DIY surge protection...

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?

Reply to
Existential Angst
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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

Reply to
co_farmer

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.

Reply to
hrhofmann

I have a few whole-house (well, whole branch circuit) UL-rated surge arrestors. They are big (4" long by 2.25" diameter) plastic cans that attach to the main breaker box, and are wired into the branch circuits that they protect. The cans cost something like $50 each from the local electrical supply house, and are made by an outfit in Texas. I have a pair of their Model 302 arrestors.

The website doesn't work right for Safari or Firefox in MacOS, so it's probably MSIE only. But you can make it work anyway, with fiddling and indirection.

They are not just capacitors, they are industrial-size metal-oxide varistors plus capacitors.

No.

Probably ferrite EMI-supression "beads", which have no effect on computer-smoking surges. Yes, it's hot+return.

Joe Gwinn

Reply to
Joseph Gwinn

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.

Reply to
Existential Angst

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

Reply to
cavelamb

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!!!

Reply to
Existential Angst

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.

Reply to
Tony Hwang

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

Reply to
Robert Swinney

MOVs = Metal Oxide Varisters

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

Reply to
cavelamb

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

Reply to
co_farmer

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the microseconds. Relays take thousands of microseconds to operate.

Here's a traditional answer:

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repairmen used them to make hot-chassis sets safer to work on. I have one but use a UPS instead.

jsw

Reply to
Jim Wilkins

Someone needs to alert the Darwin Awards - Looks like we may have a last minute entry!

Reply to
salty

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

Reply to
Nate Nagel

Comedy GOLD!

Holy Crap!

Reply to
salty

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.

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or as an alternative:

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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.

Reply to
salty

You talkin' to ME, kid???

Reply to
cavelamb

Whoa! At last EA is showing his true intelligence exposing his level of ignorance. 'nuff said.

Reply to
Tony Hwang

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

Reply to
Robert Swinney

"chicken UPS's"

installations, both on PBX plants.

I recall the batts in

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.

Reply to
Tony Hwang

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