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PCs, LANs and electrical power (or, how to leash power before it gets to your computer).

When we talk about the power of PCs and LANs, we usually mean what they can do for us -- not what it takes to run them, or the business consequences of problems related to electrical power. But, failure to anticipate power problems can be catastrophic -- potentially far more devastating, in fact, than telecommunications outages or attacks by software viruses.

Power problems can take a variety of forms. Spikes and surges are very brief blasts of higher voltage. Noise is a harmless but potentially disruptive irregularity in the sine-wave shape of normal alternating current. A brown-out is a drop in the power level that lasts several seconds or more. During an outage, power is entirely unavailable for anywhere from seconds to days.

Power problems can be caused by such things as lightning strikes or utility blackouts. They also can be caused by everyday events like the freight elevator's mid-day trip, or by current-drawing components starting or stopping in air conditioners, copy machines and other office equipment.

Depending on how your office's electrical circuits are set up, and whether you have power protection, any one of these events can wreak havoc with your work in process, stored files, and even your equipment. The time you spend restoring your systems is time that you're not working.

For example, even a small change in electrical power can affect the contents of your computer's RAM, where documents, spreadsheets and databases are stored. A few garbled sentences in a document easily can be fixed, but restoring the integrity of a database is much more difficult and time-consuming. If a minor power surge or spike hits your computer's program image in RAM, your system may hang or crash. While you typically will be able to reboot, you may have lost vital work or information.

A large power surge or spike can have more serious consequences. It can scramble parts of data and program files on your hard disks, or cause physical components such as delicate integrated circuit chips to wear out faster.

A powerful enough surge can rocket through your systems, arcing across air gaps between closely spaced conductors inside chips, and literally melt anything from circuit boards to plastic casing, exploding monitor screens and starting fires.

Devices called surge protectors or surge suppressors can be used to block out power spikes. Most power protection equipment uses tiny components called metal-oxide varistors (MOVs). MOVs wear out over time, yet few surge protectors alert you to this condition so that you can replace the device. The best advice: beware -- you may not be as safe as you think you are!

Moreover, when MOVs divert surges away from computer power supplies, it's possible for the power surge to rush into data lines such as local area network (LAN) connections or modem wiring. This causes more damage than if you had no power protection at all.

Surge protectors can cost anywhere from $10-$250. Devices that don't use MOVs are more expensive, typically beginning at $150, but are more reliable.

BACK-UP POWER

Loss of power can be as damaging to your work as spikes or surges, although less physically hazardous to your equipment. While most of today's systems can tolerate as much as a half-second of power loss, longer interruptions can scramble or lose the contents of non-volatile RAM. In cases where a computer is acting as file server for many users on a LAN, they may all lose critical information, and be prevented from working.

To provide hack-up power for file servers, LAN equipment and other priority components, get either a stand-by power supply (SPS) or an uninterruptible power supply (UPS) for each. Each type of device has a battery, which stays charged from the wall current. An SPS switches over to its battery when regular power fails. A UPS, also called an on-line supply, always provides power through its battery.

A UPS is not necessarily better than an SPS. The power it delivers may be less "healthy" and wear out components faster. Also, it is often noisier, generates heat, and raises your electric bill.

SPSs and UPSs for PCs and LAN servers are available from $150 to $1,000. Make your choice based on how much power your essential equipment requires, and how long you need to maintain power in order to shut down or keep working.

When connecting your power protection, follow these steps:

* First, plug only PCs, monitors, servers and network devices into your SPSs or UPSs.

* Second, plug the SPSs or UPSs, along with printers and less critical components, in the surge protector.

* Third, plug the surge protector into the wall outlet.

At minimum, surge-protect all devices, and ensure back-up power for your file servers. Do not use ordinary surge protectors in LANs or with modems: because the surge may go to the ground used by all data lines, these devices increase the risk of surge damage. If you're running "non-stop" applications such as medical, finance and reservation systems, reserve power for user stations will also be helpful. Even home-based PC users need at least a surge protector.

Different areas of the country experience different levels and frequencies of power problems, but you can count on matters getting worse, not better. Do the smart thing and avoid putting your business' most valuable and hard-to-replace asset at risk.

Power Planning Checklist

These tips will help you ensure safe, reliable power for your computers and networks.

* Get expert advice about power wiring, especially if you have LANs. Make sure everything is grounded properly.

* Consider optical isolation connectors for your LANs and other data circuits.

* Make sure users cannot casually turn off power to essential LAN servers or other network devices.

* Do regular full and incremental backups to off-side storage.

* Test your SPS periodically (by pulling its plug) as well as all surge protectors.

* Purchase insurance designed specifically for computer hardware and software. Typical cost: $12-$15 pe $1,000 of coverage.

* If you have to work during a thunderstorm, be sure you have non-MOV-based protection, Or, consider using a battery-powdered laptop computer.
COPYRIGHT 1993 Canadian Institute of Management
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1993 Gale, Cengage Learning. All rights reserved.

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Title Annotation:personal computers; local area networks
Author:Luczak, Mark
Publication:Canadian Manager
Date:Jun 22, 1993
Words:1005
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