor should be considered line of last resort protection only and should not replace common sense such as unplugging valuable equipment when a storm threatens - I have seen to many computer and Data comms installations damaged by Lightning (many of which had 'surge arrestors') to give equipment in a near or direct strike a snowballs chance in hell of surviving. Ironically most Lightning damage that I have seen to Computer installations comes not from the M.E.N AC Mains - which contrary to popular belief is in fact extremely well earthed but through phone and data lines and Radio aerials this is for two reasons: 1) Because the Multiple Earthed Neutral System provides the best Earth you are likely to get without an Extensive (and expensive) Earthing system covering half an Acre or more.
2) Because Under ground phones lines are in fact very susceptible to Earth Potential Rise in the event of a Lightning strike and are actually more prone to Lightning damage being buried.So the moral of the story is unplug your Modem from the phone line when it is not in use and unplug from the AC mains if a Lightning storm is approaching.
Regards Richard Freeman
If Richard Freeman had consulted MOV manufacturer datasheets, he would learn that MOV failure by vaporizing is completely unacceptable. Vaporizaton is not even listed in those charts for life expectancy. MOVs fail by degrading. Manufacturers provide charts with relationships of pulse times, current, and number of pulses. When an MOV's Vb voltage changes 10%, then an MOV has degraded excessively. Notice after so many transients, the MOV only degrades so much as to require replacement. Vaporization does not occur. It means Richard first consults datasheets before he somehow knows. He did not.
We do what Richard Freeman cannot. Using numbers from an MOV manufacturer datasheet, a 240 volt MOV has a curve that ends at 900 volts for highest currents. Currents well beyond those charts mean vaporization - possible fire. We know from charts that this MOV will safely shunt up to 5000 amps. What happens when a surge is a typical
10,000 or 20,000 amps? MOV voltage rises somewhere well above 900 volts. IOW appliance is exposed to well over 900 volts because MOV was grossly undersized - and also vaporized. Richard called that effective protection.If that MOV was properly sized, then voltage would never rise that high and MOV would not vaporize. But then this post uses numbers from manufacturer datasheets; not rumors that so often promote grossly undersized protectors.
MOV protectors that vaporize (and change that indicator lamp) are grossly undersized. After so many fires, protectors now have thermal fuses as a final safety device to disconnect the MOV. Only disconnects the MOV. The appliance is left connected and exposed to the surge. Thermal fuse does not disconnect an adjacent appliance. What kind of protection is that? Grossly undersized and ineffective. But that MOV vaporization does get the naive to recommend and buy more grossly undersized protectors. Notice what Richard Freeman has just recommended.
A surge too small to overwhelm an adjacent computer can vaporize a grossly undersized protector. Then the naive declares, "My protector sacrificed itself to save my computer." In reality, the computer saved itself. But the naive will recommend that grossly undersized and overpriced protector because its MOV vaporized - potentially could have created a house fire. Where does that be an honest recommendation?
Reference to
That thermal fuse is a last backup layer of protection. Why would you buy a protector so grossly undersized as to routinely depend on that thermal fuse (backup protection)? Richard Freeman says protection from a backup protection function is normal. View the scary pictures to appreciate why Richard Freeman would disparage this poster rather than post numbers from datasheets.
I think you are both missing the point re MOV's. Considering most equipment these days uses SMPS with MOV built in, the equipment itself can usually survive minor surges (ie, like spikes from the washing machine solenoids etc), however I think you will find the common misconception is that a MOV wil protect you from a lightning strike, and I think thats what most people beleive.
So what you should tell the OP is that if he wants real surge protection from old mate crashing his car into power pole and 3.3kv falling onto 110/220v lines, then go buy a commercial online UPS with a good isolation spec.
If the OP wants lighting protection, then follow Freemans advice and pull the plug when a storm is coming, because I can assure the OP will not want to pay for real lightning surge protection.
The best information I have seen on surge protection is at
- w_tom provided the link to this guide
- the title is "How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits"
- it was published by the IEEE in 2005
- the IEEE is the dominant organization of electrical and electronic engineers in the US
A second guide is
- this is the "NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home"
- it is published by the National Institute of Standards and Technology, the US government agency formerly called the National Bureau of Standards
- it was published in 2001
Both guides were intended for wide distribution to the general public to explain surges and how to protect against them. The IEEE guide was targeted at people who have some (not much) technical background.
Both say plug-in surge suppressors are effective. They protect primarily by CLAMPING all wires (including phone, ...) to a common ground at the surge suppressor, NOT EARTHING.
One (or both?) of the guides show that the protected load may, or may not, be disconnected if a MOV is disconnected. There are advantages both ways and one should decide accordingly, What indicator lights mean varies with manufacturer.
bud--
Once MOVs were installed in appliances. For example Apple II contained MOVs. No longer. MOVs were too close to transistors, too far from earth, and too undersized.
Electronic appliances contain internal protection which is why minor transients are irrelevant even to dimmer switches and smoke detectors. But a major transient such as lightning may overwhelm internal appliance protection. So we eliminate such transients where utilities enter the building; less than 10 foot to earth. Effective 'whole house' surge protection so that protection inside appliances is not overwhelmed.
Disconnecting a plug is too unreliable. Humans are not available every minute of every year to pull the plug - far too unreliable. Wall receptacles have limited number of dsconnections. Meanwhile a 'whole house' protector concept has been providing effective protection even to telephone COs (switching computers) for longer than any reader has existed. Technology is that well proven and that standard where direct lightning strikes cause no damage. Does a telco, connected to overhead wires everywhere in town, disconnect their $multi-million computer to protect it from lightning? Of course not. How often are you without telephone service for four days because lightning destroyed that computer? Never. 'Whole house' type protection means telephones work without damage during every thunderstorm. Effective protection is that well proven. Earthing before transients can enter the building.
Protectors sold for less than $50 > I think you are both missing the point re MOV's. Considering most
Look I do not reply directly to w_tom nowadays as he/she/it is so full of crap that he/she/it makes an unflushed public lavatory look pristine. however if someone makes the mistake of giving w_tom a reply I will find it necesary to insert corrections. So corrections to w_toms ravings below....
As per usual when w_tom has lost the argument he starts misquoting my post .... w_toms link talked about vaporised MOVs - I talked about degrading, then burning MOVs different kettle of fish entirely.....
- ironically this is kind of also what w_tom is talking about (however since he is completely ignorant of the subject w_tom does not realise this)
- it all comes down to the definition of the term "degradation" the IAEI however do have an article on the subject at
- let me quote the pertinent sentences :
"When MOVs degrade they become more conductive after they have been stressed by either continuous current or surge current."
and
"The degradation manifests itself as an increase in idle current at the maximum normal operating voltage in the system. Excessive idle current during normal, steady-state operation will cause heating in the varistor. Because the varistor has a negative temperature coefficient, the current will increase as the varistor becomes hotter. Thermal runaway may occur, with consequent failure of the varistor."
