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Author Topic: 120VAC surge supression?  (Read 3027 times)
K7IHC
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Posts: 269




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« on: November 04, 2004, 11:35:09 AM »

Well, it happened to me yesterday.  In a post from earlier this year (http://www.eham.net/forums/StationBuilding/1114), I had expressed an interest in installing a whole-house AC power supression/surge protection unit.

Yesterday, we had a surprise hail/thunderstorm roll through here (just N. of San Francisco, CA).  I had been talking on my H/T, when a thunderclap acros town coincided with a flicker of the house lights.  I went out to the shack (garage) to disconnect and shut down my radios and found them all off.  A quick check revealed about a 4 volt output on my Astron RS-35M power supply.  After the storm passed, a check of the 8 amp fuse found an intact fuse.  However, one of the power transistors on the rear heat sink had a nice burn hole through it.  Hopefully, a replacement of this transistor will get the Astron up and running again.  None of the other internal components appeared  to be damaged. The Astron was even plugged into one of those $12 cheapie power strips (w/ alleged surge protection).

So: I'm looking for recommendations/references on a whole-house supressor unit.  Any input is welcome.
I'm lucky none of my four radios on at the time were damaged.
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W4TME
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Posts: 299




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« Reply #1 on: November 04, 2004, 02:26:32 PM »

CHeck out these products.

Look at the ICE 330 or 334

http://www.arraysolutions.com/Products/ice/impulse2.html#1

Polyphaser make one too.

http://www.polyphaser.com/kommerce_productdetail.asp?item=IL240-BP-200A

-Tim
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AA4PB
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« Reply #2 on: November 04, 2004, 03:01:57 PM »

Here on the East coast the power company is offering a whole house surge protector that they install on the meter base. It comes with a replacement/repair policy for any equipment damaged by a surge. I think the cost is $5 per month on your electric bill.
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AA4PB
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« Reply #3 on: November 04, 2004, 03:06:23 PM »

Those plug in surge protectors are pretty worthless for anything but a minor power surge. What they do is divert the surge current into the safety ground wire on your outlet. That is generally a long run of #12 or #14 conductor back to the entrance panel. It has too much resistance to keep the ground potential at the surge protector from rising under heavy current flow in the grounding conductor.
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KE4DRN
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« Reply #4 on: November 11, 2004, 04:19:18 PM »

Hi Erik,

The astron should have a MOV located at the terminal strip where the power cord enters the supply.

I would replace it with a new one, even better, some use three new mov, hot to neutral, hot to ground and neutral to ground.

Mouser has them for about 60 cents a piece.

73 james
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K4IA
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« Reply #5 on: November 12, 2004, 06:50:51 PM »

My local utility told me the whole house supressor is a heavy duty device intended to protect big equipment like air conditioner compressors.  They said it would do nothing for more sensitive equipment like electronics.

Anyone know anything more?
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K7IHC
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« Reply #6 on: November 13, 2004, 01:20:31 AM »

Hello all:
I repaired the Astron; the LM723 IC, the main chip on the supply's board, was damaged.  All of the pass transistors tested ok, even the suspect looking one.

Anyways, from a bit of looking on the Panamax website, a whole-house suppressor is really just a few MOVs and a fancy LED monitor panel.  It can only protect basic home electrical devices, not electronics.  It is still recommended that high-quality MOV/IC-based surge suppressors be used at the sites of sensitive electronic devices.

I also found that even though a high-quality suppressor is good, since the device shunts the surge back though the grounding wire, it may not be able to protect very sensitive devices.  This is due to the fact that most residential grounding circuits can be considered high-impedance circuits, given that they use long legs of 12 or 14 AWG wire. This limits their ability to carry voltage and/or current spikes of certain configurations away from the suppressor.
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AA4PB
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« Reply #7 on: November 13, 2004, 09:15:35 AM »

There is a company called Surgex that makes series mode surge supressors often used to protect A/V installations. Supposedly they work by opening the circuit during a surge rather than trying to shunt it to the grounding conductor. They are not cheap by any means.

Electrical supply houses also have panel mounted surge protectors that you can bolt to the breaker panel and protect an individual circuit. Even though they are parallel mode devices, at least they have a pretty low impedance to ground because they are located right at the panel.

