w_tom wrote in news: snipped-for-privacy@hotmail.com:
MOVs are supposed to be used with a FUSE,so that when the MOV conducts to shunt the spike,the fuse blows.Sometimes MOVs degrade with minor spikes,then totally short,sometimes they blow apart completely.I've serviced commercial test equipment that had MOVs split open,with the fuse blown,yet the circuitry was unharmed,only needing a new MOV and fuse to restore operation.Others had the MOV blown completely apart.(and fuse open.)
And I live in central Florida,the lightning capital of the US.
Of course a manufacturer of _series_ mode suppressors (Zero Surge) is going to go out of their way to show how shunt mode suppressors are supposedly ineffective.......how do you know that the damaged suppressors shown on that web page were properly grounded in the first place? _Any_ improperly grounded or installed surge protector will get a hole blown in it during a big hit. Even a properly connected surge protector can be suffer big time damage......which is why the better manufacturers, such as Tripplite, use metal cases for their protectors.
Talk about misleading someone.......the LED lights when the MOV is no longer effective, telling one that it's time to replace it.
Some, yes. Others, no.
Tripplite does.
Why then did my mothers $2000 Sony TV _not_ get damaged in a recent _direct_lightning strike (fire ball and all), while other (unprotected) TV's and phones _did_ get damaged? You gonna tell me that the TV protected itself?
Try again. Any manufacturer of quality surge protectors will tell you that you _must_ connect it to a properly grounded system, and, in fact, they tell you that your warranty will be jeopardized if you don't.......and they usually reserve the right to inspect your premises to see if it was.
Horse droppings. Faster response time does make a difference. How does this apply to your recommendation for "whole house protectors"? There's a response time for those too.......which is all the more reason to install a point-of-use protector to pick up anything that gets by the whole house protector. If you look at _any_ surge protection program offered by power companies you will see that this is exactly what they do.......whole house protector PLUS point-of-use protector. I guess they are "uninformed" also?
No, that's why we install surge protection.
I wouldn't be so sure about that Tom.......I've personally seen holes blown in 911 system surge protectors. Surge protection for those types of buildings starts with proper power wiring.
That's funny, it just saved a $2000 Sony TV. Just not having to lift that
200 pound monster (for replacement) was thanks enough.
In BIG letters in the instructions that come with the suppressor.
Funny how that telco "protector" got fried too........_and_ didn't do a damn thing to save the phones that were not connected to the Tripplite.
Probably because you've never owned a Tripplite, and thus, never read the instructions.
They DO.
I've personally seen a Tripplite protect an expensive TV from a direct lightning strike......or are you going to tell me that the TV protected itself while all the other (unprotected) TV's and phones got blown out?
How _do_ you reach all of your conclusions? Are you a _power_ electrical engineer, or do you just read web pages and try to piece this info together as you go?
That is not in dispute. There very well could be a fire hazard associated with surgistors but this is irrelevant as to whether they actually provide any protection to electronic circuitry from voltage spikes on the mains.
No .. jums Ara Movsesien you sycho AKA James keene Ben frome Amos Ajays home repair MY toys in 91 were 30000 + thats THIRTY THOUS for you ARA MOVSESIAN Total Elec 40000.........
We cannot say why your mother's Sony TV was not damaged. Remember, when discussing surges, then wire becomes another electronic component. Wire has impedance when discussing surges. Possible that your mother's TV would not be damage also if not connected to a surge protector. Was it in a circuit between incoming surge to earth ground? Maybe those other destroyed appliances acted more like a 'whole house' protector - shunting the surge to earth ground to protect your mother's TV. Furthermore the Sony could have superior internal protection. What are its common mode and differential mode transient limits? Without electronic details (remembering that wire is another electronic component in a surge protection system), we cannot say why one item is damaged and another is not.
TV and VCR side by side. Both plugged into same power outlet. VCR was damaged. TV was not. Both confronted by the same AC mains surge. But TV did not make a good outgoing connection to earth ground. VCR did. First we need the complete schematic, including wires inside walls and other conductive materials such as baseboard heat and concrete floors, to see why one appliance is or is not damaged.
Bottom line is that your mother had damage because the surge was not earthed at service entrance to a single point earth ground. A design so well proven that your telephone exchange keeps running without damage through all thunderstorms - even when connected directly to overhead wires all over town. 911 Operators don't remove their headsets and stop taking emergency calls. FM and TV electronics atop the Empire State Building and WTC suffered 25 and 40 direct strikes annually without damage - because they too use principles of 'whole house' protection even back in the 1930s. Your mother suffered damage, unnecessarily, because the surge was permitted inside her building. We call that human failure because effective protection from direct strikes is that well understood and that well proven. A surge protector is only as effective as its earth ground.