What this means is that a Degraded MOV is going to Start conducting current, and as those of us who know basic physics will realise this means that the MOV will heat up and ultimately become a Fire hazard.
This BTW is what happened to Markus's surge arrestor the MOV would have degraded then the Thermal fuse would have tripped.
To stop the surge arrestor becoming a fire hazard they typically have a Thermal fuse inside which will disconnect the MOV when it heats up. In order to let the user know that the has happened the manufacturer does one of two things:
1) wire a light across the MOV so that when the Thermal fuse is intact the Light is on - as a 'protection working' indicator 2) wire a light across the thermal fuse so when the fuse goes open the light comes on and warns the user that the surge arrestor needs to be replacedIf w_tom had the slightest clue what he was talking about he would have realised this.
I have to admit though that I have seen plenty of vapourised MOVs following Lightning strikes - maybe w_tom could suggest a MOV that would not suffer serious damage in a Lightning strike (I know he used to talk about 1KJ MOVs) - he does not. because he knows he cannot. They are all prone to failure in a near or direct strike not surprisng really with a typical Lightning strike
I note that w_tom has not referenced the Data-sheet - he must be making this up again! altough I note that he fails to discuss the slow response times of MOVs. And of course he also fails to mention that for all MOVs the voltage across them rises as the current through them increases - this is not linear as with a resistor but MOVs are not perfect clamps either
More evidence that w_tom knows he has lost the argument so again he misquotes me I have never ever claimed that MOVs were adequate or effective protection! - quite the contrary I have always claimed that they should be considered ' line of last resort' protection only - ie better than nothing but in the scheme of things unlikely to provide better protection than nothing.
Ah well this is merest fantasy when you bear in mind that a typical strike is several strokes lasting 20/100uS (20uS rise/peak and 100uS follow on) in the order 30,000-50,000 Amps per stroke although up to 150,000 Amps is not uncommon and 500,000,000 to 1,000,000,000 Joules typically per stroke it is difficult to imagine a 20,000 Amp at 1,000 Joule MOV Rated to last 8/20uS being worth considering.....
or degraded and trying to clamp AC mains unrealistically low ..... In fact all MOVs will ultimately degrade I do not care how big they are it is in the nature of a MOV to degrade!
At Last !!!! w_tom gets something right !!!!!! (but only because I pointed it out and it obvious from the rest of his claims he does not understand this point)
Yes Please! Note what Richard Freeman has/has not recommended .... Once again w_tom is clutching at straws I did not recommend MOV based protection as anything other than LOLR
Routinely ????? the thermal fuse trips once and that is that! next trip will lead us to the deep fried stench of computer equipment.....
Read the misrepresentations from a BS site to understand why I believe the surge protection industry is full of crap! I disparage w_tom because he is full of crap and pushes a naive and dangerous view that MOVs protect against Lightning - they do not protect adequately against near or direct strikes!!!
Well actually that pretty well is the point I am making - that a MOV does not protect against Lightning Strikes. I have seen way to much Lightning damage to suffer from that belief.
Actually a one to one isolation Transformer - particularly a Toroid with a Circuit breaker does a pretty good Job in this regard and protects against most other spikes and surges as well ....
Damn right !
Especially not the extensive Earth system required for that - and even then Lightning damage can and will occur to even the best protected installations - I have seen damage in Telephone exchanges (and they are as well protected as you can get) and Radio (and TV) Transmitters.
Regards Richard Freeman
Because effective protection is so easily implemented, then no reason to disconnect anything for protection. That fact has been demonstrated by every telephone switching station for generations and in direct contradiction to what Richard Freeman has posted. Will effective residential protection be 100% perfect? Of course not. But when destructive surges occur typically once every eight years and since minimally effective protection eliminates well over 90% of the threat, then disconnecting for protection is clearly a misguided recommendation.
Richard provides a good IAEI article on MOVs - the fundamental component in most surge protectors. In direct contradiction to Richard's claim, that article defines degadation and vaporization separately. Three failure modes are defined:
Failure (1) becomes failure (2) according to the Note. Failure (2) is MOV vaporizing (either partially or wholly). Failure (1) leads to failure (2) and vaporization. Neither failure is acceptable. A failure so problematic as to be demonstrated by numerous scary pictures from multiple sources (posted previously), and so unacceptable that industry standards were created to avoid resulting fires (ie UL1449).
In direct contradiction to Richard Freeman, failure (1) and (2) are unacceptable, are conditions beyond what the MOV manufacturer intended, and are a threat to human life. A danger so unacceptable that a thermal fuse is now installed as a last layer of human protection. Failure (1) and (2) also means an adjacent appliance is left to protect itself from well over 900 volts as an undersized MOV vaporizes.
Failure (3) is degradation - a slow change of MOV parameters. Degradation is definitely not as Richard misrepresents. Richard intentionally misrepresents his own citation by changing the definition of degradation. He speculates:
Richard defined vaporization as degradation. This will be demonstrated as wrong five times over. However, you may skip to the Fourth quote to appreciate how wrong Richard is. First, manufacturer's datasheet (and multiple following quotes) defines degradation differently:
Second, a degraded MOV is not vaporized. Degradation means a change of threshold or let-through voltage. MOV remains functional. Richard's own citation says same:
The MOV remains functional with grain size changed. This means a still functonal MOV has a changed voltage (Vb). MOV defined by IAEI remains functional in total agreement with quote from MOV manufacturer datasheet. After 10,000 impulses, its Vb voltage changes 10% - degraded but still functional. No vaporization because vaporization is not an acceptable failure mode - in direct contradiction to what Richard Freeman posts.
Third, requoting exactly what Richard quoted from the IEAI article:
Again correct. MOV only degraded; its Vb voltage changed 10%. Why a measurable 10% voltage change? Because a degraded MOV does not vaporize and may be tested with more impulses.
Fourth, another quote from Richard Freeman's own IAEI article (entitled Metal Oxide Varistor Degradation):
This time, Richard's own article bluntly contradicts his speculations. No wonder he must post insults - hoping you don't read the IEAI article that, instead, confirms posts from w_tom.
Fifth, and Richard Freeman was that much in error: consult an application note from another MOV manufacturer: Littelfuse and their application note AN9772:
Why do grossly undersized power strips fail the same way? Need I repeat the obvious: grossly undersized? That short circuit or resulting open circuit occurs "when subjected to surges beyond their peak ... ratings". This happens to grossly undersized (ineffective) plug-in protectors. Again, MOV operated well beyond its "peak current/energy ratings."
