My PSU died?

[westom]

What if the surge is induced in the wiring inside the building?

How often are surges created inside? The answer is easy. How many times a day do you replace less robust and damaged electronics such as dimmer switches, bathroom and kitchen GFCIs, and digital clocks? Where is this surge? A myth created to promote plug-in protectors.

If any appliance is creating a surge, the first thing damaged is that surge creating appliance. If any appliance is creating a surge, then the protector goes on the source - that appliance. Not on other appliances. More things not mentioned to promote more plug-in protector sales. Damning questions they hope you never ask.

A largest 'inside the house' surge generator is a UPS in battery backup mode. For example, this 120 volt UPS outputs 200 volt square waves with a spike of up to 270 volts between those square waves. Electricity so 'dirty' as to be harmful to small electric motors and power strip protectors.

And because protection already inside electronics is so robust, that same 'dirtiest' power does no damage.

So where is an internally generated surge? If that surge exists, the only protector that protects from all types of surges is a 'whole house' protector. The protector that earths lightning without damage also makes these lesser transients irrelevant.

And finally, anything an adjacent protector might do on a power cord is already accomplished inside every appliance. All appliances already contain robust protection. Your concern is a transient that can overwhelm that protection. That means a 'whole house' protector connected to superior earthing. That means no energy hunting inside the building.

 

[MfA]

You did mention lightning ...

Now I personally find close lightning strikes not statistically likely enough to worry about ... but still, EMP induced voltage spikes can't be arrested centrally.

PS. not all power supplies have MOVs in them.

 

[westom]

Now I personally find close lightning strikes not statistically likely enough to worry about ... but still, EMP induced voltage spikes can't be arrested centrally.

Nearby lightning strikes (EMP) are so destructive as to destroy every car radio, wrist watch, and cell phone in the area. These devices concentrate EM fields on the most sensitive part - the RF amplifier. Therefore damage is routine.

Oh. All those devices are not harmed? Well lightning struck a lightning rod. A wire to earth was only four feet away from a PC just inside the building. That was the entire lightning strike only four feet from the computer - that did not even blink. Even software did not crash. Protection that routine inside all appliances.

A long wire antenna suffered a strike some 30 feet away. That generated tens of thousands of volts on that antenna. Then an NE-2 glow lamp (also found inside lighted wall switches) connected the antenna lead to earth. Single digit milliamps conducted by an NE-2 reduced thousands of volts to ten. The NE-2 glow lamp hardly glowed. Why? Because protection from induced fields is that trivial.

Nobody said MOV are inside any power supply. Nobody said MOVs are necessary for protection. All power supplies already contain serious protection. And do not use MOVs to do it.

Nearby strikes (EMP) is made irrelevant even by a tiny NE-2 glow lamp. The nearby strike that does damage is a strike to AC electric wires down the street. That is a direct strike to every appliance inside the house - if a 'whole house' protector is not earthed.

Statistics - a destructive surge occurs typically once every seven years. A number that can vary significantly even within the same town. A number modified by environmental conditions such as geology. How often are surges in your neighorhood? Historical neighborhood data must include at least the last decade. Or automatically earth one 'whole house' protector because the solution is so significantly effective. Because the protector costs about $1 per protected appliance.

Earthing a 'whole house' protector to earth direct lightning strikes (and make lesser transients irrelevant) means protection inside household appliances is not overwhelmed. Means energy is not inside a house hunting for earth destructively via appliances.

 

[MfA]

Floating circuits inside metal boxes (car) or next to a metal plate (watch back) aren't exactly at risk and cell phone antennas are pretty damn small.

But I guess I overestimated the induced energy ... it always surprises me how large tesla coils do bugger all to computers and a relatively small Marx can be a menace too.

 

[Grall]

Great, my new place has no grounded sockets.

I experienced the same thing where I live. I ended up just pulling a thick ol' extension cord from a grounded socket in the kitchen to my computer workspace.

