All Variacs I have seen are transformer (or autotransformer) windings on a toroid core with the windings available to a brush that sweeps around. They provide nice variable voltage but no isolation.
I have designed EMP protection for missile silos. I have designed lightning protection for aircraft. I have designed surge protection for aircraft.
I have not designed surge protection for households.
But once in a start up, I was testing the upper limit of the input Voltage range for the switching powers supply I had designed for an ultrasound cart. I used a surge protector power strip as an extension chord. I dialed up up the 60Hz AC to a couple hundred VAC.
If the surge protector worked for a while, I don't know. But the stink of the smoke that came out of that surge protector had to be smelled to be believed.
You needed a protector with larger smoke packets. Yours ran out too soon!
Paul
I have a fairly expensive business phone system in my house, central control box and stations here and there. So, I made my own protector. I used a 10 Ohm 1 Watt film resistor in series with each incoming phone wire, and then connected to a 3-terminal gas tube arrestor. The idea is the film resistors blow like ultra-fast fuses during a severe surge, allowing the gas tube to handle what got through before. This has worked well, I've never had any damage to the phone system, but the DSL modems I used to use got blitzed a couple times. The resistors did get popped a couple times, too. I don't think you can get this kind of phone wire arrestor anywhere as a complete unit, except maybe from a telephone physical plant supplier. The gas tubes can be bought from Digi-Key and similar electronics distributors.
I have had some other gear damaged, but due to the nature of the equipment, I am pretty sure it was NOT from anything coming in the power lines. Wires running from one end of your house to the other can develop thousands of Volts when there is a nearby lightning strike, due to magnetic induction. I've had some stuff in my home burglar alarm damaged, as well as an ethernet port on a computer. (Most of this damage all happened in one incident, nearby lightning strike.)
So, I'm not so sure that power line protectors will actually prevent a whole lot of damage.
Jon
The standard protectors are tested against is the so-called 8/20 surge, the 8 means an 8 MICROSECOND rise time. So, the current rises to it's peak value in 8 us, then decays in 20 us after that. Relays take many milliseconds to react, and a lightning surge will just jump right over the open contacts, anyway. So, totally FORGET anything using relays.
Jon
SSR's generally use SCR's, which have the property that they don't turn off until the current is interrupted. Normal 60 Hz power turns off 120 times a second. But, when you tell the thing to turn off during a surge, it will totally ignore the command because the current is still flowing.
Really high-end UPS's do use fancy devices like back-to-back giant IGBT's, but most probably just use an electro-mechanical relay, and are designed to supplement dropped line power, not protect the load. There are "on line" UPS's that only use electromechanical relays to bypass a failed inverter, and otherwise all connection from input to output is through the DC battery bank. These are usually pretty expensive (thousands of $ for a small one) noisy and waste a lot of power, too.
Jon
I remember at work in the early '80's (before PC) getting a whole bunch of modems and a PDP/11-23+ comm board smoked due to a near miss. The modems all turned into maracas. IT said it was induced surge on the phone lines. I saw a lot of lightning arrestor stuff going up on our feeders after that. We were about 5 miles of wire away from our nearest plant power house.
After that, didn't have a problem. Coastal Texas gets a LOT of lightning.
My wife is a big fan of the "Holmes on Homes" show (which is actually pretty good). They go around fixing messes previous contractors have made of house construction/renovation jobs. They regularly install whole house surge arrestors on the breaker panels when they re-wire a place.
We've been thinking of getting one installed, so I did a little research. Leviton seems to be the biggest vendor in the US. They have an interesting dodge, which is a surge arrestor that goes in series with electric meter, inside the metter housing. In my case, this is outside of the house, which means if it turns into a fireball, it probably won't do a lot of damage. I also like the idea of stopping the surge as early in the wiring as possible.
Doug White
A friend suffered a 33,000 volt fault to the local distribution. As a result, hundreds of electric meters were blown from their pans. At least 100 clear plastic meter covers in pieces 10 meters from the pan.
Many neighbors suffered damaged electronics and protectors similar to yours. Fortunately, no fires. At least one neighbor had a destroyed 20 amp circuit breaker.
But my friend knows someone who knows this stuff. He only had a 'whole house' protector installed. Therefore he had no damage other than an exploded meter. Even the 'whole house' protector remained functional.
