Surge Protectors - Limited Lifetime??

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eorange

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So last week I was using the computer, and the computer / speakers started going haywire, followed by lots of smoke pouring out from my surge protector. The computer was OK, but my APC surge protector burned up pretty good. This was no dinky cheapo APC unit either (rated at ~3400 joules). We had no huge power surges or any other problems that were apparent.

So here's what I found out from the guy at Best Buy, and later as I googled surge protectors:

A surge protector's capacity is rated in joules, as most of us know. But that is over the LIFETIME of the surge protector.

I had mine for 5 years, and over that time it had absorbed many small surges. Each time that happens, its capacity for absorbing surges goes down. You normally think of it protecting against a giant lightning strike. But it had absorbed enough small surges that its capacity was now zero.

And then it finally died. At that point, surge protectors could just open up and stop providing power, or start burning, which is what mine did. The guy at Best Buy told me you need to replace surge protectors every 2-3 years, which made me skeptical. But as the surge protector absorbs periodic (small) energy surges...some component is apparently abosrbing this energy and wearing down.

So now I am looking at UPSs (good idea anyway), but of course they all come with "surge protection" - will THAT eventually be whittled down to nothing over time?

Looking for thoughts and opinions. Is this an accurate portrayal of surge protectors?
 

kb2vxa

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That's one of the reasons why I stated in another thread that they should never be trusted to do the job you expect them to do. The worst case scenario is when they fail without any indication they have left you with zero protection, if they smoke up or pop the circuit breaker consider yourself lucky.

There are several types available (Google for details) each having its own peculiar characteristics and applications, the metal oxide varistor (MOV) being the cheapest and most common, unfortunately it is the least reliable. As usual when I'm called upon memory fails but I've heard of a new type similar to the MOV characteristically but far more reliable. I just ran a quick search and drew a blank, maybe you have a bit more patience if you have the interest.

"Is this an accurate portrayal of surge protectors?"
Pretty much, look it like a machine gun firing at a cinder block wall. Each bullet does little damage but it adds up and the wall is no more.
 
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The very same reason that you need to follow good ESD practices when working around IC's and other small stuff, those yellow stickers are there for a purpose.
 

n5ims

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So now I am looking at UPSs (good idea anyway), but of course they all come with "surge protection" - will THAT eventually be whittled down to nothing over time?
In one way, yes, it will eventually be whittled down do nothing over time. A UPS works using a rechargable battery (lead-acid gel cell in nearly all cases) which will stop holding a charge over time. Most good UPSs have an alarm that will sound when the battery is about to die though so it can generally be swapped out prior to it totally failing. The battery failure will only cause a loss of power during a power outage anyway so unless that UPS is doing critical duty this shouldn't cause any major issues.
 

Thayne

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In my experience with lots of MOV type surge suppressors, they keep working until a big hit or voltage surge takes em out in a big blaze of glory or a small puff of smoke.
Of course when they do that they may or may not save whatever is connected to them. Most man made electronics cannot take a direct lightning strike, but I have seen MOV's blow and that causes the fuses in series with the power supply to open in time to save the equipment.
Somewhere I have some pictures of some wall mounted mov's that blackened a whole wall and splattered the room with blobs of molton metal & plastic. I will try to find them.
 

kb2vxa

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The blobs of molten metal or the plastic? (;->)
Eh, funny you should mention a fuse blowing in time to save the equipment when it defies the laws of physics. The event timing is such that we have developed certain phrases that apply like "the transistor was invented to protect the fuse".

Sorry guy but you have it all wrong, it was sheer luck that protected the equipment, the fuse is there to protect the line, not the device connected to it. Think of it this way, when the MOV shorted dumping the current to ground or neutral (depending on which one caught the surge) what would have happened to the line had the fuse not blown? Same for any appliance, a short by its low resistance nature will draw all available current to itself and make a royal mess upstream.

OK, the branch circuit breaker may have tripped before a fire started, maybe not, but that's not why the breaker is there either. Like the fuse only on a larger scale its purpose is to protect the mains from the huge available current should the house wiring develop a short, again not the other way around.
 

eorange

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Thanks for all the info. Good reference for things I would have never thought about.

Aargh, nothing is simple (or cheap!). I will probably end up getting the same APC surge protector, but remember to replace it after 2-3 years.
 
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