How to Choose a Surge Protector

Any surge protector must be able to divert the surge-energy at the moment it happens without being itself destroyed in the process and sometimes shorting the system (supply) to the ground!! If the shorting happens just after a surge, then you will have an unfortunate short circuit of the mains that needs to be fused or protected also! How do you protect against this kind of after surge permanent shorting to ground? By experience, and maybe due to some bad protection devices, I have seen fires started on the cables because of a permanent short circuit of the mains, to ground, before the mains could trip (bad design for sure, but also bad surge protectors...)

Is there an indicator to show its service life is over?.

I have fitted Type 3 surge arresters incorporating an audible alarm which sounds if the device has been called upon to do it's job (assuming it hasn't been blown apart in the process). This is the internal configuration:

How do you know whether it is still sound?.

If the equipment it is protecting is working and the device is silent, it is still sound.

If when power is applied the audible alarm sounds, the device must be replaced.

If the equipment it is protecting is blackened and smoking but the device is silent, it has probably tried to divert a current higher than its designed rating, and should be replaced.

GA westom - the joule ratings of surge suppressors give the amount of energy the suppressor is rated to divert to ground (as long as the ground is proper/sufficient as you stated). A surge in excess of the rating (or after the suppressor is damaged/destroyed) passes through to your load(s) plugged into it. So it appears that a higher rating is probably "better" and you will pay more for the higher rating. Kind of like "how much insurance for how much coverage do you want to buy". In general does not seem to make economic sense to buy the lower ratings.

I wonder if the warranty is worth anything ($20,000 yeah sure!) if the the manufacturer can claim poor grounding if equipment is damaged and the suppressor is not; or claim a surge beyond the rated energy if both the suppressor and the equipment is damaged. Anyone out there have any experience with claims?

> the joule ratings of surge suppressors give the amount of energy the suppressor
> is rated to divert to ground

Not quite. A protector rated at thousands of joules must divert hundreds of thousands of joules harmlessly to earth. 20,000 amps could carry a hundred thousands joules. Or four hundred thousands joules. A protector does not care. Relevant number is how much current it can carry, the time of that current, and how many times that current exists.

Current (not joules) is relevant to how a protect works during a surge. While earthing hundreds of thousands of joules, it might absorb a thousand joules. Just like a wire that conducts megawatts may also absorb hundreds of watts. Both work by diverting the flow of energy.

Protector with a biggest buck warranty is often a least effective protector. I have seen warranties state that a protector from any other manufacturer voids the warranty. That a manufacturer can void the warranty for any reason. And that the warranty is void if a building does not have a 'whole house' protector. Exemptions are numerous, extensive, and in fine print. Because those plug-in protectors are being marketed to the least technically informed.

GM has one of the best warranties. Does that prove GM products are superior to Toyota, Hyundai, and Honda? Of course not. Best warranty is often an indicator of worst products.

We had an American 450kW heating system installed where the Earth was used as Neutral. Star system too. Kept blowing inverters downstream because of current and voltage induced in parallel-run earth conductors (35mm) on the same trunking.

Eventually found the missing link and connected the neutral. Problem solved!

Also fitted Phoenix Contact surge protectors. Highly recommended! No business connection..

Ref: Allen Bradley.

Surge protectors are in real sense surge killer or surge blocking devices that prevent surge voltage or surge current damaging the real equipment for which they need to protect. Such devices let the equipment function normally even if surge exists.

Tripping devices are not surge protectors. Look for more information on website www.littlefuse.com/

http://www.littelfuse.com/products/Technology/Varistors/search.html

http://www.littelfuse.com/products/Technology/Resettable+PTCs/search.html

PTC, Varistor and surge protection Zener diodes are very common and some time discharge vacuum/gas filled tubes are also used.

http://www.littelfuse.com/silicon-protection-diode-arrays.html

> Surge protectors are in real sense surge killer or surge blocking devices that

> prevent surge voltage or surge current damaging the real equipment ...

Any protector that works by blocking or absorbing surges is ineffective. V-I curves for varistor, GDTs, avalanche diodes, etc should make that obvious. Hundreds of thousands of joules must dissipate somewhere.

