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| 5/24 |
| 2002/1/25-26 [Science/Battery, Science/Electric] UID:23665 Activity:very high |
1/24 How do UPS's (uninteruptible power supplies) work?
\_ trained hamsters inside only run when they see the little
light go out.
\_ Damn, products evolve almost too fast these days. My old
version only uses rats.
\_ Big rechargeable batteries.
\_ They sit between your box and the power grid, and are supposed
to figure out when there's a drop in power, and then kick in
within a short enough time to prevent the connected device
from powercycling or experiencing damage. Some also do surge
protection, or are controlled by the protected machine itself
(so for example when the charge is very low, they tell it to
nicely shut itself down.) -John
\_ More like "conditioned" power. Drops are just as bad as spikes.
\_ http://www.howstuffworks.com/question28.htm --erikred
\_ That's a GREAT web site!!! -- yuen |
| 5/24 |
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| www.howstuffworks.com/question28.htm A computer can tolerate slight differences from this specification, but a significant deviation will cause the 39 computer's power supply to fail. A UPS generally protects a computer against four different power problems: * Voltage surges and spikes - Times when the voltage on the line is greater than it should be * Voltage sags - Times when the voltage on the line is less than it should be * Total power failure - Times when a line goes down or a fuse blows somewhere on the grid or in the building * Frequency differences - Times when the power is oscillating at something other than 60 Hertz There are two common systems in use today: standby UPS and continuous UPS. A standby UPS runs the 40 computer off of the normal utility power until it detects a problem. At that point, it very quickly (in five milliseconds or less) turns on a power inverter and runs the computer off of the UPS's battery (see 41 How Batteries Work for more information). A 42 power inverter simply turns the DC power delivered by the battery into 120-volt, 60-Hertz AC power. In a continuous UPS, the computer is always running off of battery power and the battery is continuously being recharged. You could fairly easily build a continuous UPS yourself with a largish battery charger, a battery and a power inverter. The battery charger continuously produces DC power, which the inverter continuously turns back into 120-volt AC power. If the power fails, the battery provides power to the inverter. Standby UPS systems are far more common for home or small-business use because they tend to cost about half as much as a continuous system. Continuous systems provide extremely clean, stable power, so they tend to be used in server rooms and mission critical applications. Here are some interesting links: * 43 How PC Power Supplies Work * 44 How Surge Protectors Work * 45 How Emergency Power Systems Work * 46 How Batteries Work * 47 How Power Distribution Grids Work * 48 Why are my power bills so high? |