DIY surge protection...

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Awl --
On the main breaker box, for the whole house.
First Q: Is surge protection strictly lightning-related?
Holmes on Homes was emphasizing this, saying $500 wasn't much for the protection it affords. $500?????????????? Holy shit.....
Isn't surge protection just some capacitors?? Connected to where? Each hot to ground? Between hots? Values? I have a ton of run/start caps, 20 to 100 uF, 370 V.
If you have surge protection on the mains, do you then need those itty-bitty surge protectors fer yer pyooters?
Also, sometimes equipment will have an iron-like ring around a wire -- I think in power supplies, mebbe surge protectors. What is that ring doing? And which wires go thru it? Hot? Hot+return?
--
EA



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wrote:

Surge protectors are not capacitors. They are made from material that will conduct electricity when the voltage exceeds some particular design value. That excess electric power is converted to heat in the surge protector. If the "surge" or spike is too long lasting or occurs so often that the surge protector does not have time to cool, it will eventually produce smoke and stop working. At that time any and all surges and spikes will continue on to the rest of your house.
Usually the surge protector will die without you knowing about the death. There is no way to test them without a spike generator and an oscilloscope.
The power spikes can come from anywhere. I personally experienced equipment destroying spikes that came from the telephone wires. A construction company was excavating very deeply for a sewer pumping station near my office. Somehow they connected 220 volts to the buried telephone cable. The power went through the local phone company junction box and into our phone system and fax machine. The surge protectors immediately absorbed all the power they could and produced smoke. Then the power continued on to burn out circuit boards in the equipment.
We only discovered the source of the problem when a few days later I discovered a telephone guy installing a new junction box near our office. He told me about the construction company problem and how they were paying for the damage. They also paid us.
So, bottom line is the protectors are probably a one-time only protection. There is no easy way to test. The surge may come from an unprotected source. This applies to all protectors, including all- house protectors. All lines coming to a house must be protected, Not just the "hot" lines.
The "iron rings" you refer to are ferrite RF supressors. They reduce the electronic noise generated by switching power supplies.
Paul
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Paul sez::
""The power spikes can come from anywhere. I personally experienced equipment destroying spikes that came from the telephone wires. ASo, bottom line is the protectors are probably a one-time only protection. There is no easy way to test. The surge may come from an unprotected source. This applies to all protectors, including all- house protectors. All lines coming to a house must be protected, Not just the "hot" lines.""
Yep! Call them, "Fail dead and burned open" with usu. no visible way of determining when failure occurrs. Yeah, I know some have a pilot light but it is easy to ignore.
Bob Swinney
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That isn't correct. The main function of a surge protector is to shunt the current to ground. In doing so, SOME of the power is converted to heat as it passes through because the MOVs are not perfect conductors and do have some small resistance.

All of the good whole house surge protectors that I have seen have indicator lights that show if they are still functioning or not. Some also have audible alarms to signal that they have failed, or relay contacts that can be sent to a remote alarm system, etc.

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On Sun, 21 Mar 2010 05:20:14 -0700 (PDT), snipped-for-privacy@optonline.net wrote:

Ground schmound. The ground could be the hot wire. Or not at all involved in the surge.
--
Cliff

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wrote:

Idiot
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On Tue, 23 Mar 2010 10:23:29 -0700 (PDT), snipped-for-privacy@optonline.net wrote:

You know nothing about it, eh?
--
Cliff

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snipped-for-privacy@coinet.com wrote:

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
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wrote:

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.
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You don't have to be so sure. The IEEE and NIST are though.
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wrote:

They are not capacitors. They are electronic-semiconductor devices that are open circuit until some voltage threshold is exceeded, then they act like a very low resistance to try to limit the voltage. The limiting factor is the amount of power the devices can withstand before exploding due to the heat they generate when acting as s short circuit. I don't know a lot more than that, except that they are usually rated in Joules of energy they can dissipate before blowing up. They certainly cannot handle a direct strike to the power line, but induced voltage spikes due to nearby lightning can be handled if the joule rating is high enough.
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wrote:

