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Old 12th June, 2004, 07:54 PM
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A power drop is exactly that, a reduction in the amount of available power. A power outage is a complete lack of power.

The reason a drop can be worse than an outage is because when you have a power drop, you make things work harder to produce the same amount of power. For a PSU, this translates to increased heat in the components and increased load on the circuits to produce the same amount of useful work. In the US, most things are designed to work down to 95v, because this is the level that the utilty companies have to provide as a bare minimum under brownout or power drop conditions. This would be all find and dandy, except that the utility only has to deliver that level to the meter. Many buildings (especially older ones) have poor wiring, to the point that when the electric company has a brownout and delivers 95v to the meter, the actual voltage delivered to the socket can be as much as 10v lower than that, because of the wiring. Now you've got things running at voltages they were never designed for, and things start blowing up. Hence, a power outage can actually be better for the electronics than a power drop.

Generally speaking, any equipment that is sensitive to voltage fluctuations should be on a line conditioner. A line conditioner is similar to a UPS except it doesn't have battery backup. It 'evens out' the surges and brownouts to provide regulated power to the load, and shuts down completely if the input power drops too far.

The next step up from this is a UPS, which performs the same functions, but also has a battery of come capacity to allow it to handle power failures.
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