Special note to all lurkers. volts500 wrote a good explanati> ...
TrippLite ,, ISOBAR--- has - O -. NANOSECOND response............................... Old cheap stuff is 6 to 15... new is 1 ....5. Tripp is best ,, lifetime warranty on product...... LEDS Show bad unit, or wire prob........
An inline fuse is installed so that if one, single surge exceeds limits of MOVs - if MOVs are grossly undersized for the task, then surge protector will not burn down the house. Fuse is how MOV protectors meet UL1449 2nd Edition requirements - for human safety. Fuse is not for a surge protector circuit; not for transistor safety.
Data sheets from MOV manufacturers are clear about this with graphs. MOVs do not fail short circuited - except when they are undersized for one surge. Size is measured in joules - another critical number. MOVs degrade as demonstrated by datasheet graphs for size of surges (in current and time) verses number of surges. MOVs don't explode if properly sized such as in good 'whole house' protectors. MOVs simply degrade. But if too much energy is applied in one surge (just like a wire) then the MOV fails catastrophically - because human did not install a protector of sufficient joules.
Just because one saw a failed, undersized MOV does not mean that failure is the normal. Experience without knowledge from those datasheets means no valid conclusions can be drawn. Observation combined with those datasheets says that 'MOV with hole' was grossly undersized. The normal failure mode for an MOV is increased threshold or let-through voltage. Industry standard. MOV is completely degraded when the MOV voltage increases by 10%. How does one dispute what manufacturer data sheets say? More likely those data sheets were not read.
MOV was grossly undersized if it short circuits or explodes
- which is why an inline fuse is installed for human safety and UL1449 requirements.
An MOV that degrades 10% is not reported as defective by the LED. But an MOV protector that fails because grossly undersized can be reported by the LED. LED cannot report a good protector. LED can only report a surge protector failed because it was grossly undersized - and therefore blew the thermal protection device (fuse).
Pictures properly identify what that LED indicates:
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makes series mode protectors; not shunt mode. But their pictures are consistent with MOV datasheets. That LED cannot report a good surge protector. It can only report a surge protector failed because it was grossly undersized. Where one lives does not mean one first read those manufacturer data sheets. Speculation without first learning the principles and reading data sheets is a typical human mistake.
If the MOV short circuits, then it was grossly undersized for the task.
Lets take the specification from a Seasonic power supply: Dielectric withstand, input to frame/ground: 1800VAC,
1sec. Dielectric withstand, input to output: 1800VAC, 1sec. Is that not internal protection? It is routine for any 120 VAC appliance to withstandat least 600 volts for 120 microseconds without damage - a minimal requirement. Again, it is internal protection. That is the job of 'whole house' protectors - to shunt surges to earth before they enter the building - so that the 1800 volt and 600 volt internal protection inside an appliance is not exceeded.
Yes, electr>> Appliances already have internal protection that assumes
w_tom wrote in news: snipped-for-privacy@hotmail.com:
An MOV conducts when a spike is encountered;that effectively is a SHORT across your mains supply.That's how a MOV gets rid of the spike. If the 'short' duration is low,the circuit breaker or fuse may not be fast enough to respond,and there's little harm to the mains,little fire hazard.But the inline fuse aids in protection of the instrument protected,as it breaks the circuit,stopping the flow of anymore energy.
Also,the energy of spikes vary greatly,so one cannot simply select the biggest MOV for every application.
w_tom wrote in news: snipped-for-privacy@hotmail.com:
Except that there are several ways for a lightning strike or surge to enter the home and it's electronics,not solely thru the mains."Whole-house" surge protection may not address that at all.
I don't believe so Tom. As you know, lightning is a strange critter. As far as I could tell there was arcing between the aluminum siding and a splitter that a cable guy had installed on the outside of the house (unknown to us and remote from the main cable service.) The splitter was close to the siding. There was a definite flash over between the siding and the splitter, as evidenced by burn marks on the siding and charring of the splitter and cable wires, which probably accounts for the fire ball also. The Tripplite and the Sony TV were closest to that entry point, probably about 5 feet. One other small TV (unprotected) was also within 5 feet of the entry point and was fried. Two other small TV's (unprotected) were on the other side of the house and did not survive. The surge must have also came in on the phone line because the telco protector was fried and the whole box had to be replaced along with some phones. I still think that the Tripplite did it's job.
Again, TV's that were much further from the entry point were damaged.
OK, I'll conceed that.
