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Back Up, Restore & Protect Data April 2003 • Vol.9 Issue 4 Page(s) 136-138 in print issue |
More Power To You Surge Protectors Halt Dangerous Voltage Fluctuations | ||
 Most people know that a surge protector is one of the most important pieces of equipment you can buy for your PC. What many people do not realize, however, is that different surge protectors provide different types or levels of protection for your computer. We will take a look at the basics of electrical surges, spikes, and sags, as well as the different types of surge protectors.  When Electricity Is Unstable. Although we think of surges in electrical current as devastating, the truth is that there are normal fluctuations in the amount of electricity that flows through your home's outlets every day. Most of these fluctuations are minor and harmless, while others may be severe enough that they damage your computer and other electronic equipment. Just how do such fluctuations attack your PC? You can think of a power surge as a sudden increase in electrical pressure. The current, measured in amps, indicates the rate at which electricity moves. What causes the damage to an unprotected PC, however, is the electrical pressure, or voltage. For this reason, what determines the strength of a surge is a combination of the amount of power and its velocity. When a large amount of power suddenly moves very quickly, there will be a jump in the voltage, or electrical pressure. In the United States, most equipment and outlets are designed for 120V (volts). When the voltage rises above 120V, it creates a power spike or surge. When it drops to less than 120V, there is a power sag. Although not as highly publicized as surges and spikes, power sags can also be devastating. The difference between surges and spikes is somewhat ambiguous, but generally a spike is an extremely short fluctuation, while a surge lasts longer, usually at least 3 billionths of a second. Unless very strong, a spike is generally less destructive than a surge because it does not tax your electrical devices for as long. It is a combination of the strength of these fluctuations in voltage and the duration of the fluctuation that cause the damage to PC components, such as its CPU. When voltage suddenly increases, the excess electrical force will strain your PC's components, either destroying them or shortening their lives.
Most people are aware that a surge can damage a PC, and many people buy surge protectors as insurance against lightning strikes. Ironically, however, surge protectors will not save a computer from very large lightning strikes that are close by. Such a devastating strike simply produces more voltage than a surge protector can handle. For this reason, if you are at home during a thunderstorm, you should unplug your computer rather than rely solely on a surge protector. A surge protector is still important, however, to protect against surges that occur in your home on a regular basis. For instance, when your refrigerator's motor kicks on, it suddenly demands an increase in electricity. This causes fluctuations in the voltage in your home's outlets. When dramatic enough, these everyday fluctuations can damage a PC. Other voltage fluctuations occur due to bad wiring in your home or failure of your electric company's equipment. A surge protector can provide protection from many of these less-than-lightning-bolt-level surges. How Surge Protectors Work. To understand how a basic surge protector works, we must first understand the basics of an electrical outlet and how it works with a power cord to power your computer. An electrical outlet has three slots, one for each of the prongs on a power cord, such as the one that powers your computer. The left slot on an outlet is the neutral slot. The right slot is hot, and the lower slot is the grounding slot. Power moves from hot to neutral, so when you plug a cord into an outlet, power flows from the hot plug into the hot socket to the neutral socket and back out to the neutral plug. This completes a circuit, just as attaching the positive and negative ends of a battery to the correct ends of a device conducts electricity. The grounding slot is rarely used. Its purpose is to divert potentially fatal electrical current. For instance, if a damaged component in an electrical device were to complete a dangerous circuit, the grounding wire would protect the user from a serious or possibly even fatal injury. Although the grounding socket is rarely used, it serves an important precautionary role.
