Author Topic: Power strip, a global demand, any recommendations?  (Read 16085 times)

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Offline saturation

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Re: Power strip, a global demand, any recommendations?
« Reply #25 on: March 06, 2012, 02:06:21 pm »
A well made PSU for most devices can take more abuse than most folks know, and there is logic to having your device die from a surge rather that risk a fire from MOV overload; a poorly made surge protector is more a risk than a power strip, which is simply a set of conductors, circuit breaker and a switch [ just make sure they all look properly rated for load], I open strips and all my surge protectors and confirm they are well made and if a power strip alone, there are no MOVs in side:

http://www.avsforum.com/avs-vb/showthread.php?p=15356579#post15356579

Triplite used to be a great name in surge protectors, but after sampling there new isobars made in China they are made so badly, I wouldn't consider them in the same league as APC, which so far has been consistent since 1990s.  I have not destructively tested any of them but just gauge their worth based on the assembly of the units and the 2 APCs that have actual died in surges.




I'm really not keen on having surge protectors in power strips for a few reasons:
  • Combining the two means you'll be making compromises with both
  • I hate the idea of having distributed fire starting boxes around my house
  • In London, power is very, very clean in terms of surges and overvoltage. The maximum overvoltage we have had is around 12V in the last 2 years. I don't measure for quick transients, but have no reason to suspect there are any. Benefits of underground cables.
Best Wishes,

 Saturation
 

Offline jahonen

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Re: Power strip, a global demand, any recommendations?
« Reply #26 on: March 06, 2012, 05:18:26 pm »
It should be remembered that any device that is connected to two different ports, like an ADSL modem or so, it connects to electrical network and phone line. It can still be destroyed even if protected by SPD, if enough voltage develops between phone line and mains earth. Or if there are two computers interconnected via ethernet or something like that. It is imperative to ensure that those will see the same potential in event of surge.

So for that reason, I tend to think that proper surge protection is more system level issue, than per device issue.

I prefer at least two stages of surge protection, one heavy duty at distribution panel (levels 1 & 2), and then finer and faster near the equipment to be protected (level 3). Idea is to absorb bulk of the surge at beefier device. I had a close call last summer, a lighting stroke nearby and I heard a sharp snap from somewhere in mains outlet. We have underground low voltage 400 VAC cabling, but "mid-voltage" 20 kV distribution is mostly above ground. However I haven't observed any damage so far. After that I decided to have that distribution panel level SPD installed (levels 1+2 combo), a Phoenix Contact FLT-CP-3S-350. Although that is relatively expensive, it is still quite cheap (few hundred euros) when compared to most electronics devices, or some measuring equipment which can be easily destroyed by a surge pulse. Good thing in centralized SPD is that it ensures that ground potential will rise equally at all mains outlets, thus reducing damage potential for interconnected devices.

I know one case where our customer at work wondered why their equipment broke down at regular intervals at industrial building, it turned out that all breakdowns stopped when SPD was installed. It is not the mains frequency overvoltages that matter, but those microsecond-level surge pulses, which can reach levels of kV's. Switching large loads will generate surge pulses in mains.

Regards,
Janne
 

Offline saturation

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Re: Power strip, a global demand, any recommendations?
« Reply #27 on: March 06, 2012, 09:05:28 pm »
Yes, your recommendation is the preferred method, jahonen.

I'm not sure if I linked this before, but here is a layperson geared brochure on total home protection, which incorporates level of protection at various junctions, from the supply line, distribution panel to the wall socket.

How much you need really depends on your risk for surges: where you live [ lightning prone or not]  inductive loads at your location or nearby enough to couple into your wiring. 

http://publications.usa.gov/USAFileDnld.php?Pub=pdf1329.pdf&PubID=1329&httpGetPubID=0&PHPSESSID=48kqd2tbjq3kp7t75qvvu90io4

One thing that is often overlooked is EMF coupled into your structures wiring, it can induce surges that bypasses all mains protection, and thus the plug-in types are your last level of defense.   Coupled EMF can enter through any lines: CATV or POTS telephone lines, even if the companies that provide such services already have system wide surge protection.

A practical problem is choosing a reputable surge protector, because you have to take it on faith that the maker makes good products, or do your own tear down analysis, since the only time you may know its not well made  is when it fails to provide protection.

Folks who live in apartment complexes may not have to worry about surges, as many modern buildings provide whole building protection, but it can't hurt to have your own for those expensive items like large screen TVs or against EMF or inductive surges caused by other occupants.