Unfortunately one here learned only from what retail store shelves - where grossly undersized protectors are sold. When confronted by numbers from manufacturer datasheets, quotes from IAEI article, or from application note from an MOV manufacturer, then Richard must attack (insult) the messenger. Richard will not reply directly. He did not learn the technology. Therefore he must insult w_tom in a hope that lurkers will neither learn the technology nor read his own cited IEAI article at:
Apparently he has never read an MOV datasheet and therefore cannot challenge the numbers. So Richard responds with another insult:
Acceptable failure mode for MOVs is degradation - change of grain size and therefore 10% change of voltage. MOV remains functional, only degrades. Catastrophic failure - vaporization - is a totally unacceptable failure mode. Power strip protectors, often grossly undersized, fail catastrophically. Undersized MOV fails by vaporizing
- not by acceptable degradati> Look I do not reply directly to w_tom nowadays as he/she/it is so full of
Evidence that w_tom knows nothing about Telecommunications and has never worked in the industry.
I on the other hand have worked in Data communications for over 20 Years and can assure you that contrary to w_toms fantasy world - In the real World damage can and does occur to equipment in Telephone exchanges - I have seen equipment damaged by Lightning located in Telephone exchanges and this is despite some of the best and most extensive protection available. Likewise w_tom also likes holding up Radio Transmitters as another fine example of 'Lightning proof installations' however again Radio and TV Transmitters are also damaged by Lightning.
Ironically MOVs are not considered anywhere near reliable enough or Fast enough for use in Telecommunications equipment and Gas Discharge Arrestors and Transzorbs (Semi-conductor spike supression - look it up) are usually used in combination with a High(ish) Series impedance to the Line - but then w_tom would have difficulty understanding this Technique and this is not applicable for use in Low impedance systems such as AC mains distribution.
bottom line is that anyone who makes claims of 100% protection from Lightning is merely demonstrating their total complete and absolute ignorance of the subject
Nope disconnecting for Protection is the only 100% effective protection
As per usual when w_tom has lost the Argument and is making himself look a fool he resorts to Lies and misquoting my posts once more for the dummies let me repeat myself : "w_toms link talked about vaporised MOVs - I talked about degrading, then burning MOVs different kettle of fish entirely....."
Note that I said that I Talked about degrading (then burning) MOVs - I did not say if the article did or not and in point of fact I have NOT even stated that MOVs do not vaporise - I have seen them with the living $#!| blown out of them (effectively vaporised) however the most common Failure mode for a MOV is that it Degrades and goes into Thermal runaway.
Further more Despite w_toms claims the Article in question does not use the term vaporisation (or even the American ? spelling Vaporization) It talks about the usual Failure modes (many of which lead to self incineration ....) and I quote "The significant MOV failure mechanisms include: electrical puncture, thermal cracking, and thermal runaway" So once again w_tom lies and misquotes an Article.
In actual fact I pointed to the article for a definition of the term degraded which w_tom was bandying about in a way that made it obvious he did not understand the term - degradation ultimately results in the Destruction of the MOV. w_tom pretends it is some kind of loss of effectiveness of the MOV only.
w_tom adding his own words in an effort to win an argument that did not exist until w_tom invented it this is not a quote from the article this is w_tom paraphrasing - the MOV burns at 1 leading to 2 - however he has also missed the MOV degades definition.
once again w_tom misquotes I never stated that this was acceptable - this is just w_toms fruitcake fantasy and In fact I pointed out that MOVs required thermal Fuses to protect against these Failures - w_tom pretended that MOVs do not fail in this mode.
w_tom talks glibly about undersized MOVs - problem is he cannot name any that will withstand a near or direct strike - for the simple reason that there are none.
It is obvious that w_tom has not taken the Time to read the link I referenced - as it was this link that defined Degradation not me.
As per usual when w_tom is shown wrong he carefully avoids the quote from the article so he misquotes me and straight out lies - I guess he is so used to spouting crap that he does not even notice that he is lying.
Let me quote directly from the Article that w_tom is having so much trouble understanding :
"When MOVs degrade they become more conductive "
Pretty clear eh? - except to a moron like w_tom
Well actually I never mentioned the MOV vaporising - what I did show was how degredation led to the overheating and incineration of the MOV
"When MOVs degrade they become more conductive " then "the MOV draws in excess of 1 mA of current during each half-cycle of the sine wave voltage, a condition tantamount to thermal runaway"
But then I wouldnt expect w_tom to understand a simple concept like Thermal runaway - or how this leads to the destruction of the MOV
selective quoting where he carefully avoids the point I was making
"When MOVs degrade they become more conductive " then "the MOV draws in excess of 1 mA of current during each half-cycle of the sine wave voltage, a condition tantamount to thermal runaway"
Again more fantsy from w_tom about vaporisation
But w_tom carefully avoids the result of this increase in conductivity and how this leads to thermal runaway and the destruction of the MOV "the MOV draws in excess of 1 mA of current during each half-cycle of the sine wave voltage, a condition tantamount to thermal runaway"
"When MOVs degrade they become more conductive " then "the MOV draws in excess of 1 mA of current during each half-cycle of the sine wave voltage, a condition tantamount to thermal runaway"
Please w_tom you cretin read the Article - read it slowly, Take time to understand it, Take time to think about Leakage current and Thermal runaway
No wonder w_tom resorts to posting lies - hoping you don't read what has really been written in the article and how it explains what degradation is and how it leads to the destruction of the MOV
I dont know why w_tom is quoting this as it goes against his argument that MOVs degrade in some kind of unexplained mode that does not result in incineration of the MOV
Maybe he is just off his scone and thoroughly confused and needs a good lie down ??? - how does this match w_toms earlier claim : "Because a degraded MOV does not vaporize and may be tested with more impulses." - a short circuited mov will certainly get rather hot if connected to AC mains
Goodness I dont even need to try to point out how wrong he is he does it himself ;-)
what w_tom is avoiding mentioning here is that all surge arrestors will be exposed "to surges beyond their peak ... ratings" in a near or direct strike
when confronted by Data and quotes from IAEI article w_tom invents things and tells lies as per usual...
w_tom does not quote Data sheets because he cannot find one for a MOV that will withstand a near or direct strike and that I will hold it up for ridicule. He knows that any Data sheet he finds will be easily shown to be seriously incapable of withstanding a near or direct strike so he just pretends or makes stuff up as usual.
quoting again from the IAEI article: "When MOVs degrade they become more conductive " then "the MOV draws in excess of 1 mA of current during each half-cycle of the sine wave voltage, a condition tantamount to thermal runaway"
Catastrophic Failure is ultimately the normal Failure mode for a MOV because:
"When MOVs degrade they become more conductive " then "the MOV draws in excess of 1 mA of current during each half-cycle of the sine wave voltage, a condition tantamount to thermal runaway"
But remember Folks what Degradation is (according to the IAEI article): "When MOVs degrade they become more conductive " then "the MOV draws in excess of 1 mA of current during each half-cycle of the sine wave voltage, a condition tantamount to thermal runaway"
Well actually all this in complete support of what I said and in complete contradiction to w_toms fantasy world
Yep lets see what the IAEI article has to say on degradation again : "When MOVs degrade they become more conductive " then "the MOV draws in excess of 1 mA of current during each half-cycle of the sine wave voltage, a condition tantamount to thermal runaway"
What is w_tom on about ???