No, that's not the case. The power ground, telco ground, and cable ground are (and were at the time of the strike) in fact connected to the same grounding electrode at the front (side) of the house.........again the entry point was in the rear (same side) of the house where the splitter had been installed, just hanging in the breeze, close to the aluminum siding. I strongly believe that had the splitter been installed on a non metallic surface and a ground rod installed at that point and connected to the ground block (and bonded to the main electric grounding system), which is what I have since done, that the surge would not have entered the house via the cable TV line(s). The aluminum siding has also since been grounded.
IMO, thanks to the cable guy who installed the splitter (flapping in the breeze next to aluminum siding) in a hidden place and didn't bother to ground it.
Where did I say that? I am NOT suggesting that I go buy some overpriced junk.
Joules rating by itself means nothing. The good ones clamp 5 to 10 times faster in nanoseconds. Overall quality, durability, size of components, metal cabinet.
So ahould I go buy $9.95 protector that has some insanely large joules rating in a yellow banner on the package? orange box had them.
For example: APC claims common mode on their UPS's. They only use a MOV as a secondary means of protection. They do warrent against lighning, and they can do that because MOVs just blow out and burn, usually worthless. I am not inclined to believe APC, triplite, zerosurge are overpriced junk. Then the $9.95 900 joule protector is pure on-the-package marketing hype, a small sized, plastic, components closely packed together piece of junk.
I have found during severe lightning storms the best protection is to totally disconnect all wiring and cabling from your electronic gear. For computers this means LAN cables, AC power, Telco, USB, mouse, keyboard, etc.
Surge suppressors are useful to dampen quick changes in circuit load from motor starts or utility switching. I wouldn't depend on any surge suppression system to control lightning effects. Many manufacturers advise you not to daisy chain multiple suppression devices. Some units by design can have an impact on your LAN cabling and throughput due to backfeeds to ground.
My not so perfect solution is a SmartPro 2200 VA Tripplite UPS feeding all my computers, PBX, and radio gear. It has surge suppression and line conditioning electronics.
My father in law once had a whole house suppressor installed at the meter pan by the electric company. They pulled it out last year when the power company said they were no longer supporting the suppressor.
A surge circuit must be better defined to understand what could and could not be damaged. To make things more complex - a transient down a wire will actually result in highest voltage at the wire's farthest end. A basic concept taught in electromagnetic wave theory. Not that it definitely applies to your mon's situation. However, the component first to suffer the highest voltage is at the far end of a long wire. Tracing surges can be that complex.
Just because the telco protector was fried does not mean a surge entered on phone line. Noted previously is how modems, fax machines, and portable phone base stations are destroyed. Incoming on AC electric. Outgoing on telephone wire. That earth ground path on phone wire is through that telco provided 'whole house' protector. Surge that damaged telco protector could have been incoming on AC electric, through household phone appliances, and outgoing through that telco protector.
It gets more interesting. If telco protector and AC electric were grounded on different sides of building, then, well first we must describe the circuit. Lightning seeks earth ground that is 5 miles diagonal from cloud to earth. Shortest electrical path is 3 miles cloud to earth, then 4 miles through earth to those other charges. If home is in that 4 mile path, then surge enters on (say) phone line ground, passes destructively through household appliances, then returns to earth on AC electric ground. Just another reason why basic concepts such as single point earth ground is so important.
Either way, the Tripplet protector did nothing to provide protection.
In your mother's case, the "flapping in the breeze" cable splitter could have been a connection, through siding, into household AC wire behind siding, then through various appliances to earth ground. Aluminum siding, concrete floors, copper and cast iron pipes in contact with those other items, hot water heat pipes, linoleum tile, etc all mean that once a surge has entered the building, then destructive surge circuits appear everywhere. Again, this is why all incoming utilities must first be earthed at single point earth ground. This is also why halo ground or, even bettter, Ufer grounds can be so important to better surge protection (attention to anyone about to build their own house).
In another example, vitims were on vacation when lightning struck AC mains. Surge entered two powered off computers via plug-in protectors. They, in turn carried the surge through an RS-485 based network to a third computer. Surge passed out of third computer via modem. Damage was quite clear because I replaced every defective electronic component in that circuit
- on network cards and modem - and to restore the network. What was incoming and outgoing on network cards even resulted in different damage to same type chip. This is a classic case where a plug-in protector contributed to surge damage - incoming on AC electric and outgoing on phone line. Surge protectors being too far from earth ground via AC electric safety ground.
Lightning is not capricious. Every surge damage can be traced. Once understood, it become an "Oh yeah. I didn't think of that one" experience. Protection is always about single point earth grounding - the most critical component in any surge protection 'system'. Surge protector is only as effective as its earth ground.
