Keeping that input voltage steady
By Red Squirrel
In telecom central offices, they have VRLA (may differ from place to place) ~2.5 volt battery cells. Usually in groups of 12 or 24. Usually the groups of 12 will produce 48V, but sometimes 24V (two 12 cell groups in parallel) and the groups of 12 will produce 24V. This is then fed to inverters and feeds the building as well as converts DC to AC if needed (depends on application). This UPS setup is the size of a room! These can keep the building up for quite a few hours.
For example, one of the central offices in my city produces over 150Amps of current with all the equipment. This is cisco routers, DE-4 channel banks, IMT150 switches, DMS x00 switches, and many other types of equipment.
But today, we won't go into giant batteries and giant inverters. A typical UPS for a computer is not very big, and runs on a single cell, it has an inverter (converts DC to AC) that can produce 120VAC for about 5 minutes. This is a picture of a UPS by APC:
What is great about a UPS is that your computer (or whatever you have plugged in) runs off the battery, and because the UPS is plugged in, it is always charging the battery. Just like the telecom facilities do it, but on a much smaller scale.
Because it is running on the battery, your computer will always get a constant flow of electricity. Any hits in the commercial AC will not affect your computer, because during the short period of time, the battery will still be supplying the right voltage.
A power supply has capacitors that work the same way (capacitors are like batteries, but last only a few seconds or less) but do not do a good job when it's large hits, as they cannot keep electricity for long. A UPS on the other hand will cover up mostly all surges and electrical hits. Also, a UPS will keep your computer running for you to shut it down in case of a power outage, that way you do not loose unsaved work. This also avoids the blue scandisk screen at startup because windows was improperly shut down.
A UPS will also protect your phone line from getting hit with a surge. You simply plug in the incoming line into the "in" and plug another line in "out" and into the equipment, such as your modem or phone.
The incoming line for the internet comes in the basement at my house, while my computer is upstairs, so in my case my line is not protected, but in general cases where the phone jack is where your computer is, you are protected.
In my situation, something that would not be a bad idea would be to get a phone line protector, this is a little box that plugs in the phone line and you plug the equipment in it, the same was as the jacks on the UPS. However, phone line surges are very unlikely, as the telecom company has their own UPS for this, but it's still possible.
On this particular UPS, there is another jack, this is similar to an Ethernet jack. The cable that comes with it has one end that plugs in the UPS, and one end that plugs into the computer's serial port. With the drivers installed, your computer will be able to communicate with the UPS and vise versa.
If you don't notice all the lights in the house go off during a power outage Ė the UPS will tell you: you got a power outage! The UPS also has beep codes for various situations such as overload, power outage, damaged or dead battery etc. To better understand what a UPS does, here is a graphical explanation:
AC current, also known as alternative current actually is a sine wave at a frequency of 60hz (some towns are 50hz, but rare). That's why in AC, there is no negative and positive. There is, but it switches wire per wire 60 times a second. It switches in a sine wave format, however, there is often ripples in the sine waves. The UPS will produce cleaner sine waves for the computer, using the power from the battery, which is always being charged by the comercial AC.
In conclusion, a UPS is a must if you want to keep your computer's electronic components healthy from power damage. I recommend that everyone has a UPS. However, it is still recommended that you unplug everything during an electrical storm. A UPS can take a few voltage differences no problem, but with lighting, we are talking of about 2000 million volts here! Donít take a chance!
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