Re: belkin power conditioner for my Samsung LCD - is it worth it???

phil-news-nospam@xxxxxxxx wrote:
On Mon, 06 Aug 2007 10:38:20 -0500 bud-- <remove.BudNews@xxxxxxx> wrote:

| You can certainly design a TV power supply to operate over a range of | 100-240V - or wider. That does not mean significant numbers of TVs are | designed for that range. The specs for the HDTV I recently bought say | "120 Volts".

I've seen both. But I'm not particularly looking for that spec since I
can satisfy my preference for balanced power at the 120 volt level using
a transformer. The only advantage of 240 volts is balance power comes
without such a transformer being needed (in a USA system ... not so for
most parts of the world where 220-240 volts is the norm).

The point of my original post was that w_’s claim that a “TV must work just fine” when the voltage is low enough for a bulb to be at 40% brightness (under 95 volts) is baloney. A few may work, but it is going to be a low percentage.. IMHO switching off is not ‘working’. (40% brightness = 95V comes from a Westinghouse lighting handbook.)




|> | A repeat of w_?s nonsense that plug-in suppressors don?t work. The IEEE |> | guide on surges and surge suppression at :
|> | http://omegaps.com/Lightning%20Guide_FINALpublishedversion_May051.pdf
|> | explains plug-in suppressors work primarily by clamping the voltage on |> | all wires (power and signal) to the common ground at the suppressor, not |> | earthing. The guide explains earthing occurs elsewhere (starting pdf |> | page 40).
|> | |> | And the IEEE guide (as well as a NIST guide) says plug-in suppressors |> | are effective. But they must be used properly.
| |> |> They must not be expected to solve issues they were not intended to
|> solve, such as dumping a lightning strike to ground.
|> | | You would probably find the IEEE guide is interesting reading.

It is.

But it is also interesting in the assumptions it makes, such as an
antenna system being for satellite purposes. Most of the rules for
that do work for terrestrial antenna systems.

If you mean a dish for a transmitter on earth vs. a dish for a satellite, I don’t see any difference between them. Almost all of the discussion, including the CATV example below, is for wired ‘Comcast’ type CATV systems. Dish is one of the signal sources for the TV protection example at the end of the guide, along with CATV and phone. Dish systems appear to often not be connected as a “single point ground” or even grounded/earthed correctly.



| The IEEE guide has an illustration, starting pdf page 40, of a surge | coming in on a CATV cable. The 'ground' wire connecting the CATV entry | block to the power service ground is 30 feet - far too long (not a | "single point ground"). As a consequence, the CATV wiring is at 10,000V | with respect to the power wiring.
| | The illustration shows a plug-in suppressor used to protect a TV. The | CATV wire must go through the suppressor. The CATV shield is connected | to the power ground at the suppressor. In addition the hot and neutral | are clamped to the common ground. And the CATV center conductor is | clamped to the common ground. As a result, the voltages on the wiring to | the TV are safe and the TV is protected.

In most cases.

Everything I have read is that plug–in suppressors with high ratings have a high probability of protecting equipment that is properly connected to it. Even better with a service panel suppressor and single point ground.

Exception such as?



| The illustration explains that the earthing of the surge still occurs | primarily through the 'ground' wire from the CATV entry block to the | power service, as the NEC intended. Not much of the surge is earthed | through the plug-in suppressor. But the suppressor protects the TV | connected to it.
| | In this case, a service panel surge protector will not help. The guide | says in this case "the only effective way of protecting the equipment is | to use a multiport protector" (although you could run a CATV wire from | the entry protector to the area of the power service, install a 2nd | ground block, and distribute wiring from there). A lot of houses have | the CATV (or phone, ...) service entry points distant from the power | service, making a "single point ground" impossible. Or the entry points | may be adjacent but not connected with short wires.

That is, unfortunately, the case for so many installations.


| The NIST has a guide on surges and surge protection at:
| http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
| According to NIST guide, US insurance information indicates equipment | most frequently damaged by lightning is
| computers with a modem connection
| TVs, VCRs and similar equipment (presumably with cable TV | connections).
| All can be damaged by high voltages between power and signal wires.

Also lacking in any reference to terrestrial TV outdoor antennas.
But that's not a problem for me.


| The NIST guide also includes:
| "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, | No for two-link appliances [equipment connected to power AND phone or | CATV 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."
| You can get direct induction from a lightning strike into the loop | formed by the power and signal wiring to a piece of equipment. But a | bigger hazard is lack of a short connection from the phone, CATV, ... | entry protectors to the earthing wire at the power service ("single | point ground").

Use of fiber optics and wireless are ways to convert two link devices
back to one link devices.

I agree that is a good way to eliminate the 2nd ‘link’. I am not aware of an optical or wireless link that is practical for the TV signal to a HDTV. And given the value of a HDTV, IMHO they are worth protecting with a plug-in suppressor. I am using one.