- he has this fantasy that bigger MOVs do not heat up when they Fail - is this supported by manufacturers data sheets ? Nope all MOVs Degrade and what happens to a MOV when it Degrades again?
"When MOVs degrade they become more conductive " then "the MOV draws in excess of 1 mA of current during each half-cycle of the sine wave voltage, a condition tantamount to thermal runaway"
That's Right they become more conductive then they heat up and Go into Thermal Runaway - more Detail from that IAEI article that w_tom completely Fails to understand:
"MOVs degrade gradually when subjected to surge currents above their rated capacity. The end-of-life is commonly specified when the measured varistor voltage (Vn) has changed by + 10 percent.4 MOVs usually are functional after the end-of-life, as defined. However, if an MOV experiences sequential surge events, each causing an additional 10 percent reduction of Vn, the MOV may soon reach a Vn level below the peak recurring value for the applied Vrms. When this state is reached the MOV draws in excess of 1 mA of current during each half-cycle of the sine wave voltage, a condition tantamount to thermal runaway. In nearly all cases, the value of Vn decreases with exposure to surge currents. The degradation manifests itself as an increase in idle current at the maximum normal operating voltage in the system. Excessive idle current during normal, steady-state operation will cause heating in the varistor. Because the varistor has a negative temperature coefficient, the current will increase as the varistor becomes hotter. Thermal runaway may occur, with consequent failure of the varistor."
So what it is saying then is that a MOV is considered by the manufacturer to have reached end of life when vn has changed by 10% unfortunately in the real world no-one actually knows when the MOV has reached this state - or does w_tom offer a vn testing service "Measure your MOVs once a week" ?
In the real world (not w_toms fantasy world) MOVs either Fail short Circuit or suffer degradation which ultimately leads them to suffering Thermal runaway and incinerating themselves - this failure mode is actually used by the Manufacturers deliberately to blow a fuse and indicate when the surge arrestor no longer offers even the minimal protection it usually does - even the big MOV based surge arrestors installed in fuse boxes (such as w_toms much loved 'whole house protection' ) contain a fuse as these MOVs also breakdown and overheat
face it w_tom you do not have a clue what you are on about ...
Richard makes more claims not based in technical reality. MOVs have long been fast enough for telecommunication protection which is why Gas Discharge Tubes (GDTs) were replaced by MOV similar devices. Because a traditional MOV has too much capacitance, then telcos manufactured an MOV similar device that was standard at homes even in 1960 North America. Protector was fast enough even that long ago. This lower capacitance version of an MOV was often called 'carbons' and is still found in many older telephone installations:
Technical fact posted even with a 1960 era example.
Traditional avalanche diodes such as transzorbs also have too much capacitance - also in direct contradiction to what Richard posts. The carbons have been obsoleted by other semiconductor based protection; again manufactured so that capacitance is lower. If Richard knew technical facts, then he would have known that transzorbs have too much capacitance:
Unlike other regions, North American telcos have routinely installed effective protection on their customer's subscriber lines; now installed in a box called the NID. North American electrical codes even define how this telephone protector must be earthed. Australian should upgrade their telephone installations with the most important component in transistor protection: earthing.
Now Richard claims MOVs are too slow for telephone line protection. How silly. He does not even know of MOV like protectors that were standard as telephone line protection even in the 1960s - and since obsoleted by semiconductor protectors. Somehow a nanosecond response time is too slow? But again, Richard posts attacks; does not know basic technology. He even assumed MOVs are too slow without first learning what has been standard for generations.
North America has been installing properly earthed protectors on customer phone lines as long as any lurker can even remember. Protection that has not been standard in so many other countries AND is necessary in any building that contains transistors. The lurker is warned of those who post with acidity and who don't even know that MOVs are more than fast enough. Richard does not even know of THE most critical component in any protection system - single point earth ground.
LED on a power strip can report a defective protector. It does not report a protector as good or effective. To sell power strip protectors on myths, the manufacturer is even vague about what that light reports. Consumer is cautioned about power strip protectors that have some nasty side effects as demonstrated by scary pictures in:
The lurker is also reminded how some recommending plug-in protectors also use insult as technical proof.
How to identify ineffective protectors: 1) it has no dedicated wire for that 'less than 3 meter' connection to earth, and 2) its manufacturer avoids all discussion about earthing.
Better protection, standard even in telco switching centers, earths before transients can enter a building. One 'whole house' protector for every appliance verses maybe 50 or 100 plug-in protectors. Effective protection costs maybe one dollar per protected appliance AND does not leave a homeowner worried about scary pictures:
Once again when w_tom is incapable of arguing a point he makes up Facts by showing a Picture of something dating Back to the 1960's - what this thing is I could not say - but it is definitely not a Line module of any sort out of a modern exchange and certainly nowhere near small enough to fit in say a modern DSLAM besides this is all pretty well irrelevant - at work we use Marconi, Nokia (European I know) equipment which use clamping Diodes and Adtran (North American) which again use semiconductor diodes for Protection and I will have to have a look at the Stratacom/Cisco gear on Monday again I bet it is all semiconductor based - not a MOV in sight - contrary to w_tom's claims.
- the main issue here is reliability (w_tom of course side tracks to the speed of the device since he knows that he cannot argue that the MOV is more reliable than a Transorb -BTW the MOV actually is slower than the transzorb - again another fact that w_tom does not dispute because he knows he cannot)
Now I know what w_tom will say that This North American Telco protection is so fantastic, blah blah blah that Telco gear in the US never suffers from Lightning damage and it would only happen in Australia - that is funny as this is not the experience of Ron Potee Interim Director of IT for Public schools in Huntsville Alabama in this document :
and I wonder why
strange they work then even on ADSL2+ services
Hang on now one minute you are claiming it is all MOV based and now you are saying that "Carbons" or MOVs have been made obsolete and that it is Diode based protection nowadays ? - how w_tom twists and turns when he is on the hook and being shown up as being full of crap.
Hang on you are referencing an Application note which tells you how to choose the right TVS for your application as proof of what ??? that they are used in High speed data services ?
The whole point of this app note to advise the engineer on how to choose the right TVS for their high-speed data applicationfrom ISDN BRI through to Fast Ethernet (100Mbs) In fact this App note supports my claim that they are used in High speed data Services.