Protection is always about where energy dissipates. An energy absorber is the protection. Completely different from a protector. Protectors either connect (divert) energy to protection. Or do nothing effective. An MOV with the always required low impedance connection to earth will not protect from destructive surges. How to make every varistor better? Upgrade the only thing that does protection - the energy absorber - single point earth ground. And make that connection shorter (lower impedance; not just lower resistance).

It all depends on your application and scheme of the design.

ESD protection is now in-build in most of the communication ICs and industrial ADCs. These do work well for specifications.

I do use some or other protection mechanism in all high voltage power supplies.

There are ultra low leakage current protection device in amplifiers and high energy devices in power electronics. There is no one right device for all applications.

Discussions of generalized type always have problem as there is no specific goal.

During a flood, protection is a downstream river path. Make it bigger, straighter, or deeper, and the town has better protection.

Use filters or separation like a town's dike. A dike does not provide protection. It simply makes the actual protection better. Performs a supplementary function. If the river can rise higher and still not flood the town, then the dike has supplemented protection. River can carry even more of a flood harmlessly downstream. But without that downstream path, a dike is useless.

Make a river deeper or wider by installing more protectors connected shorter to what absorbs the flood or surge. IOW increase protection by locating protectors closer or shorter to earth – lower impedance. Increase distance between protector and electronics. Increased impedance between electronics and the protector is the equivalent of the town's dike. By itself, increased impedance (a blocking device) cannot provide effective flood / surge protection. But in combination with a deeper / wider river, then the dike can make flood protection better. By increasing impedance between electronics and the protector (a higher dike), then more of a surge will flow to and be absorbed by earth ground (or whatever provides protection by absorbing energy).

Varistors, GDTs, avalanche diodes, etc cannot operate as the dike - to block or absorb surges. These devices operate like the deeper or wider downstream river. Increased impedance (more separation between electronics and protector or by using filters) can only supplement protection (like a dike) by doing a minor blocking function.

Even ESD protection inside semiconductors is about diverting (not blocking) a surge. That protection function exists only when the semionductor is part of a system where energy dissipates elsewhere. A semincondutor disconnected from the system no longer has that ESD protection to divert current elsewhere.

Blocking is not useful without the always other path to divert current. That other path is what varistors, GDTs, avalanche diodes etc are for.

Instruments install ESD protection and not lightning protection.

Protection from high surge current from lightning bolt and EMP induced emf requires special consideration and generally high end systems do consider all these protection. However, these are yet to reach home. These technologies are with defense and also with aircraft manufacturers, with space agencies.

I think it is worth exploring details of such requirements first and then one can look into related information.

Gas tubes were used to divert excessive voltage energy into Earth path in TV antenna amplifiers. There are no possibilities of having such excessive energy discharge devices to digest entire energy of the thunder bolt. However, we expect limited energy actually passing through entry points exposed to get in direct contact with lightning energy source.

Low cost low gas filled discharge tube based devices that can handle high surge current and having no loss or tolerable loss in normal condition are most acceptable devices.

Hi Moose:

I am looking at a move to Belize and have discovered that they have been suffering from power surges that even "not cheap" surge suppressors are not handling.

What are the technical criteria that differentiate the good ones from the bad ones?

Many people have lost motherboards and other components and the utility seems unable to regulate the voltage - while disavowing any liability for the consequences.

Is there a heavy duty voltage regulator available for this or should I be looking at a 'bucking and boosting' transformer for my home electrical service?

Any ideas appreciated from CR4

D

> What are the technical criteria that differentiate the good ones from the bad ones?

Was posted previously for reason after reasons after what you view. No plug-in protector does protection. Does not claim that protection. Is a profit center for those who let salesmen, propaganda, and advertising strip them of their money.

See the word 'no'? They are learning that in Belize the hard way.

Where do hundreds of thousands of joules dissipate? Not inside a protect*or*. Dissipates in protect*ion*. A protect*or* not connected short (ie 'less than 10 feet') to protect*ion* is ineffective. NIST makes that point bluntly:
> A very important point to keep in mind is that your surge protector will
> work by diverting the surges to ground. The best surge protection in
> the world can be useless if grounding is not done properly.

