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jwil1
22-06-2008, 02:48 PM
Are SPs connected to PC's overrated?

In other words, should I get one - and if so, what should I protect?

I have 1 new PC, 22" monitor, home network switch + a few other cheap devices (speakers, lamp) and a few old machines that probably don't need protection.

These are on a powerboard with a overload switch on it - I assume this is different to a SP?

TIA

Speedy Gonzales
22-06-2008, 03:11 PM
It depends if the power board says surge protection on it.

If it does, it'll do the same thing. If it doesnt then no its not the same thing

rob_on_guitar
22-06-2008, 03:17 PM
Its a nice to have, and generally they work. Id rather have my adapter pop then my pc.

jwil1
22-06-2008, 03:17 PM
Also, How reliable are they??

My block is an uber-cheap $10 8-way powerboard (HPM brand). Probably 3-4 years old. So I don't think it has a SP built in.

beeswax34
22-06-2008, 05:18 PM
I just have a Belkin surge protector which has 4 plugs on it. It costs $130 but I got it free but it works well and there's no harm in using one is there?

tweak'e
22-06-2008, 06:26 PM
Also, How reliable are they??


that a good question which no one really has much of an answer.

not many tests of them have done that i know of. consumer mag did a good test years ago and found a lot didn't do anything.
most likly the cheap ones won't do anything much BUT some of the exspceive ones are not any better.

i've pulled some $100 + ones apart to find the same bits in them as a $20 one.
i've seen some that where labbelled "will not potect over xyz voltage" if i remeber correctly that voltage was actually the PEAK voltage for 240 mains. so its a fancy way of saying it doesn't do jack :horrified

also just recently was shown a MOV block that plugs into a spare fuse block on the switch board. its meant to protect the house but i doubt it do jack. it didn't have any indicators on it to tell you if its "used up" or not. so the first stike kills it, the 2nd kills your gear.

it get the fealing that surge protection in NZ is just a con job dispite there being some excellent products on the market. tho we do miss out on some which are common around the world.

a good basic setup you can do is fit a lightning diverter on the incoming mains line. it only works on high voltages, won't do anything with below 1000v's but it wil take the big hits so your cheap surge protectors can survive long enough to actually do something.

pine-o-cleen
22-06-2008, 08:06 PM
Your right tweak'e, most of them wont do anything. They are designed to protect against surges that are so small, that they lie within the tolerances of most appliances. Big surge comes....whammo bye bye surge protector and bye bye appliance.

The best thing to do is disconnect appliances during storms, which is when surges are most likely to occur.

In saying that, I thought I'd better do some research before I ranted, looked on the PDL website and these: http://www.pdlglobal.com/data/product_documents/955_datasheet_document.PDF

..seem to be rated quite well, but who knows how much they cost.

Billy T
22-06-2008, 09:50 PM
Surge protector is really a mismomer in this application, especially if solely reliant on MOVs (metal-oxide varistors, otherwise known as voltage-dependent resistors or VDRs).

A surge is a rise in voltage of relatively lengthy duration (milliseconds to seconds or more) and within reason they are not particularly harmful to computers because most computer power supplies can easily withstand surges of up to 15-20%, and the NZ power system does not produce many surges of any significance.

MOVs do not respond to such surges because their breakdown voltage is much higher and since most "surge protectors" are nothing more than MOVs they are largely a waste of money from that perspective.

What will cause major problems are voltage spikes and these can easily reach thousands of volts. MOVs are effective in clipping these transient voltage excursions down to levels that will cause no harm, but every spike that hits an MOV erodes part of the core material away and in time the MOV will cease to be effective. Unfortunately you rarely have any way of knowing when your MOV(s) stop working, but they should last several years in a domestic environment.

There is only one "surge protector" on the market (that I know of) that can tell you when it is about to give up the ghost, and it does that by having multiple MOVs in a two stage filter system configured so that when the first stage made up of several MOVs in parallel finally dies, a green LED goes out to indicate that all primary protection has ceased. You then have a few days, weeks, or months, depending on how spiky your power is, in which to replace it before the single MOV that provides the secondary protection is expended. It is not cheap!

Surge filters built into the average power board are useful for spikes only, but give no warning when time expired!

Cheers

Billy 8-{)

tweak'e
22-06-2008, 10:28 PM
......... but they should last several years in a domestic environment.


hate to disappoint, but most are one shot wonders.

majority of them are single MOV or at best MOV. for any decent protection you really need banks of them.
some of the USA ones ive seen advertised look good. multiable banks, indicator light per bank, mounted externally to the house with earth peg directly underneath.

mind you thats where a diverter is quite good, don't try to handle the spike just dump it directly down to earth. a crude homemade version is a spark plug !

also a lot of sentive appliainces have there own MOV's built in.
i've repaired a fair few over the years. a small catch i've come across is people have a blown fuse in the applaince but fail to check the MOV in it. generally its fried and they only replace the fuse. months later applaince is faulty with major circut board tracks blown off it !

feersumendjinn
22-06-2008, 11:33 PM
Wainuitech has had some experience with these and UPS's.
http://pressf1.co.nz/showthread.php?t=89627&highlight=surge+protection

Burnzee
23-06-2008, 11:22 AM
Hi JWi

To answer your questions, repeating the information I wrote in an thread sometime ago might be helpful.

