Rosewill Computer Case 422 Technical Information PDF herunterladen (Seite 73)

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Chapter 4 • Disassembly and Power

Figure 4.31 Surge protector

Most surge protectors have an electronic component called an MOV (metal oxide varistor),

which protects the computer or device that plugs into one of the outlets on the surge strip. An

MOV is positioned between the AC coming in and the outlet into which devices are plugged.

When a surge occurs, the MOV prevents the extra volt-

age from passing to the outlets. An MOV, however,

has some drawbacks. If a large surge occurs, the MOV

will take the hit and be destroyed, which is better than

damaging the computer. However, with small overvol-

tages, each small surge weakens the MOV. A weakened

MOV might not give the proper protection to the com-

puter in the event of a bigger surge. Also, there is no

simple check for an MOV’s condition. Some MOVs have

indicator lamps attached, but they indicate only when the MOV has been destroyed, not when

it is weakened. Still, having an indicator lamp is better than nothing at all. Some surge pro-

tectors also have replaceable fuses and/or indicator lamps for the fuse. A fuse works only once

and then is destroyed during a surge in order to protect devices plugged into surge protector

outlets.

Several surge protector features deserve consideration. Table 4.8 outlines some of them.

Table 4.8 Surge protector features

Feature Explanation

Clamping voltage

The level at which surge protector starts protecting the

computer. The lower the value, the better the protection.

Clamping speed

How much time elapses before protection begins.

The lower the value, the better the protection. Surge

protectors cannot normally protect against power spikes

(overvoltages of short duration) because of their rated

clamping speed.

Do not create a trip hazard with a surge

strip

When installing a surge protector, do not install it in

such a manner that it causes a trip hazard because

the cord lies in an area where people walk.

Tech

Tip

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Rosewill Computer Case 422 Technical Information Seite 73