They are not capacitors. They are electronic-semiconductor devices that are open circuit until some voltage threshold is exceeded, then they act like a very low resistance to try to limit the voltage. The limiting factor is the amount of power the devices can withstand before exploding due to the heat they generate when acting as s short circuit. I don't know a lot more than that, except that they are usually rated in Joules of energy they can dissipate before blowing up. They certainly cannot handle a direct strike to the power line, but induced voltage spikes due to nearby lightning can be handled if the joule rating is high enough.
=================================================== So the surge protector is a kind of crude voltage regulator?
Well, how about this:
Why not put a 100 A relay in the service, with the coil connected to a fast-acting voltage-sensing amplifier. If the voltage goes up by more than, say, 10%, the relay is activated (or deactivated, if NO), all power to the house is broken, with the relay latching out, requiring a manual re-start. Proly a NO relay.
A little more dramatic/intrusive in its action than surge protector, in that power is removed, but it should do the job, protection-wise. AND this would have the advantage of being re-usable essentially forever, and also testable.
If you wanted to get fancy, you could have this coordinated with a UPS and generator, so that no perceptible power interruption occurs. Much more $$, of course.
--
EA



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Existential Angst wrote:

Relays are mechanical devices and, as such, operate in slo-mo compared to electricity.
--

Richard Lamb
http://www.home.earthlink.net/~cavelamb /
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What do fast-acting UPS's use? Use the same thing? Mebbe solid state relays?
They're proly cheaper than mechanicals, by now, and I would assume pretty fast. There's an A/C supply outfit that sells, iirc, a 2 pole 50 A jobby for under $20. The neat thing is, the "coil" is good for, like, 100-300 V!!!
--
EA

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Existential Angst wrote:

MOVs = Metal Oxide Varisters

Spikes can go WAY bigger than a paltry 300 v And the unsuppressed arc across a relay contact - 30KV?
--

Richard Lamb
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also Transzorbs,gas discharge tubes,in-series inductors to slow down the strike's rise-time,even back-to-back zeners(not good).

WAY cheaper. Most of your commercial surge protectors use them,along with a fast blow fuse and maybe a line filter if you're lucky.
DAGS.
--
Jim Yanik
jyanik
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Jim Yanik wrote:

Can Gas discharge tubes be wired in series to increase the trigger voltage. I have a bunch of 70V ones I could use in my panel if so.
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wrote:

You were probably still a baby when the whole thing about power protection got started. There was a HUGE argument between marketing people and engineers relating to "UPS". Marketing called them uninterruptable power sources (UPS) and engineers demanded they be called Stand-By power sources(SPS). All the things you buy today are really stand-by power sources. They have a real mechanical relay that switches from the power line to battery source. A real UPS will cost many hundreds to many thousands of dollars. They continually supply power from batteries and the AC just keeps the batteries charged. An electronic circuit keeps the internally generated AC synchronized to the external power frequency. The marketing people finally won the battle. Guess it was the money, not the truth.
All computers and associated equipment, today, used switching power supplies which can continue to operate during the 2-4 cycles it takes the mechanical relay to switch and the time to start the electronics to begin supplying AC power.
Paul
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On 03/20/2010 01:53 PM, snipped-for-privacy@coinet.com wrote:

I agree with you, but you can get a "true online" UPS for less than several thousand dollars (but more than the typical thing you'll find at your local computer store)
The keywords that differentiate the two are "line-interactive" (as you describe) and "true online" (which powers the UPS receptacles from the batteries through an inverter 100% of the time.)
Now when you talk about true online UPS units, you also have to consider the quality of the power that comes out of them... need to find one with a GOOD inverter that produces a nice sine wave...
nate
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replace "roosters" with "cox" to reply.
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snipped-for-privacy@coinet.com wrote:

You talkin' to ME, kid???

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Richard Lamb
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