Just another reason why informed consumers earth one 'whole house' protector and do not made money on plug-in protectors. That Belkin does not even claim protection in its numeric specs.
BTW, electric company was not responsible for any damage (as expected). Many electric customers had their meter pans completely replaced due to the explosive power in that 33,000 volt fault.
That is not what I said. I said those are not MOVs. MOVs have excessive capacitance. Telcos use a different device that does not have that excessive capacitance. Please read what was posted. You got caught lying elsewhere. So everything from you is only an attack.
Any protection that might work adjacent to electronics is already inside electronics.
Informed consumers dissipate energy so that surges are not even inside the building.
That Belkin did what plug-in protectors do too often. Threaten human life. Any protector that fails during a surge was ineffective - grossly undersized for that surge. The Leviton and 'whole house' protectors from so many other companies much earth a direct lightning strike - and remain functional.
A direct lightning strike is typically 20,000 amps. Therefore the minimally sized 'whole house' protector is 50,000 amps. 50,000 amps without failure.
The most rare of surges is 100,000 amps. An IEEE paper demonstrates what happens when that 100,000 lightning strike hits the utility power wire. Maybe 40,000 amps attempts to enter the home. (the IEEE picture assumes the 'primary' surge protection system is also properly installed).
Only more responsible companies sell 'whole house' protectors. Not in the list are APC, Tripplite, Belkin, and Monster. Companies that sell protectors for real world protection include Leviton, Square D, General Electric, Intermatic, Keison, and Siemens. An effective Cutler-Hammer solution sells in Lowes and Home Depot for less than $50.
And again, no protector is protection - despite what others have posted. Protection is always about where energy dissipates. Always. Either the protector makes an always required short (ie 'less than 10 foot') connection to earth ground. Or that surge will hunt for earth ground destructively via appliances.
Bud has kindly provided the IEEE citation that shows same. See:
All appliances already contain any protection that will work adjacent to the appliance. Your concern is the rare surge that will overwhelm internal appliance protection (ie my friend's 33,000 volt wire dropping on local distribution). Any potentially destructive surge earthed without entering a building will not go hunting 8000 volts destructively via appliances - page 42 figure 8.
The only thing that makes a protector effective is its earth ground. Therefore any money wasted on plug-in protectors is better spent upgrading earth ground. Protection is always about where energy dissipates - which is why earthing must meet and exceed post 1990 National Electrical code. Which is why informed homeowners upgrade what dissipates energy harmlessly outside the building.
This is true of every protector. Why a 'whole house' protector is so effective and why that Belkin does not even claim effective protection in its specs. This: No earth ground means no effective protection. A protector is only as effective as its earth ground. Protection is always about where that energy dissipates =96 earth ground.
In professional papers, tiering is not about protectors. Tiering is about the only system component that dissipates the energy. Every protection layer is defined by that component ALWAYS required in each protection layer - the single point earth ground. The only item that dissipates that energy. Every protection =91tier=92 is defined only by the earth ground. Any protector without earthing does not =91tiering=92.
A residential 'whole house' protector is discussed. But that entire protection =93layer=94 is defined by what the protector connects to - earth ground. Homeowners should also inspect their 'primary' surge protection system. That is the other protection =93layer=94:
What happens if the protector does not make that short (ie 'less than
10 foot') connection to earth? That energy must dissipate somewhere? Bud=92s IEEE citation =96 page 42 Figure 8 =96 shows where tha= t energy dissipates: 8000 volts destructively via nearby appliances. Either that energy is earthed. Or that energy will hunt for earth ground inside the building destructively via appliances. Both IEEE and NIST make that point.I am being kind. I have only called them ineffective. NIST is blunter about what a protector without earthing does:
See those pictures of the Belkin posted elsewhere? It even threatened human life. And the NIST also describes plug-in protectors are >useless ... can be useless if grounding is not done properly.
Only more responsible companies sell effective protectors. With an always required, dedicated wire to make a short connection to earth. Responsible companies including General Electric, Leviton, Intermatic, Siemens, Square D, and even the Cutler-Hammer solution that sells in Lowes and Home Depot for less than $50. In every case, an effective protector has a wire to dissipate energy harmlessly into earth. Plug- in protectors do not =96 are not part of a =91tiered=92 solution. Without earthing (ie plug-in protectors), "The best surge protection in the world can be useless if grounding is not done properly." Could they be any blunter? Protection is always about where energy dissipates. Each protection layer is defined by what provides protection =96 the single point earth ground.