What were you hoping that no-one would actually read the app note ??????
So here we find w_tom again misquoting and telling lies since he cannot actually support his argument with any real documented Facts
And North America - like every other Country that suffers Lightning still has Telco equipment damaged by Lightning - This is Fact no matter what w_tom claims here is an example of Lightning damage to exchange equipment:
and according to 'Lightning fatalities in North Carolina 1972-1988 by R.L Langley and K.A Dunn" - citing the North Carolina medical examiners office
3% of Deaths due to Lightning during 1972 - 1988 time were of People Inside a building using the Telephone. and isnt this North Carolina Place in North America also?In fact Professor Martin A Uman (probably one of the worlds leading experts on Lightning) was quoted in 1997 as saying that there were probably 100 or more injured by Lightning while using a Telephone each year in the United States (that is still North America isnt it ?) with 15-20 of these injuries being serious.
And I wonder why the National Lighning Safety Institute would bother recommending that you not use the phone during a Thunderstorm if Telco protection is 100% effective as w_tom claims ?
Further more on the NLSI website at:
then again on
but then w_tom will just ignore these Facts -as he always does with inconvenient Facts juat as he has been unable to post a link to the Data sheet for a MOV that can stand say even 1% of a Lightning strike without any problems.
Australian Lightning protection is as effective as in the USA
MOVs take time to react - the higher the initial pulse the faster they react - the lower e
Standard for generations means nothing - The Horse and cart were standard for generations - this means nothing SCDs are faster than MOVs end of statement
once again w_tom knows he has long since lost the argument so he makes claims about what I do or do not know and once again shows his complete, absolute and utter igorance of Surge protection only some one as ignorant of lightning as w_tom would imagine that a Single ground stake was anything near adequate for a Lightning strike - I guess he is not aware that a Single Earth stake will Suffer an EPR in excess of 100KV during a Lightning Strike
Dunno what his point is here - So new MOV based surge arrestors (including those that go in the switchboard for 'whole house protection') are required to have a thermal Fuse to stop a 'degraded' or blown MOV burning the House down - this is what I have been saying (and ironically w_tom has been arguing against) all along - But w_tom has long since lost this argument so he resorts to pretending it was about something else...
Once again w_tom resorts to Lies and misquoting I never recommended plug-in protectors - w_tom insults folks intelligence with the Lies and crap he posts
Any protection that claims 100% effectiveness - this is so obviously a Lie that you would have to presume the rest of the claims were a Lie also oh hange on that is what w_tom keeps claiming 100% effective protection - just more proof you cannot believe a word he says.
The lurker is again cautioned about Richard Freeman posts. For example, the transzorb is faster then an MOV. So what? They are both many times fast enough - responding in nanoseconds. He posts half truths that confuse the lurker and to attack w_tom.
Provided previously were components used in surge protection that Richard did not even know about. That point made to demonstrate how little Michael really knows about protection. Michael posts long about damage that occurred - maybe even with surge protectors installed. Again, Richard does as so many others who never learned the technology. They cite the exception and fail to first learn why that failure happened.
Protection is not just about the protector as Richard would have you believe. Knowledge of protectors is important. But damage can still result when earthing is insufficient. Richard would have you believe protection - earth ground - was sufficient when so many (such as Richard) don't even understand why earthing is so critical. Why were some on the phone harmed by lightning? Did that short connection to earth exist or was it disconnected by a naive homeowner? The lurker should be asking that same question. Is earthing for each layer of protection properly installed? Not safety ground. Earthing.
Effective protection was even standard before the 1960s when Richard Freeman said such devices were too slow. Yes, some people are harmed by talking on the telephone during a thunderstorm. Does that mean protectors are too slow? Nonsense. Telephone, emergency response, and corporate telephone operators take off headphones with each thunderstorm? Of course not. Their earthed protection is minimally sufficient - and inspected. They don't just have protectors. They have something so essential - protection - single point earth ground. What do plug-in protectors pretend is not necessary? Earthing. What does Richard not ask? Where is the earthing?
Richard Freeman did not even know of protector technology from the
1960s. This paragraph demonstrates his problem:MOV failure is directly traceable to a human who has installed grossly undersized protectors (ie many power strips and UPSes). Meanwhile effective protection uses sufficiently sized MOVs - do not vaporize. Protection is not just defined by MOVs. The most critical part of protection - the art of protection - is earthing. Routine to earth direct lightning strikes and the protector remain functional. Numbers from manufacturer and experiences even in every telephone switching center (connected to overhead wires everywhere in town) demonstrates that reality for longer than Richard has even existed.
An indicator lamp on a power strip protector can report the protector defective. But lamp cannot report a protector as good. Meanwhile, power strip protectors do not have a dedicated connection to earthing AND do not even provide numbers that claim protection. A damning fact made obvious by a necessary short and dedicated connection to single point earthing.
Michael will prove his po> ....
w_tom wriggles and squirms like a fish on a hook then resorts to telling Lies in order to pretend he has a valid point so let us work through w_toms misinformation one point at a Time.
w_tom claims that a MOV based surge arrestor can provide 100% effective protection. Unfortunately there is not a MOV manufactured that can safely handle 1% of a typical Direct Lightning strike - w_tom avoids posting links to Data sheets for MOVs because he knows that I could point out that any MOV he could find would have difficulty handling a near strike let alone a Direct strike.
w_tom claims that it is all in the Earthing.... Ironically w_tom actually speaks some truth here but what he neglects to mention is that a single Earth stake will suffer an EPR (Earth Potential Rise - I believe that in the USA this is known as GPR) of in excess of
100,000 Volts in a direct strike. w_tom does not even understand the basic physics involved for Earthing - this is why he so frequently refers to the 'Art of Earthing' because for w_tom Earthing is an art not a science. An Earth required to even begin to effectively shunt a Lightning strike with a minimum EPR requires multiple Earth stakes bonded together with low impedance cable/bussbars covering 1/4 of an Acre or more - is this practical or cost effective in a Domestic situation ? nope ! - yet w_tom still claims 100% effective 'whole house protection' for domestic premises is not only possible but inexpensive.w_tom claims that Lightning does not come in via Phone lines as all Phone lines in North America are adequately protected - this is another of his
100% Bullshit claims he then tries to squirm out and blame the home owner when presented with evidence that a high number of injuries and some deaths occour each year in North America due to folk using Telephones during Thunderstorms. Further more w_tom claims that Telephone exchanges never ever suffer lightning damage - this in direct contradiction of the experience of anyone who works in the Telecommunications industry. w_tom ignores the example provided as an inconvenient Fact.Next w_tom claims that MOVs have been adequate protection for Telephone exchanges since the 1960's - he neglects to mention that the Exchange Technology in the 1960's was mainly Relay based switching with a lot of Step-by-step (and Strowger) equipment still in use. whereas modern exchanges are primarily digital Micro-processor based and these Micro-processors running at up to 200Mhz routinely deal with Signals lasting just nano seconds. The VLSI integrated circuits used in these Exchanges are susceptible to static charges so small that a careless Tech who is not using antistatic precautions when handling the Circuit boards in the exchange can cause damage without even feeling or noticing the discharge. w_tom from his standpoint of complete and utter ignorance then asks how Spikes from Lightning lasting mere nano-seconds could not possibly cause damage.