Vacuum-tube technology. The first surge protectors incorporated vacuum tubes, selenium (which is a type of metal), and carbon blocks in their design. However, computers required a greater level of protection than these surge protectors could provide. The vacuum tubes simply could not respond to a surge fast enough to save a computer's sensitive components. MOV protectors were the answer to the problems with the older vacuum-tube technology. MOVs. MOV protectors use a series of tiny MOV disks to connect the hot wire to the grounding wire inside the surge protector. Each of the MOVs is a tiny, circular disk or plate that is made up of metal oxide. Two semiconductors, one on each side of the disk, connect it to the wires. One semiconductor attaches the metal-oxide disk to the hot wire, and the other semiconductor attaches the disk to the grounding wire. The philosophy behind this design is that the MOVs conduct electricity to a greater or lesser degree, depending upon the strength of the voltage. Because of this adaptability, MOVs are sometimes called varistors (variable resistors). When the voltage is at 120V (where it should be), the MOVs do nothing to adjust the electrical current. If the voltage drops below 120V, however, the MOVs create more resistance so the already limited voltage can't pass from the hot wire to the grounding wire. When the voltage increases, the MOVs lessen their resistance accordingly, letting the excess voltage pass from the hot wire to the grounding wire. Gas discharge arrestors. These surge protectors work in a similar manner as the MOV protectors, except a gas controls the flow of current between the hot and grounding wires rather than a pair of semiconductors. Depending upon the strength of voltage, the gas is either a less or more effective conductor of electricity. In this way, the gas, like the MOVs, controls whether current passes through the hot wire or whether some of the current is deflected to the grounding wire. These surge protection devices are not the type you would have in your home. It is more likely that gas discharge arrestors would protect the phone and data lines of a business than they would be used to protect a personal computer or other household electronics. Series-mode surge suppressors. These surge protectors use a completely different type of technology to handle power surges. Instead of directing excess voltage to the ground line (as MOVs and gas discharge arrestors do), series-mode surge suppressors absorb the excess voltage and then gradually let the current pass through the hot wire after the surge ends. The benefit of a series-circuit surge protector is that it doesn't deflect volt
For instance, if your MOV protector halts a major power surge, the electricity that runs back through the grounding wire could surge through a phone line. If this phone line is connected to your computer's modem, a power surge can still hit your PC even though the surge protector stopped the electricity from traveling through your computer's power cord. Series-mode surge suppressors are not prone to such risks. However, most people use MOVs because they are more affordable. The lowest priced MOV probably costs only one fourth as much as the lowest priced series-mode surge suppressor. Only you can decide if spending more than $75 for a series-mode surge protector is worth the added insurance the device provides. What To Look For In A Surge Protector. Speaking of the price of surge protectors, it is important to know what to look for in a surge protector so you can get the best value and the protector that best suits your needs. Your computer's power supply probably provides some protection against surges. However, it cannot protect you against larger surges, which is why you should still invest in a surge protector. We'll take a look at some of the things you should consider when selecting a surge protector. Is it a surge protector? This one might sound ridiculous, but not every device that looks like a surge protector really is. If you spend less than $20 for a surge protector, it is highly likely that what you really bought was a glorified extension cord: a power strip with additional outlets but no real protection from transient voltage. Check the device's box for a label or list of specifications that indicate the UL (Underwriters Laboratory) categorizes it as a transient voltage surge protector. UL code. While you're checking the UL's classification of the device, also check for UL Code 1449, which lets you know that the surge protector is safe to use in your home. If you don't see UL Code 1449 on the box, don't buy the surge protector. Protector light. One of the most important things to look for in a MOV surge protector is a protection-indicator light. Once hit with a particularly large surge, the MOVs may be destroyed, leaving them unable to protect your system from future surges and spikes. If your surge protector has an indicator light, you know when the light is burned out that the device was hit with a power surge and no longer functions well enough to protect your PC or other attached equipment. This is how you know it's time to replace your surge protector; when the light burns out, it's time to go shopping
Clamping level. Also known as the suppressed-voltage rating, the clamping level tells you the maximum voltage a surge protector will let your computer (or other attached equipment) reach. More expensive surge protectors will have a lower clamping level. You will have to weigh the benefits against the price. You should not buy a surge protector, however, that has a clamping level of more than 330V. Clamping response time. Compare surge protectors in your price range and look for the one with the lowest clamping response time. The quicker the clamping response time, or the time it takes for the surge protector to respond and halt a surge, the less damage your PC will likely incur. This is because the duration of excess voltage has an effect on the amount of harm a surge causes. A MOV surge protector will experience some delay in the time between when a surge strikes and when the protector responds. However, if you buy a series- mode surge suppressor, you do not need to worry about the clamping response time because series-mode surge suppressors respond to a surge immediately. How much difference the clamping response time makes is somewhat debatable, though; even a MOV protector responds in just thousandths of a second.
Which Surge Protector Is Right? Only you can determine which surge protector is right for you. Consider the value of your computer equipment. How old is the computer? How much would it cost to replace it? Think about how much protection you need on average. Do you live in an area that encounters many spring and summer thunderstorms? Do you trust the wiring in your home? Select a surge protector in the same way you would select car insurance or a health insurance plan. Weigh your probable risks and the costs you would incur if the worst happened against the cost of the surge protector. Find the surge protector you feel provides the best balance between price and protection. Which surge protector you should buy is something only you can answer. What isn't debatable, however, is that your computer needs some level of protection from power surges. With this article as a guide, you can pick the surge protector that is right for you.  by Kylee Dickey |
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