Secondary protection is earthing at the service entrance. Primary protection is earthing by the utility. Each protection layer is about where energy dissipates =96 not by some high profit box that somehow makes energy magically disappear.
Idiot
You don't have to be so sure. The IEEE and NIST are though.
Another factor, many of the surge protectors intended for panel use have indicator lights that show the status. Some even have audible alarms to indicate that the protection has taken a hit and is no longer functioning. If it's buried in the meter housing, you have no way of knowing if it is still functioning.
The only Belkin that failed in this thread was from crossed power lines. It was not a surge, and neither service panel or plug-in suppressors are designed to protect from the much longer duration events caused by crossed power lines.
Service panel suppressors are a real good idea. But from the NIST guide: "Q - Will a surge protector installed at the service entrance be sufficient for the whole house? A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."
Service panel suppressors do not prevent high voltages from developing between power and signal wires. To limit the voltage you need a *short* wire connecting the cable/phone entrance protectors to the ground at the power service.
(And as someone pointed out, a near lightning strike can then induce voltages with interior house wiring acting as an antenna.)
Much of the equipment damaged has power plus phone/cable connections, and is likely damaged by high voltage between power and signal wires.
Martzloff (NIST surge expert) has a paper (probably what w refers to) that has a 100,000A lightning strike to a utility pole behind a house with typical urban overhead distribution. The calculated average probability of a worse event is once in 8,000 years. There are multiple paths to earth so 'only' 40,000A is directed to the house on the service neutral. Service neutrals in the US are connected to ground at the service panel and connected to the earthing electrode(s) dissipating that energy. Some of the energy is transferred to the hot wires and the max probable surge current per wire is 10,000A (also in the IEEE guide pdf page 27).
Incidentally, at about 6,000V from hot bus to enclosure (ground) there is arc-over. After the arc is established the voltage is hundreds of volts. If there is no service panel suppressor this is what dissipates most of the energy on the hot wires. It is one of the reasons so little energy is dissipated in MOVs in plug-in suppressors.
Repeating traders response to w's repeated drivel - the "real world protection" all these manufacturers (except SquareD) sell includes plug-in suppressors. And the $50 devices do not meet w's minimum specs.
For its best service panel suppressor SquareD says "electronic equipment may need additional protection by installing plug-in [suppressors] at the point of use", and the connected equipment warranty is double when "used in conjunction with ... a point of use surge protective device."
If poor w could only read and think he could discover what the IEEE guide says in this example:
- A plug-in suppressor protects the TV connected to it.
- "To protect TV2, a second multiport protector located at TV2 is required."
- In the example a surge comes in on a cable service with the ground wire from cable entry ground block to the ground at the power service that is far too long (as in my last post). In that case the IEEE guide says "the only effective way of protecting the equipment is to use a multiport [plug-in] protector."
- w's favored power service suppressor would provide absolutely NO protection.
It is simply a lie that the plug-in suppressor in the IEEE example damages the second TV.
Lacking any source that supports his drivel w tries to twist an example in the IEEE guide that shows how plug-in suppressors provide protection.
Neither plug-in or service panel suppressors will reliably protect from crossed power lines. This is idiocy.
Provide a spec from any manufacturer that claims such protection.
Martzloff has written "the impedance of the grounding system to `true earth' is far less important than the integrity of the bonding of the various parts of the grounding system." That is - short ground wires from the telephone and cable entry protectors (and dish...) to the ground at the power service.
Complete nonsense.
w's religious mantras protects him from disturbing thoughts (aka reality). Still not explained - why aren't airplanes crashing daily when they get hit by lightning (or do they drag an earthing chain)?
Everyone is in favor of earthing. The IEEE guide explains, for anyone who can think, that plug-in suppressors do not work primarily by earthing and that earthing occurs elsewhere.
For real science read the IEEE and NIST guides - links provided . Both say plug-in suppressors are effective.
There are 98,615,938 other web sites, including 13,843,032 by lunatics, and w can't find another lunatic that says plug-in suppressors are NOT effective. All you have are w's opinions based on his religious belief in earthing.
Still never answered - simple questions:
- Why do the only 2 examples of protection in the IEEE guide use plug-in suppressors?
- Why does the NIST guide says plug-in suppressors are "the easiest solution"?