Single point earth ground. And low impedance connection to that ground. Not low resistance. Low impedance means no sharp wire bends, no splices, wire not inside metallic conduit, and as short as possible (ie 'less than 10 feet').

How it quickly identify ineffective protectors. 1) No dedicated wire for the always required short connection to single point earth ground. 2) Manufacturer avoids all discussion about earthing. May even try to confuse safety ground with earth ground.

Go back and read that post. Others in Belize have apparently seen the examples of protectors that do not even claim surge protection. Described in that post is how to identify ineffective and effective solutions. Notice what honest recommendations provide - the numbers. What we all learned from Saddam's WMDs. What happens when we ignore hard facts and numbers.

Anything you install to stop or absorb a surge is best called a scam. Impossible. And exactly what was not done for the past 100 years to have even direct lightning strikes without damage.

While employed by Telkom (RSA) they started by using carbon electrodes separated by a mica plate with some holes in it. They changed these to "Plug In" gas surge suppressos that fired at 350V. Oops. Lightning struck a tree in the middle of the town.

Surge suppressors wers charcoal. Telephones exploded. Literally. Stay away from the stove or the phone and unplug all connections to the PC when there's a thunderstorm!!!

So they replace protector that were obsolete so many generations ago with protector that have since been made obsolete less generations ago. Then suffered damage. At what point does it become obvious. The failure is directly traceable to completely uniformed 'experts'.

Meanwhile, all over the world, direct lightning strikes is routine without damage.

An example of how surges obtain earth ground without damage:
http://www.crh.noaa.gov/pub/ltg/plane_japan.php

Damage from direct lighting strikes is traceable to human error (or one who did not first learn the well proven science). Using obsolete technology due to insufficient knowledge. Then suffering damage proves what? Nonsense.

Routine is to have direct lightning strikes to commercial broadcasting stations and munitions dumps without damage. Many learn from science rather than parables.

westom,

Faraday cage protects planes from lightning, is well known now.

I think lightning protectors are being installed in homes at likely thunder bolt entry point such as antenna, power line input. It is still not a widely used technology. Perhaps at many places on earth people do not believe that they may be hit by thunder bolt.

Shorting of three phase power line have resulted into injection of more than 500V into my house circuit and to all houses nearby those were on same connection scheme. It did cause damage to many of my systems that included TV, FAX, Fridge. However, inverter and battery backed systems were not damaged as inverter worked well to protect against excessive input power. I am not sure if this device would have protected against thunder bolt hitting my home.

There was a case of damage of instruments to the tune of millions of dollars in lab due to induction heating furnace radiating energy and it being picked by the sensitive electronics.

If you all recall the story of that Fox bat fighter plane from Russia being flown away and investigated by the USA agencies as bill s**t technology has shown that some people were smarter than others much ahead in time.

Protection sure is of great concern and all engineers must learn methods to achieve best possible results and perhaps in lower cost.

If you know how things can get damaged, you have a chance to work on how to protect things. Science and technology go hand in gloves.

Why was a 707 over MD destroyed by lightning? Why was a 747 leaving Spain destroyed by lightning? Because that Faraday cage is incomplete. And because internal circuits essential to 'diverting' surges were missing.

Virtually every airline has suffered at least one direct lightning strike. Routine is to have direct lightning strikes without damage.

A Faraday cage would do what protectors must also do. Divert that current safely on a non-destructive path. No way around it. Since airplanes (like cars and electronics) do not provide sufficient Faraday cages, then surge protection is still and always about diverting current so that voltages and damage are not created. Planes are routinely struck because surges are diverted - not stopped or blocked. Direct strikes without damage is routine.

Anything that might stop or block a surge (lightning, ESD, etc) is ineffective protection. For homes, that means each protection layer is the single point earth ground.

OP asked about protection that would trip, open, or block a surge. Cannot happen. Fuses do not stop surges. Anything that would protect by disconnecting is a myth; not possible. Protection is always about diverting current without creating a destructive voltage. How it works even in semiconductors. So that massive energy dissipates harmlessly elsewhere. Protection is always about where energy dissipates.