Further more modern exchange equipment does not depend on MOVs for protection as while they may have been adequate to protect Strowger switches they are neither up to the task nor reliable enough to provide protection for modern exchange equipment so w_toms claim that lack of damage to Telephones proves the effectiveness of MOV Lightning protection is also proved False. Modern Exchanges equipment typically uses an impedance of some sort in series with the line to limit the current to managable levels then typically a Transzorb or equivalent (Transzorb is a registered Trade name of Vishay semiconductor however the term is often used to refer in a generic manner to clamping diodes used for spike supression) to clamp the surge. This though is not a techniique that can be readily adapted for use on low imedance circuits like the AC power mains.
Next w_tom claims that a decently sized MOV does not suffer degredation - again he provides no links to such a MOV's data sheet because all MOVs suffer degredation when they suffer from surges - especially surges outside the MOVs stated limits. But again w_tom knows that I can show that any MOV that he posts a link to the data sheet for will suffer degredation and possibly destruction in the event of a direct strike (and even in the event of many near strikes) so he carefully avoids this inconvenient Fact *.
w_tom also claims that degredation of a MOV does not lead to it's clamp voltage changing and the MOV becoming leaky - which leads to thermal runaway in the MOV and ultimately its destruction - this in contrary to the IAEI experiences and discussion paper on MOVs at
Finally w_tom claims that I think plug in Power protectors are effective - This is just an insult and a Blatent lie on w_toms part
Next there are some questions regarding statements that w_tom has told in the past that he has still not answered :
Tell me again tom what a Thermal Fuse is.
Tell me the fairy tale again about how Lightning is a 'Low energy event'
Identify the 'direct connection between AC mains and the Integrated circuits in a modern modem' for me.
explain how 0.6mm diameter single strand copper wire has a lower impedance than 2.5mm square multistrand copper wire and therefore provides a better earth.
Tell me again how Telco gear and TV/Radio Transmitters never ever suffer Lightning damage.
Tell me how long your 1KJ mov lasts in a Direct Lightning strike ?
how long does a surge last ? - what is the definition of a surge ?
Remind me again when the MOV was developed ?
But then again I am probably assuming w_tom understands enough basic physics to answer these questions.....
Now it would seem that w_tom is hallucinating and calling me the Arch angel Michael - but then it always was pretty obvious w_tom is completely off his Tree ;-)
Well I do not need to warn the Lurker about w_tom as it is obvious from his Posts that he does not have a clue.
w_tom has trouble understanding how Electronics that has issues with the Static charge built up on the Human body and has no trouble handling signals lasting 5 nano seconds (200Mhz) could have issues with Spikes lasting nanoseconds - just more indications of how little idea w_tom has about modern Electronics.
so again w_tom resorts to telling lies as it was I who provided alternatives and w_tom who had to quickly go and look them up.
who is Michael ??? Looks like w_tom has completely lost it .... but then it is obvious that w_tom has long ago lost it.
The point of the (many) examples of injury, Death and Damage to Telco gear were merely to highlight that w_toms claims of Nil Failure to Telco gear were like almost all w_tom's claims completely false and especially like his claim that the 'whole house protection' he installs is 100% effective.
when w_tom is proven to be incorrect he wiggles and squirms and pretends that the issue is completely different
As per usual when w_tom is shown to be wrong he invents facts to suit him - w_tom does not understand how the Surge protection could fail so he speculates - But remember it was w_tom
Because he does not have a clue w_tom tries to pretend that I was saying was that MOV protectors were to slow - Actually this is merely proof that - contrary to w_tom's claims North America does not have 100% effective protection against Lightning.
well Actually modern call Centers are all fed by Fibre optic cable - which does not conduct surges
Once again w_tom pretends that I have been saying plug in protectors work - this is a lie perpetuated by w_tom so that he has something to argue against
w_tom is still unable to provide a data sheet for a MOV that does not Degrade or one that can handle a near/direct strike so instead he pretends - he is completely unable to support this claim with any published facts - so he just makes this assertion and hopes that no one notices that as per usual
Damn ! when a reality is inconvenient w_tom just reinvents reality - experience in Telephone switching centres proves that damage can and still does occur despite the best Earthing and protection available but w_tom just chooses to ignore this and claims otherwise.
In fact the Earthing system in an Exchange is considerably more comlplex and expensive than is practical in a domestic situation as this Earthing system often involves multiple earth stakes bonded together as Experience has long shown that a Single Earth stake can suffer EPR and hence render surge protection useless in the event of a Lightning strike.
Furthermore Phone lines are a High impedance service and typical surge protection consists of an impedance in series with the Line to reduce Surge current to manageable levels and then a Protection device - typically a supression diode of some sort (be it the Vishay Semiconductor Transzorb or another brand) which clamps the incoming spike on the Line card itself.
What this means is that actually the same protection Techniques used on (relatively) High impedance Lines such as phone and data Services is not Scaleable for use on Low impedance circuits such as AC power distribution.
Further more w_tom holds up Telephone exchanges as an example of the success of MOVs but in fact Telephone Exchanges DO suffer damage and secondly Modern exchange equipment us Transzorbs not MOVs. Of the Telco equipment I have on Hand:
Modules from an ADTRAN DSLAM (North American built equipment) Octal SHDSL Card (part no 1181403L2) Line protection = ST Transil *1 Octal ADSL Card (part no 1181405L1) Line protection = ST Transil *1
Nortel DMS (Canadian - this is still North America)
2BIQ ( Basic rate) Line card Line protection = ST Transil *1Nortel DMS 100 and 300 Line cards all prove to use Spike
*1 Note Transzorb is used as a generic name for a Transient supression diode and is actually a Registered Trademark of Vishay semiconductor - Transil is ST's equivalentw_tom is so divorced from reality by now that he has even forgotten who he is dealing with - or is that Michael the arch-angel he can see after consuming waaay to many drugs ......