The problem with locating a parallel mode protector at the equipment is that it shunts the surge to the grounding conductor. The grounding conductor is generally a long run of #12 or #14 wire so the impedance of the conductor allows the ground potential at the equipment to rise when heavy shunt currents flow in it. That can cause currents to flow in other parallel paths to ground such as coax shields, other equipment, etc.
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K7IHC
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« Reply #8 on: November 14, 2004, 12:37:10 AM »

Bob:
Thanks for the tip on the panel-mounted surge suppressors.  I may look into that, as I could easily protect a few devices on one circuit.
I'll also try to take a look at the Surgex devices and see what their cost is (probably too much for me). Opening the circuit until the *spike* has subsided sounds like the best method of protection.
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OCEANARADIO
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« Reply #9 on: November 16, 2004, 12:44:47 PM »

I see a lot of good cautionary comments about standard MOV-type surge protector power strips. Other than entrance-guarding the AC mains in a utility-approved connection at the electric meter, there is no place for MOV's in interior electronics. The only line-to-ground surge issues a home (or radio station inside one) can have, is the problem caused by the MOV power strip itself. In the U.S.A., all AC mains panels require bonding neutral to ground at the main panel. All common-mode surges riding on the power lines stop dead right there. Thereafter, surge voltages should be returned to neutral only. There is no MOV power strip made to my knowledge that does this. However both Transtector and ZeroSurge make entrance, branch and equipment source suppressors (including power strips) that are L-N only. These operate using the non-degrading silicon avalanching diodes which last for tens of thousands of surges, or about 10 years. This is the fastest response time application and incidentally, the only kind able to react fast enough to affect EMP on wiring from nearby strikes. The cutoffs are typically about 300v but your equipment can withstand that easily. Mine has, taking a half dozen nearby strikes within 100'and two of those within 50' of the power pole and dipole antennas. Some thanks of course goes to the I.C.E. multi-attack coax arrestors, but the majority of the issue from nearby strikes is SURGE and Ground Potential Rise. I was faced with either installing an oversized neutral return from my station, or installing a new separate feed (with very heavy #6 cable) for a station branch panel. I chose the latter, and have Fortress protectors on both the AC entrance and the station branch panels. These are both L-N only suppressors. Then, all equipment is plugged into L-N only power strips. Proper bonding and station grounding combined with good surge supression mark the end of worry about disconnecting equipment. It makes sense to protect the whole home, not just your station equipment.

Below is my website which describes the methodology and equipment used:

http://members.cox.net/pc-usa/station/grounding.htm

73,
Jack
Virginia Beach VA
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KT8K
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Posts: 1490




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« Reply #10 on: November 23, 2004, 09:47:37 AM »

With the 60 cent MOVs you get what you pay for.  Someone on the Elmer's forum some time back mentioned that not only are they good for about one shot, but they can burst into flames as well!  Just what I want on the carpet under my radio table!
The "Fortress" model, on the other hand, is something I'm considering (as I find and replace the MOV strips around the house).
Have a safe one ... 73 de kt8k - Tim
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AA4PB
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« Reply #11 on: November 23, 2004, 11:17:00 AM »

In order to be UL certified, I believe that it is now required that an MOV be located down stream of a fuse or that you use a newer type of MOV that has an internal fuse. It seems that MOV failures were causing more damage than the surges they were supposed to protect from. The fused MOVs sound like a wasted effort to me. If the MOV shorts, its internal fuse opens so now you have no protection but you don't know it. With the non-fused MOVs at least you knew to check the MOVs after you got the fire put out :-)

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KE4DRN
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« Reply #12 on: November 23, 2004, 04:40:08 PM »

The astron I repaired was purchased doa.

The fuse was blown, turns out only thing wrong was the mov was burned up !

Since the astron has a metal case I replaced the mov with one from mouser for under a buck.

I remember reading an article in QST about these surge strips and how many are not built to specs and have connections that are either loose or not made at all.

73 james

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K9KJM
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« Reply #13 on: November 26, 2004, 11:01:50 PM »

For really good information on protection, See the info at: http://members.cox.net/pc-usa/station/ground0.htm
And also the info on the Polyphaser Tech. Notes site:
http://www.polyphaser.com/ppc_pen_home.asp
Remember, No "device" is any better than the ground SYSTEM that it is connected to. Number 6 copper was considered nice and heavy back in the 1950's....  Today
plan on at least #2 or heavier, Better yet nice copper strap, Connected to a series of ground rods, spaced twice the distance apart as the depth (8' deep rods should be spaced about 16' apart) Bond ALL grounds together.
Properly installed communications tower sites nowadays take many direct lightning strikes and power surges from the AC line being hit near the tower with no damage.
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