» Power problems overview «

Introduction

Few people bar electricians give much thought to what's going on behind the ubiquitous white plug sockets in the walls…

… that it has separate attributes like it's current, voltage and frequency.

… that this is vulnerable to disruptions from the moment it's generated at the power station.

… all through it's torturous trip across the national grid.

… the overhead cables subjected to weather.

… underground cables battered by heavy haulage traffic.

… influenced by every industrial factory it passes.

… and when it miraculously reaches your house or office it is still subject to changes every time you turn anything electrical on or off!

A friend pokes fun of my constant attempts to use analogies to put things across to the layman, but I find it works. With that in mind, think of your computer as your home and the flow as a river, or a tide…

Ebb and flow, ebb and flow, ebb and - WOAH that's a big wave. Darn, my feet are soaking!
That's what your system feels most days. That's the wear and tear, or at worst a 'reset' for a change of clothes.

Ebb and flow, ebb and flow and flow Ye Gods, the river's burst it's banks!
Naturally the bigger surges are less often - for most people - but they always cause damage.

Ebb and ebb and ebb Ummm, what's it mean when the tide sucks out like that? and FLOW
Tidal waves, tsunami's, torrential floods, if you want to imagine what your computer feels in a major spike, imagine that coming down your garden path at you.

The only difference is that while most folk will thankfully never see or experience disasters like some of these, your computer isn't so lucky unless you protect it!

I don't know the true, current, statistics but here's a few older figures…

In the average year there will be around 235 fluctuations strong enough to damage your system
289 disruptive or destructive power disturbances a year.
[source: National Power Laboratory's 1990-1995 Power Quality Study].
One study by IBM claimed the average computer experiences around 120 power-related abnormalities a month. Another IBM survey put it at nearly ten times that!

Tempering the scare tactics is a lack of values or breakdowns associated, but however you look at it the threat is genuine. Only it's not a threat, it's a promise!

There are nine potential dangers to be aware of and, with the exception of complete power blackouts, your computer is likely to experience all of them in varying strengths - every single day. Several 'reliable' sources have different views about these are, or more specifically, how they break down. Below is the most agreed upon list.

So what are these hazards? Well…

Power failures (and blackouts)
Power sags
Power surges (spikes)
Under voltage - Brownout (sags)
Over voltage - (spikes)
Switching transients (spikes)
Line noise (interference)
Frequency variations (interference)
Harmonic distortions (interference)

As a gross overview:

Power failures and sags are drops in voltage which generally leads to unexpected lockups, data loss and reduced life expectancy for DVD-ROM's are the like. Memory is particularly sensitive to sags.

Power spikes are jumps in voltage which causes wear and tear, intermittent faults and, if high enough, outright destruction.

Interference doesn't so much affect the voltage as the frequency and stability of the current. These tend to be particularly hard on memory and communications and causes crashes, lockups, data faults and general wear and tear due to overheating.