Richard Freeman is so divorced from *why* as to even claim that call centers use fiber optic cables. Yes? Call centers in the 1930s used fiber optics? His diatribe is chock full of such spin. Even in the
1930s, earthing where phone lines entered the building meant operators need not remove headsets during thunderstorms. Effective protection was that well proven that long ago. Protection has always been defined by earthing.Damage to telephone switching centers is so rare and so unacceptable that damage is a major news story. Connected to overhead wires everywhere in town, a switching station that suffers direct strikes every year must never suffer damage. An informed technician would have known this. Numbers for direct strikes without damage were published even in Oct 1960 by Bodel and Gresh in the Bell System Technical Journal using data from New Jersey, Georgia, Maryland, and Michigan. Effective and earthed protectors were standard that long everywhere. Hundreds of surges were detected and measures - without damage to any equipment. That is how standard protection - using earthing - has been proven. This in direct contradiction to Richard's post - that provides neither numbers nor citations.
What does a telephone switching center do so that direct lightning strikes every year do not cause damage? Every wire inside every cable is earthed via 'whole house' type protectors located best up to 50 meters distant from the $multi-million computer. In 1960, that was the MOV similar device that Richard says is too slow. That up to 50 meter separation increases protection. Since earthing is so essential, then every telephone company has long technical manuals on how earthing must be installed, upgraded, and maintained. Earthing defines protection.
By this point, every lurker should know: no earth ground means no effective protection. Richard Freeman is still posting four letter insults so that you don't learn that fact and corresponding numbers.
No earth ground means no effective protection. Earthing - as demonstrated by Ben Franklin even in 1752 - is the most essential component of a surge protection system.
I dont know what your experiece is with telco gear, nor do I know where you are getting your info from. But I suspect with your endless references to circa 1960 that you don't really understand how a modern exchange works and what gear they use. A substantial amount of info you have posted is completely incorrect. Furthermore, I notice that you keep steering the topic in a new direction with every post, which leads me to beleive that once again, you are misunderstandg the issues.
If The Real Andy could dispute what was posted, then he would have cited technical sources, provided numbers, or described engineering concepts. Instead he uses lawyer type logic. He is critical of a paper just on this subject from the Bell System Technical Journal - where real world experiences and research defined lightning protection? Andy did as he did previously. He claims multiple reasons for effective protection are wrong. He does not even acknowledge a single posted reason. He does not challenge a single number or citation. He only says tens of reasons are all wrong. One sentence again proves his point? Yes if one believes lawyer logic or politicians.
Why was a 1960 Bell System Technical Journal paper cited? Why does no one else cite a technical reference? Why did Bodle and Gresh do that research? Question was whether electronic telephone exchanges would be more susceptible to lightning damage. Question was whether well proven lightning protection from long before WWII was sufficient for transistor protection. Anyone who knows about surge protection learns from early 1900s research AND again in 1950s and 1960s research for semiconductor protection. Their first sentence:
Obviously anyone who learns surge protection would read this paper.
Learned is why (when) lightning does not damage transistors. Principles of effective protection is pre-1960 research. Those who know protection would also know why that 1960 paper is so appropriate. Effective protection is that old and well proven no matter how many times Richard Freeman posts insults and spins half truths.
Bottom line fact - protection is provided by earthing. No earth ground means no effective protection. What is the essential component in every protection system? No a power strip protector. Not a protector's indicator lamp nor MOV inside that protector. Earthing - as demonstrated by Franklin in 1752 - is the most essential protection component in every telephone CO (switching station). Even the Bodle and Gresh paper demonstrates why earthing is so critical where damage is not acceptable.
Forget the protector's LED indicator. A protector without a dedicated earthing connection AND whose manufacturer avoids all discussion about earthing: ineffective. Well, at least one poster first learned well proven technology and did this stuff. So well grounded that even Richard Freeman insults do no damage.
Note gentle reader that as per usual w_tom cannot quote my message in its entirety but snips and misquotes to make an erronous point.
First I can recycle all these points because w_tom has not really answered them (please feel free to skip past this section if you have read all this before):
w_tom claims that a MOV based surge arrestor can provide 100% effective protection. Unfortunately there is not a MOV manufactured that can safely handle 1% of a typical Direct Lightning strike - w_tom avoids posting links to Data sheets for MOVs because he knows that I could point out that any MOV he could find would have difficulty handling a near strike let alone a Direct strike.
w_tom claims that it is all in the Earthing.... Ironically w_tom actually speaks some truth here but what he neglects to mention is that a single Earth stake will suffer an EPR (Earth Potential Rise - I believe that in the USA this is known as GPR) of in excess of
100,000 Volts in a direct strike. w_tom does not even understand the basic physics involved for Earthing - this is why he so frequently refers to the 'Art of Earthing' because for w_tom Earthing is an art not a science. An Earth required to even begin to effectively shunt a Lightning strike with a minimum EPR requires multiple Earth stakes bonded together with low impedance cable/bussbars covering 1/4 of an Acre or more - is this practical or cost effective in a Domestic situation ? nope ! - yet w_tom still claims 100% effective 'whole house protection' for domestic premises is not only possible but inexpensive.w_tom claims that Lightning does not come in via Phone lines as all Phone lines in North America are adequately protected - this is another of his
100% Bullshit claims he then tries to squirm out and blame the home owner when presented with evidence that a high number of injuries and some deaths occour each year in North America due to folk using Telephones during Thunderstorms. Further more w_tom claims that Telephone exchanges never ever suffer lightning damage - this in direct contradiction of the experience of anyone who works in the Telecommunications industry. w_tom ignores the example provided as an inconvenient Fact.Next w_tom claims that MOVs have been adequate protection for Telephone exchanges since the 1960's - he neglects to mention that the Exchange Technology in the 1960's was mainly Relay based switching with a lot of Step-by-step (and Strowger) equipment still in use. whereas modern exchanges are primarily digital Micro-processor based and these Micro-processors running at up to 200Mhz routinely deal with Signals lasting just nano seconds. The VLSI integrated circuits used in these Exchanges are susceptible to static charges so small that a careless Tech who is not using antistatic precautions when handling the Circuit boards in the exchange can cause damage without even feeling or noticing the discharge. w_tom from his standpoint of complete and utter ignorance then asks how Spikes from Lightning lasting mere nano-seconds could not possibly cause damage.
Further more modern exchange equipment does not depend on MOVs for protection as while they may have been adequate to protect Strowger switches they are neither up to the task nor reliable enough to provide protection for modern exchange equipment so w_toms claim that lack of damage to Telephones proves the effectiveness of MOV Lightning protection is also proved False. Modern Exchanges equipment typically uses an impedance of some sort in series with the line to limit the current to managable levels then typically a Transzorb or equivalent (Transzorb is a registered Trade name of Vishay semiconductor however the term is often used to refer in a generic manner to clamping diodes used for spike supression) to clamp the surge. This though is not a techniique that can be readily adapted for use on low imedance circuits like the AC power mains.