AC electric is almost never installed with the necessary 'whole house' protector. Even more embarrassing are how cable TV and satellite dish operators install their surge protection. They don't even need a surge protector! They only need route the wire appropriately. All homes since 1970s have required transistor protection. And yet many cable installer don't even earth to meet NEC human safety requirements! Maybe we need more immigrants so that the wiring will be done with intelligence? It certainly is not difficult to understand the single point earth ground concept except, mabye, if one is a cable TV installer.
As I posted previously, > > We cannot say why your mother's Sony TV was not damaged.
The point of "adjacent VCR and TV" - one damaged and other not - was that lightning damages for a specific reason. In this example, one was not damaged because it did not have the prerequisite incoming and outgoing surge path. Surge could have been incoming on AC electric and outgoing on cable - because cable was properly earthed before it entered the building. Or surge could have been incoming on cable and outgoing on AC electric - because cable was not earthed at service entrance.
The point is that lightning is not capricious. It damages for a specific reason. Additional point: damage on the cable side of VCR does not mean that incoming surge was from cable. Same damage could have been from AC electric surge that was outgoing on cable.
Same reasoning is why many incorrectly assume surge entered on phone line to damage modem. They assume that modem was damaged from surge on phone line because modem was damaged and computer was not. However and again, the surge had to first form a complete electrical circuit. Incoming on phone line and outgoing through computer. Or incoming on AC electric, through computer, and outgoing on phone line. Either way produces damage in the modem's DAA circuit. Surge passed through computer without damaging computer. Surge confronted every IC in that computer. But since those other ICs did not have an outgoing path, then those other computer ICs were not damaged.
To be damaged, the electronic component must first be part of a complete incoming and outgoing surge circuit.
Phone lines routinely have telco "provided for free" 'whole house' protector which is but one reason why surges incoming on phone lines are rare. Most modems have a direct connection to one AC wire which is often the incoming surge path. Adjacent surge protector can make damage more probable. Again, same point. Lightning was not capricious. Damage occurs for a specific reason. First a complete circuit - an incoming and outgoing path - must exist for surge damage to follow.
Those circulating ground currents at that TEK location are why we wire buildings beyond what NEC requires - to also eliminate ground loops. Montandon and Rubinstein demonstrate the problem (and solution) in an IEEE paper entitled "Some Observations on the Protection of Buildings Against the Induced Effects of Lightning" on 4 Nov 1998. But one need not read the paper to learn of the solution. Again, we must wire beyond what the NEC requires - as that TEK location probably demonstrated.
That NEC earth ground must be wired so all incoming utilities meet at a single point earth ground. All incoming utilities are earthed so their ground wires meet only at the common earthing point. All grounding wires routed separate from non-grounding wires (which is why plug-in or point of use protectors do not provide earth grounds). All interconnected equipment groups wired using common paths and grounded using separate, dedicated, single point grounding system.
Surge protectors are not surge protection. Surge protection is the earthing system. Surge protectors are peripherals of that surge protection 'system'. Surge protectors are but simple science. The *art* of surge protection is how that earthing is installed using concepts such as single point ground, short distances to ground, dedicated ground wires not bundled with other wires and not inside metallic conduits, careful wire routes, and, if necessary, enhancing the single point ground with halo grounds, ground plates, additional rods, or the so highly regarded Ufer ground. Even that ground wire installed by the power utility to it's pole transformer is the building's primary surge protection. 'Whole house' system is but secondary protection.
Returning to the point of original poster. Most retail surge protector are a waste of money. They don't claim effective protection as bluntly indicated by avoiding an earthing discussion. They would confuse safety ground with earth ground. They would have you believe a surge protector is surge protection. Surge protection is earth ground. The only effective surge protector connects an incoming surge short, direct, and independently (all adjectives have specific technical meaning) to that central earth ground. Plug-in surge protector manufacturers must avoid this discussion to sell product.
But a real world surge protector manufacturer discusses earthing extensively in legendary application notes because surge protection is about earthing; not about surge protectors:
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A surge protector is only as effective as its earth ground - as demonstrated by the concepts of electricity - the incoming and outgoing surge path.
My Sony TV and Sony VCR both survived a direct lightning strike to the buildings wiring, but two other tv's, a VCR, a computer, a fax, all telephones, and an answering machine were fried. The surge blew an outlet out of the wall, tripped a bunch of breakers, and blew the transformer on the pole. The lightning struck the building, not the transformer, there were witnesses to that. It was a very large surge. My point is, I believe that Sony TV's do have some sort of surge protection built into them, based only on what I saw in that strike.
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