1. SPIKES and SURGES are temporary increases in voltage. A Spike lasts less than three billionths, (3 nanoseconds) of a second. A Surge lasts three billionths of a second or more.

2. Most Surge Protectors available in New Zealand use METAL OXIDE VARISTORS, (MOV'S). These are great but are not bulletproof and will break down after a while. These do not absorb the Spikes or Surges but divert them to ground.

3. Surge Protectors are not created equal. All MOV's look like a round component, (normally blue), with wires attached. This does not indicate the switching speed, maximum voltage before breakdown etc.

4. Cheap ones use a single MOV while more expensive ones use a more than one.

5. The more expensive Surge Protectors also use TOROIDAL CHOKES. These are coils of wire around a magnetic former. Their purpose is to condition the power supply thereby feeding a more constant voltage to your gear.

6. The Manufacturers Insurance is a good indication of the confidence in his product. Don't buy one without it.

7. Whilst lightning and power cuts are sources of Surges and Spikes, they tend to be in the extreme. Domestic heavy appliances, such as ovens, washing machines etc switching on and off are another source. Make no bones about it. These are doing your gear harm too but more slowly.

8. The more expensive ones also incorporate a backup FUSE. This is not a thermal cutout or a piece of wire. They use a RESISTOR. This burns out if the MOV's are unable to complete the job, thereby saving anything connected to the Surge Protector. The Resistor is monitored by LED/S thereby giving a good indication of protection.

9. The more expensive ones also have more than one plug outlet. This allows you to protect more than one piece of equipment, ie a computer, printer, modem etc.

10. The more expensive Surge Protectors also protect your computer gear from Surges and Spikes on the telephone wire.

11. Do they work? They certainly do. We had a branch fall across our power line. All my gear hooked to Surge Protectors survived. Stuff like a microwave oven and a cellphone charger were stuffed. Both were plugged in directly but weren't in operation a the time. The fridge threw the towel in too. Neighbors in the area were affected in a similar way.

12. Finally, the more expensive Surge Protectors will self-sacrifice if need be. This is not a design fault but is by design. What is more expensive to replace your computer gear or the Surge Protector?

That said, what Surge Protector should you buy? Answer: The most expensive one you can afford. You can't afford anything less!!


That said, lets look at some of the issues because Surge Protectors are a hotly debated subject on Press F1.


hate to disappoint, but most are one shot wonders.


Yes, they are but as explained above this is by design.


A surge is a rise in voltage of relatively lengthy duration (milliseconds to seconds or more) and within reason they are not particularly harmful to computers because most computer power supplies can easily withstand surges of up to 15-20%, and the NZ power system does not produce many surges of any significance.


This may be true but I have replaced a string of computer power supplies that can testify to how bad New Zealand's power supply actually is. In the Wellington area, our grid doesn't seem to be as reliable as it once was. I know there is a legal requirement for the power supplier but that is my general observation. It will get worse if the looming power cuts actually occur.


Your right tweak'e, most of them wont do anything. They are designed to protect against surges that are so small, that they lie within the tolerances of most appliances

As outlined above small surges are still damaging your sensitive equipment but more slowly.



In other words, should I get one - and if so, what should I protect?


Bet yah boots, yah should. As outlined above get the most expensive model/s (from a reputable Manufacturer), you can afford. Protect all your sensitive gear like computer gear, LCD tv's, stereos etc. Get one that protects the phone line input too. This will protect your phone, modem and wireless router from any nasties coming in that way too. Do not get a cheap model. These are useless.

BURNZEE

tweak'e
23-06-2008, 12:20 PM
hate to disappoint, but most are one shot wonders.
Yes, they are but as explained above this is by design.


most of the basic ones on the market do not do it by design. theres no fuses/cutout etc. the better ones will generally handle mulitable big hits without blowin.
good example is the microwave of yours that blew. generally they have their own built in MOV's + fuse.

one of my early ones i bought for more than $100, when i opened it its was nothing more than single MOV + fuse. yet my $200 one has more than a dozen MOV's + TOROIDAL CHOKES.
some are simply complete rip offs. thats the catch, how do you tell without cutting the thing open and seeing how its made.

Billy T
23-06-2008, 04:28 PM
This may be true but I have replaced a string of computer power supplies that can testify to how bad New Zealand's power supply actually is.

I do a lot of power monitoring (logging voltage excursions and spikes) and I do not find NZ's power supply to be bad at all. However, although it comes in relatively clean, users tend to mangle it on site. Go back to the supply transformer and it is usually ok.

Modern computer power supplies are not all that flash and I suspect they are built to a price in anticipation of a service life of only 3-5 years. Electrolytic caps that dry out and overheated solder joints on wire-wound resistors are big killers. I have an ancient Compaq power supply taken from a 386 that is still doing sterling service in my P166 machine. it must be at least 12-13 years old and runs all day every day.


As outlined above small surges are still damaging your sensitive equipment but more slowly. It is relatively rare for incremental damage to occur to electronic equipment, it usually survives or dies, there is rarely a halfway house. Putting it another way, they are either OK or dead, there is no real halfway option.

Cheers

Billy 8-{)