Next w_tom claims that a decently sized MOV does not suffer degredation - again he provides no links to such a MOV's data sheet because all MOVs suffer degredation when they suffer from surges - especially surges outside the MOVs stated limits. But again w_tom knows that I can show that any MOV that he posts a link to the data sheet for will suffer degredation and possibly destruction in the event of a direct strike (and even in the event of many near strikes) so he carefully avoids this inconvenient Fact *.
w_tom also claims that degredation of a MOV does not lead to it's clamp voltage changing and the MOV becoming leaky - which leads to thermal runaway in the MOV and ultimately its destruction - this in contrary to the IAEI experiences and discussion paper on MOVs at
Finally w_tom claims that I think plug in Power protectors are effective - This is just an insult and a Blatent lie on w_toms part
Next there are some questions regarding statements that w_tom has told in the past that he has still not answered :
Tell me again tom what a Thermal Fuse is.
Tell me the fairy tale again about how Lightning is a 'Low energy event'
Identify the 'direct connection between AC mains and the Integrated circuits in a modern modem' for me.
explain how 0.6mm diameter single strand copper wire has a lower impedance than 2.5mm square multistrand copper wire and therefore provides a better earth.
Tell me again how Telco gear and TV/Radio Transmitters never ever suffer Lightning damage.
Tell me how long your 1KJ mov lasts in a Direct Lightning strike ?
how long does a surge last ? - what is the definition of a surge ?
Remind me again when the MOV was developed ? - I thought w_tom had finally caught on to this one and I could leave it out but the latest posting indicates otherwise
But then again I am probably assuming w_tom understands enough basic physics to answer these questions.....
************************************************************Now on with the rest of the show in which w_tom spins some more misinformation -
w_tom is so stupid he quoted what I said directly - that MODERN Call centers are fed by Fibre optic cable then he questions if call centers in the 1930's used fibre optics?
- well I dont know about other folk but I hardly consider 1930's Technology to be Modern. w_tom's Diatribe is chock full of such Lies and Misquotes that you cannot really believe a word that he writes.
Ah just when I thought that w_tom had learnt when MOVs were invented he regresses.
- As per usual w_tom misquotes and Lies in order to win points he so desperately needs - a Clue here 'w' you are about 20 Years too early if you are trying to use this to demonstrate how good MOVs are.
If you are trying to illustrate how important Earthing is well then again you are trying to squirm in another direction - I have already pointed out how important Earthing is that was never in dispute except in your mind.
What is in dispute is: Your belief in the 100% effectiveness of MOVs for Lightning protection Your belief that the lack of damage to Telephone exchanges proves that MOVs are 100% effective (especially when Exchanges do not even typically use MOVs). Your assumption that an Earthing system adequate to to absorb a Single Lightning strike without a signifcant EPR is not only feasible for the average home owner but inexpensive.
and Again w_tom shows that he knows nothing about Telecommunications and has never worked in the Industry (or has he changed his tune slightly) Lightning damage to Telephone exchanges does happen (Note I am not saying it is common merely that it does happen) - despite the best Earthing and Protection available In contradiction to w_toms continued and erroneous claims of 100% effective protection.
Next w_tom assumes that this is big News- on the contrary it is so common (Note that it is rare for a complete exchange Failure but individual Line cards etc being damaged by Lightning is not an uncommon event following a Thunderstorm) that equipment gets damaged in some way by Lightning that it hardly rates a mention in the news and sparing for this is allowed for by most sane Network engineers (Yes I do maintain a Stock of spares specifically for Lightning damage for the ADSL Network I run - a clue to the Aussies this network is currently about the third largest ADSL Network in Australia).
Lightning damage is basically a calculated risk where you do all you can to avoid it BUT it still happens from time to time as contrary to w_toms Lies there is no 100% effective Lightning protection available and it is the cost of doing business like all other failures in the Telco game (Back-hoe fade etc ).
Must have been a damn thin issue of the Bell system Technical Journal In October 1960!
Because we go from Volume 39 Issue 5 In September of 1960 which has the contributer acknowledgements starting page 1379 to the Next article ("Signalling Systems for the control of Telephone switching") in Volume 39 Issue 6 starting page 1381 on November 1960.
It looks suspiciously like they did not publish a Bell System Technical guide in October 1960!
Ooops have I just caught w_tom out in yet another lie ....
Remind me again what Technology the Exchanges used in the 1960's ? w_tom extraoplates that Because Strowger gear was less susceptible to Surges and Lightning damage therefore modern computerised exchanges are also.
Hang on Computer based exchanges in 1960 ??? - there may have been one or two but they were hardly common then.
well actually w_tom is incorrect again. MOVs may have been used in the
1960's for Strowger exchanges but the Carbon block arrestor that he claims in an earlier post was a MOV is actually a spark gap and this type of arrestor also often included fuses or 'Heat coils'.- once again because w_tom knows nothing about Telecommuncations he just invented a few more facts to suit himself....
Gas discharge Tubes are generally used nowadays in Telephone exchanges if/when surge supression is installed at the MDF (actually common in small country exchanges) with semiconductor diodes (aka Transils, Transzorbs) used on the Line cards themselves - Note Gas discharge tubes are unsuitable for use on AC Mains which is why w_tom cannot rave on about them (just watch - w_tom will devote the next post to why Gas discharge tubes are unsuitable for Mains use and then pretend I said they were).
He gets sooooo close and then misses the point entirely - geez if he had a brain he would have worked it all out long ago. This is mainly due to the way an Exchange is set up but effectively presents some Series impedance - which was a point I raised.
Well of course when w_tom says enough crap he has toget something right eventually - Note though that he carefully avoids my statement that Earthing was critical and where I pointed out that a Single Earth stake was woefully inadequate to handle a lightning strike.
- but w_tom has been unable to answer any of the points I raised last post so instead he makes up points he can answer
w_tom is is not a real name and is therefore an annonymous poster who goes to great effort to hide who he is whereas I am a real person and use my real name. This is because at the end of the day w_tom is not prepared to stand behind his advice.
Well w_tom does not quote facts, Numbers or even genuine articles as he knows that they can all be shot down in flames So lets try a few of our own:
a Good ground resistance for a single earth stake is considered to be 5-10 Ohms the current in a typical Lightning strike is 30,000 to over 200,000 Amps Lets take the lowest Figures of 5 Ohms at 30,000 Amps
5*30,000 gives us an EPR of 150,000 Voltswhat this means is that in the event of Lightning being shunted to the Earth stake then the Earth stake will rise to 150,000 Volts above ground (at best! at worst try about 2,000,000 Volts). Of course w_tom will claim that Lightning is mysteriously different and does not follow Ohms law but he will be as usual unable to explain why or prove this.
And as illustrated above single Earth stakes are inadequate (which is why exchanges use multiple stakes) and multiple earth stake earthing systems are not practical in most domestic situations so even if MOVs were 100% failproof (they are not) you still would not be able to claim (as w_tom does) that they offer 100% effective protection .......
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