It happily runs 1 old Pentium4 box and 2 quadcore PCs with dual gfx boards in both of 'em, launch PS3, launch xbox 360, Wii, three flatscreens and two surround audio setups + various other junk (router, laser printer and so on), all on the same socket without blowing any fuses. Even a 900W microwave oven actually.

230W 16A wall sockets rock!

 

[homerdog]

I experienced the same thing where I live. I ended up just pulling a thick ol' extension cord from a grounded socket in the kitchen to my computer workspace.

I don't think my roommates would appreciate that. I might see if there's any way to have a grounded outlet installed in my room, but I don't see the landlords caring that much when they can't be bothered to get this green stuff out of our pool.

 

[stevem]

...but I don't see the landlords caring that much when they can't be bothered to get this green stuff out of our pool.

Do they also clean your bath/shower?

 

[homerdog]

If the shower had been full of green goo when we moved in they would've

 

[westom]

But I guess I overestimated the induced energy ...

They will often mention tens of thousands of volts on that antenna. Just forget to mention how easily that voltage is reduced. Too many know only because they heard something; do not first learn what it means.

Electricity can create strange problems with almost no energy - ie static electricity. Put a computer on a glass tabletop. If the motherboard is mounted to its chassis in multiple conductive points, then static electric discharge to various corners of that chassis (the computer sealed in its normal configuration). If a static discharge current must cross the chassis, then it also conducts across the motherboard. Motherboard ground is a large thin copper plate inside and across the entire printed circuit board. A static discharge to the chassis's outside means a voltage is created across that motherboard copper ground plate. Yes, a voltage difference end to end that can cause a computer crash.

How does that tiny current across a large copper plate cause a voltage difference? Same concepts that explain different voltages on the same wire antenna also creates voltages so high on a motherboard ground plane as to crash the computer.

Solution is to chassis ground the motherboard at only one point - typically where a power connection is made. Insulated standoffs everywhere else. Then no current is created by a static electric discharge to the outside chassis.

It's not so much about energy. It's always about learning the finer details of how electricity works. Many of these concepts are taught in the first semester to engineering students. So that a computer is more robust - so that a static electric discharge to its chassis is less likely to cause a computer crash - the informed assembler only makes one electrical connection between the motherboard ground and chassis ground.

Most will not learn how, when and why surge protection works. Many will only hear a soundbyte. Then only believe the first retail myth told. Most computer assemblers have no idea why a motherboard is best mounted with only a single point ground. And will argue using irrelevant (non-electrical) reasoning because they do not know how electricity works.

Even the mysteries of Telsa coils becomes obvious once these electrical concepts are first learned.

 

[Frank]

Switching power supplies work by shorting the incoming leads (repeatedly) through a coil, after which the energy stored in that coil is released into a capacitor. The peak voltages generated when opening and closing the switch can be pretty high, but because the combination of coil and capacitor is chosen to resonate at the switching frequency, those spikes don't pass through.

A capacitor is a conductor around it's resonant frequency, and a coil absorbs the energy as an electromagnetic wave around it's resonant frequency. The upper voltage both can handle is pretty much only determined by their isolation and capacity.

Such a combination is called a bandwidth filter, as it allows voltage fluctuations that have a (much) higher or lower frequency than the resonant one to pass through unhindered, but it blocks (at the exact frequency) or reduces (around that) everything else.

For surge protection, you want one that has a high-frequency resonance and large bandwidth. That way, all power surges are shorted, while your regular mains frequency passes through unhindered. And add a low-frequency capacitor to smooth things out at the end.

Most switching power supplies have such a filter on the primary (mains) side, to counter their own mains pollution.

Of course, there is a catch: you often need multiple of such filters in series, all with a different bandwidth, to cover the whole spectrum you want. They generally don't work very well if the load is really light. And they potentially could interfere with equipment, by generating a pulse train or starting an unwanted oscillation. And they're a lot more expensive than a simple varistor, which is all the surge protection you'll get in the bad, cheap ones. Which suck.