It should be remembered that any device that is connected to two different ports, like an ADSL modem or so, it connects to electrical network and phone line. It can still be destroyed even if protected by SPD, if enough voltage develops between phone line and mains earth. Or if there are two computers interconnected via ethernet or something like that. It is imperative to ensure that those will see the same potential in event of surge.
Best Wishes,

 Saturation
 

Offline sonicj

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Re: Power strip, a global demand, any recommendations?
« Reply #28 on: March 08, 2012, 12:03:21 am »
my ex gf called me up wondering why my tv wouldn't come on.  so i checked it out and this is what i found... one mov failed closed and a blown hrc fuse. the rest of the components "survived", but instead of repairing i tossed the board and converted it into a 15a power strip. saved my 40" xbr, but two powered monitors (audio) were not so lucky. could have been unrelated though, as they have been known to have faulty power supplies. also not sure what she had the monitors plugged into. looks like the polyamide contained a good bit of the blast.  anywho...
-sj
 

Offline GeoffS

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Re: Power strip, a global demand, any recommendations?
« Reply #29 on: March 09, 2012, 06:29:55 am »
Power strip:
according to Wiki.org,(http://en.wikipedia.org/wiki/Power_strip) "In 1972, the electrical "power-board" was invented by Australian electrical engineer Peter Talbot working under Frank Bannigan, Managing Director of Australian company Kambrook. The product was hugely successful, however, it was not patented and market share was eventually lost to other manufacturers."
I've seen some really good designs yet still am using traditional old ones.

Just for the youngsters, here's one of the original Kambrook powerboards. 
I've had this one since the mid 70's and it's still in use in the shed. The neon indicator stopped working long ago but otherwise, it will outlast me.  :)
 

Offline saturation

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Re: Power strip, a global demand, any recommendations?
« Reply #30 on: March 11, 2012, 02:58:04 pm »
Don't get too many post-mortems of SPDs blowing. 

Who was the maker of the SPD?  Do you know where the surge may have come from?


my ex gf called me up wondering why my tv wouldn't come on.  so i checked it out and this is what i found...
Best Wishes,

 Saturation
 

Offline SeanB

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Re: Power strip, a global demand, any recommendations?
« Reply #31 on: March 11, 2012, 08:08:46 pm »
I have has MOV's as add ons for many years, and have had a few fail short circuit in that period. Luckily here the MCB has ruled supreme since the 1960's and earth leakage ( GFCI to the USA) has been a standard since then, only way you will not have one is if you bought a house in 1960 and never had any electrician out, or never replaced a socket outlet or light since then.

When they fail it just trips, and I need to go around and pull plugs until the circuit will reset, then replace the MOV's in the plugtop with new ones. They have saved a lot of equipment over the years from damage, even after lightning hit the building next door and blew a lot of electronics, never even knew anything had happened until I saw the pile of crisp at the bins. Dial up modem went through a surge suppression plugtop as well,  it provided 2 levels of voltage protection to the phone line as well as more mains overvoltage filtering. I have a similar one on my ADSL line still, from old modems where the users refused to plug in the 2 leads to get the phone line protection, and had overhead phone lines. Might account for some of the 23.5 dB attenuation on the line, but still have a lot of margin. The record I know for that is lightning hit over 40km away and blew the entire exchange out. No phones for 2 weeks while it was ripped out and replaced entirely, nothing survived.
 

Offline sonicj

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Re: Power strip, a global demand, any recommendations?
« Reply #32 on: March 14, 2012, 04:30:18 am »
Don't get too many post-mortems of SPDs blowing. 

Who was the maker of the SPD?
Monster Cable PowerCenter AV800

Do you know where the surge may have come from?
lighting is very common here in Florida. most likely the source imo...
-sj
 

Offline saturation

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Re: Power strip, a global demand, any recommendations?
« Reply #33 on: March 14, 2012, 03:13:26 pm »
Thanks sonicj; I've had 2 failures in my lifetime with a SPD, once in a Florida motel and another in the Pacific but never from Washington DC to Toronto.


Don't get too many post-mortems of SPDs blowing. 

Who was the maker of the SPD?
Monster Cable PowerCenter AV800

Do you know where the surge may have come from?
lighting is very common here in Florida. most likely the source imo...
-sj
Best Wishes,

 Saturation
 

Offline PaulS

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Re: Power strip, a global demand, any recommendations?
« Reply #34 on: March 20, 2012, 11:09:15 pm »
On the subject of power strips, my Isobar has 3 different levels (50db, 75db, and 100db). Is there any real difference between these?
 

Offline SeanB

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Re: Power strip, a global demand, any recommendations?
« Reply #35 on: March 21, 2012, 11:00:33 am »
First level is the incoming supply after the filter, between 1 and 2 they added an extra common mode choke assembly and so on for 3. They might have added extra X capacitors and MOV's in each stage, but they are limited in how much Y capacitors they can add before it will cause nuisance tripping due to earth line current.
 


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