With wireless and optical you still will have some equipment that is 2-link, like a cable modem and wireless router. But the value of the equipment is relatively low.



| Surges on the power wiring are also clamped to the common ground at a | plug-in suppressor. Doesn't matter if they are common or transverse | mode. There are MOVs from H-G, N-G, H-N. Common mode surges entering at | the power service are converted to transverse mode by the neutral-ground | bond at the power service. If surge voltage exceeds approximately 6000V | at panels or receptacles there will be arc-over, which dumps much of the | surge energy to earth. A service panel surge suppressor would be preferable.
| | | | The IEEE guide has 2 examples of surge suppression starting pdf page 54. | Both examples use a plug-in suppressor.
| | One example is for a TV and associated equipment with CATV, phone and | satellite dish connections. It is critical that all 3 of these signal | sources pass through the plug-in suppressor.
| | The other example has a computer system with cable modem. The cable | connection must also pass through the plug-in suppressor. The example | has a UPS connected to the plug-in suppressor.
| | | | Plug-in suppressors, properly connected, will protect from surges | produced by lightning. With high ratings they can protect from rather | near strikes. The energy dissipated by the suppressor is a lot less than | that dissipated by a service panel suppressor because of the high | impedance of the branch circuit wiring. That is why some plug-in | suppressors (like the OP's Belkin PF30) can have large protected | equipment warranties.

But even these cannot fully protect from a direct strike, where the full
lightning current is coming in on whatever path(s) it found. These are
rare events, but they do happen.

If lightning hits the house directly, you have lost all control of where it goes (short of lightning rods). As you said, that is very rare.


If it comes in on power or signal wiring. survivability is better than may be expected.
---------------
François Martzloff was the NIST guru on surges until he recently retired. He wrote the NIST guide as well as may technical papers including:
http://www.eeel.nist.gov/817/pubs/spd-anthology/files/Neutral%20earth...
"The Effect of Neutral Earthing Practices on Lightning Current Dispersion in a Low-Voltage Installation"

One of the test scenarios was a US system with 3 buildings connected by separate service drops to a single transformer. All 3 houses had service panel surge suppressors. One of the houses was hit with a 100,000A surge with rise time of 10 microseconds and duration of 350 microseconds. This is a large hit with a very long duration. The hit was to the neutral service connection at the house. In total this is close to a worst possible case.

*1* The result was
21,000A was conducted to earth at the building (this lifts the ground potential at the house)
33,000A flowed away from the building on the service neutral to the transformer and other 2 buildings
23,000A went through each of the hot-neutral protectors and flowed away from the building on each hot service conductor to the transformer and other buildings.

2 of the 3 service panel surge protection devices had a peak current of 23,000A

The dissipation at the building surge protector was 3500J

*2* If the same surge hit one of the other buildings the dissipation at the surge protectors at this building was 840J.

*3* If the surge was shorter - 20 microseconds - which is probably more realistic, the surge suppressor dissipation would be 200J, or if the hit was to one of the other building the surge protector dissipation at this building would be 80J

For comparison, the *plug-in* surge protector I recently bought had rating between each pair of wires of 30,000A and 590J (1180J for both hots to ground). But my plug-in protector was rated at a higher current than occurred in any case, and the energy rating was higher than occurred except the strong hit the building (*1*). Service panel protectors would likely be rated higher. And this is near worst case.

A service panel suppressor can survive a very near hit. A plug-in suppressor could provide additional protection, particularly for high value ‘2-link’ devices.


-----------------------------------------------------------
Another Martzloff paper looks at a MOV (simulating a plug-in suppressor) at the end of a 10-50 meter branch circuit. The surge is 2,000-10,000A, and I believe 25 microseconds. There is no (service panel) suppressor at the source but there is an arc-gap at the source end with a breakdown voltage of 6,000V, which duplicates arc-over at the service panel.. Arc-over dumps a large percentage of the surge to earth. Branch circuit impedance greatly limits the surge current to the MOV at the end of the branch circuit.

In all cases the energy dissipated at the MOV was less than 1J except for a 10M branch circuit and, ironically, the lower current surges below 5,000A. Contrary to intuition, at all branch circuit lengths the energy dissipation at the MOV was lower as the surge current went up. That was because the MOV acted to clamp the voltage at the source spark gap. With the short branch circuit and lowest surge currents, the MOV prevented the gap from arcing over at all. Higher current surges forced the voltage at the gap up faster causing it to break down faster and dump more of the energy to earth.

I don't remember the branch circuit current was indicated, but it would be far below the max surge current of 10,000A. The max energy dissipation at the MOV was 22J. Plug-in suppressors are readily available with ratings higher.

----------------------------
As you probably know, service panel and plug-in suppressors do not protect by absorbing energy, but they absorb energy in the process of protecting.

MOVs have a maximum energy they can dissipate. This is the rating for a single hit. With high energy ratings, the energy of a single hit becomes a smaller percentage of the MOV single event rating. The smaller the percentage is, the larger the total cumulative energy the MOV can absorb. With small hits relative to the rated energy a suppressor cumulative energy rating may be 10 or 50 times the single event. ‘Oversized’ suppressors may never fail.

In addition, as described at length in the IEEE guide, the protected load may (or may not) be connected across the MOVs. If connected across the MOVs (preferred), the protected load will be disconnected with the MOVs if they fail.


---------------------------
In another guide Martzloff said "In fact, the major cause of TVSS [surge suppressor] failures is a temporary overvoltage, rather than an unusually large surge."


--
bud--



.

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