- Why does the NIST guide say "One effective solution is to have the consumer install" a multiport plug-in suppressor?
- How would a service panel suppressor provide any protection in the IEEE example, pdf page 42?
- Why does the IEEE guide say for distant service points "the only effective way of protecting the equipment is to use a multiport [plug-in] protector"?
- Why do your favorite manufacturers make plug-in suppressors?
- Why does favorite manufacturer SquareD say (for their service panel suppressor) "electronic equipment may need additional protection by installing plug-in [suppressors] at the point of use"?
I have not noticed that w is a reliable source of what happens. Perhaps you could provide a newspaper article?
MOVs are the basic protection components for virtually all power circuit surge suppressors. A MOV that can easily handle a 33,000V surge for 100 microseconds is rapidly burned out by a crossed power line ("temporary overvoltage", not a "surge"). Suggesting that a service panel suppressor will provide protection is idiocy.
Provide a spec from any manufacturer that their suppressor protects from crossed power lines.
You would, in all probability, have to have permission from the utility to use it.
The clamp voltage is 800V. According to Martzloff (was the NIST surge expert) equipment can withstand about 600-800V surges. The 800V rating sounds way too high to me. (On the other hand, the 330V rating on most suppressors may be lower than needed.) It is a "nominal" clamp voltage. With a strong surge the voltage is forced upward from 800V.
If there is a strong surge, the path to earth is through the neutral from meter can to service panel, through the required neutral-ground bond (almost always in the service panel), and to the earthing electrode. The voltage drop on the neutral will add to the clamp voltage. A surge is a very short duration event, so the current components are relatively high frequency, so the inductance of the wire is more important than the resistance. See the discussion on lead length in the IEEE guide starting pdf page 22. In effect you are adding the neutral wire to the lead length.
I would rather have a suppressor where I have total control over it (service panel).
Probability of catastrophic failure is very low. Martzloff has written "in fact, the major cause of [suppressor] failures is a temporary overvoltage, rather than an unusually large surge." A cause of "Temporary overvoltage" would be crossed power wires, as elsewhere in this thread.
Tom does not know anything about surge protection so he is trying to bluff his way through. he thinks he is appearing intelligent but most readers can see through his misinformation. It is too bad that he feels the need to rant about things he knows absolutely nothing about. Perhaps he could make a more informed opinion on the type of beer he is drinking.
From surge expert Martzloff: "Whole house protection consists of a protective device at the service entrance complemented by [plug-in surge suppressors] for sensitive appliances [electronic equipment] within the house." Kinda sounds like tiering to me.
Complete nonsense.
Because anyone with minimal intelligence can read in the IEEE guide that plug-in suppressors do not work primarily by earthing.
Only magic if your religious blinders prevent you from understanding how suppressors work.
The NIST (US government
Ho-hum. w just repeats the same distortions. Repeating: What does the NIST guide really say about plug-in suppressors? They are "the easiest solution". And "one effective solution is to have the consumer install" a multiport plug-in suppressor.
The lie repeated.
Ho hum - 3rd repetition. Repeating: Being responsible companies, all these manufacturers (except SquareD) sell includes plug-in suppressors. And the $50 devices do not meet w's minimum specs.
Martzloff says they are: "Whole house protection consists of a protective device at the service entrance complemented by [plug-in surge suppressors] for sensitive [electronic equipment] within the house."
And the required religious mantra. Still not explained - why aren't airplanes crashing daily when they get hit by lightning (or do they drag an earthing chain)?
Still no link to another lunatic that agrees that plug-in suppressors are NOT effective.
Still never answered - simple questions:
- Why do the only 2 examples of protection in the IEEE guide use plug-in suppressors?
- Why does the NIST guide says plug-in suppressors are "the easiest solution"?
- Why does the NIST guide say "One effective solution is to have the consumer install" a multiport plug-in suppressor?
- How would a service panel suppressor provide any protection in the IEEE example, pdf page 42?
- Why does the IEEE guide say for distant service points "the only effective way of protecting the equipment is to use a multiport [plug-in] protector"?
- Why do your favorite manufacturers make plug-in suppressors?
- Why does favorite manufacturer SquareD say (for their service panel suppressor) "electronic equipment may need additional protection by installing plug-in [suppressors] at the point of use"?
For real science read the IEEE and NIST guides. Both say plug-in suppressors are effective.
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