DIY surge protection...

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Paul sez:
"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."
One very knowledgeable cohort of mine used to speak of them as real UPS's and "chicken UPS's" During that time, I was project manager on a couple of large UPS installations, both on PBX plants. One was a 4000 line PBX and the other was 2000 line. They were Lorraine Electric units, uninterruptible in every sense of the word, with huge lead-acid batterys. As I recall the batts in the 4000 line unit were sized for nominally 24 hours.
Bob Swinney
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Robert Swinney wrote:

Hi, In my working days in radio telcomm. UPS was composed of battery bank, motor-generator set and control(switching) unit. I don't recall we ever suffered radio link outage. This is true UPS.
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No, it isn't. A "true" GPS, be it motor-gen or otherwise, is not the genuine animal unless it's output is being generated constantly whether commercial power is present or not. A motor-gen UPS would not be fit the true GPS definition unless the generator ran constantly from its source of power, battery or commercial. In the "true" GPS, switching is implemented only in the event of primary power failure; and then only to interrupt or restore primary power to the batteries charging component.
Bob Swinney
Robert Swinney wrote:

Hi, In my working days in radio telcomm. UPS was composed of battery bank, motor-generator set and control(switching) unit. I don't recall we ever suffered radio link outage. This is true UPS.
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The land-line phones usually work. 40 VDC IIRC.
--
Cliff

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Cliff wrote:

48 volts DC standard at the central office. I've seen all sorts of variations on POTS lines but the standard is 48 VDC.
TDD
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Existential Angst wrote:

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
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http://en.wikipedia.org/wiki/Varistor Note the microseconds. Relays take thousands of microseconds to operate.
Here's a traditional answer: http://www.solahd.com/products/powerconditioning/cvs.htm TV repairmen used them to make hot-chassis sets safer to work on. I have one but use a UPS instead.
jsw
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On Sat, 20 Mar 2010 10:57:42 -0700 (PDT), Jim Wilkins

What you need to make working on a hot chassis safer is an isolation transformer.
Many power conditioners use one, but electronic service technicians usually use a Variac, which is an isolation transformer that has a variable output control. Useful for "bringing up" voltage gradually for various purposes, in addition to the safety it provides.
http://variac.com /
or as an alternative:
http://www.fotronic.com/bk-precision/power-supplies/1653a.htm
The Variac is available with higher current capability than the B&K, so it is preferred by people who work on big TV's and commercial sound reinforcement.
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snipped-for-privacy@dog.com wrote:

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.
--
bud--

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wrote:

Sorry. I didn't mean to imply that all variacs were isolated output.
http://instrumentation-central.com/Staco/PDFCutSheets/VT%20isolated.pdf
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often,the "protected" parts are faster to blow than the protection device.
there are specs on how fast such protection has to operate. It's a few nanoseconds. also,how much energy)in joules) that it must be able to shunt or absorb. Often,the strike is way more than the device can tolerate.
I've seen MOVs that has absorbed a lightning strike and blew apart,yet the power supply itself survived.All it needed was a new fuse and cleaning the blown MOV's metal deposits off the PCB.
--
Jim Yanik
jyanik
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Existential Angst wrote:

Hmmm, So you think coil driven mechanical relay is as fast as spikes or surge? Forget it. But there is such a thing call S.S. relay. and it is not a voltage regulator it is a limiter.
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On Sat, 20 Mar 2010 13:25:50 -0400, "Existential Angst"

Comedy GOLD!
Holy Crap!
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Existential Angst wrote:

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
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wrote:

Either you buy a protector that will somehow absorb all that energy. Or you buy protectors based upon how it was done even 100 years ago. Protection is always about where energy dissipated. Either that energy remains outside the building. Or that energy is inside hunting for earth ground destructively via appliances. Adjacent protectors simply give surges even more potentially destructive paths through adjacent appliances.
An effective surge protector means even the protector remains functional. A minimal 'whole house' protector starts at 50,000 amps. Direct lightning strikes are typically 20,000 amps. Yes, the protector must be sized to even earth direct lightning strikes and remain functional. And that means the connection to earth must be additional requirements - short ('less than 10 feet) to earth, no sharp wire bends, no splices. all protectors meet at (again 'less than 10 feet to') the single point earth ground, ground wires separated from other non-ground wires, not inside metallic conduit, etc.
Protection is always about where energy dissipates. If those hundreds of thousands of joules dissipate in earth, then no damage. This is how it was done even 100 years ago.
But somehow a magic box next to the appliance will absorb all those joules? Always view the tech specs. Plug-in protectors rates at hundreds of joules will somehow make hundreds of thousands just disappear? That is what they claim. In analysis, we even traced surges earthed destructive through a network of powered off computers because the surge was permitted inside the building. And because a surge on the black (hot) wire was connected directly to the motherboard by the protector. The protector bypassed protection inside the computer's power supply.
Telcos do not waste money on protectors adjacent to electronics. That switching center must never suffer damage. A switching center, connected to overhead wires all over town, may suffer 100 surges with each thunderstorm - and no damage. Why? Each protector connects short to the single point earth ground. And the protector is up to 50 meters separated from electronics. That separation increases protection.
No protector is protection. None. The only effective protectors make that short connection to single point earth ground. Ineffective protectors (a $3 power strip with some ten cent protector parts selling for $25 or $150) are profit centers. The NIST (US government research agency) discusses those ineffective protectors by describing what every protector must do:

The NIST describes plug-in protectors as "useless". Obviously. It does not even claim protection in its numeric specs. Find those spec numbers that list each type of surge and protection from that surge? No plug-in protector makes protection claims. They are a profit center.
Protection is always about where energy dissipates. IOW why facilities with effective protection both meet and exceed post 1990 National Electrical code. Where does energy dissipate? A protector is only as effective as its earth ground - which no plug-in protector has and therefore will not discuss. Effective 'whole house' protectors come from General Electric, Keison, Intermatic, Siemens, Square D, and Leviton. An effective Cutler-Hammer solution sells in Lowes and Home Depot for less than $50.
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How bout a surge from downed power lines? Ours got knocked down from ice on trees falling on the main lines into the house 4am Christmas eve. Started a fire (12" flames) on the Belkin UL approved spike/ surge protector right next to the christmas tree & plasma TV! Could never get an answer as to why this happened. Knocked out a couple other surge strips including a plug in CO2 detector. Thank god thats all that happened.
http://users.cin.net/~milgil/Belkin_burned1.JPG
http://users.cin.net/~milgil/Belkin_burned2.JPG
http://users.cin.net/~milgil/Belkin_burned3.JPG
http://users.cin.net/~milgil/Belkin_burned4.JPG
http://users.cin.net/~milgil/Belkin_burned5.JPG
Must be something to do with the end of the power- where it dissipates ?
--
BB;s #9
The older you get
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cncmillgil wrote:

Looks like a pretty good case for metal enclosed surge protectors.
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While I was staying in a motel in Southington, CT an empty room burned. Smoke detector started the fire. Melted & dripped flaming plastic on the bed ....
(Had central wiring back to the office & was poorly installed.)
--
Cliff

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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.
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westom wrote:

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.
--
bud--

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