Should I use a UPS on my laser printer?
A UPS's main job is to provide back-up power in order to save volatile data. In the case of a laser printer, print jobs are readily re-queued, so there is no real loss of data should a power outage occur while printing. APC SurgeArrest is a cost-effective way to protect a laser printer. However, for a desktop publishing application in which a large amount of time is invested to download fonts, a UPS may be required.
What about the PC workstations on the LAN?
According to Novell, We strongly recommend that you use UPS protection for network workstations. Protecting network workstations has always been a necessity; however, until the introduction of APC's Back-UPS, a cost-effective way to achieve these benefits was simply not available. Now users who are interested in protecting their LAN workstations can benefit from: Since the most recent work on a file may be performed on a workstation, client PC protection prevents data files corrupted on the workstations from being written back to the server. For this reason alone, UPS protection on workstations is recommended.
Can surges occur on phone and data lines?
Definitely. These backdoor non-AC events can be deadly to your hardware. Serial RS-232 interface ports on computers, terminals, printers, plotters and modems are especially sensitive to damage from electrical transients because they use the computer chassis ground as a signal common. Protect both ends of an RS-232 serial cable longer than 5 feet (1.5 m). Protect the 25 or 9 pin port of your computer or terminal with an APC ProtectNet model PS25-DTE or PS9-DTE. Protect the 25 or 9 pin port of your modem, printer and plotter with an APC ProtectNet model PS25-DCE or PS9-DCE. Do not attempt to run RS-232 links between equipment in separate buildings - use quality short haul modems for this purpose.

Protect your Ethernet Network Interface Cards and other LAN equipment at each end of your networks 10Base-T UTP, or coaxial Thinnet cable. Thinnet (10Base-2) networks are especially susceptible to intersystem ground noise when the cable shields are inadvertently grounded at more than one location. Verify your system's true single ground point and check to be sure that T connectors or any exposed connector barrels are not touching the metal chassis of your computer.

Protect your 4 and 16 Mbps Token Ring Network Interface Cards and other LAN equipment at each end of your networks UTP cable.

Protect the telephone port of your modem, fax, telex, answering machine, etc. from damage due to nearby lightning activity with an APC ProtectNet model PTel2 or SurgeArrest with telephone protection. Protect each telephone line wire pair.

Finally, protect the RF video input of your television or your computer's TV board with an APC SurgeArrest with CATV surge suppression.
It's not necessary to protect modern keyboards. Computer monitors require no video cable protection when the monitor is plugged into the same utility service branch as the computer.

What about output waveform?

A UPS's output waveform must deliver proper peak and RMS (a kind of average power) to the load. Ideally, this is accomplished with a sine wave identical to AC power, although a step sine wave can be designed to provide both proper peak and RMS values.

Square wave output UPSs, in contrast, deliver output with peak power identical to RMS power. This creates stress on components, premature failure, and hence, decreased reliability. Only purchase UPSs with sine wave or stepped wave output.

(Top) Ideal sine wave power (under load) from APC Matrix or Smart-UPS, (middle) stepped wave power from APC Back-UPS, and (bottom) undesirable square wave output from a competitive brand, which fails to provide proper peak and RMS values to your computer.

A salesman is trying to get me to pay more for on-line protection? Should I do it?
Of the three general types of UPS protection (on-line, standby, line-interactive), on-line is the oldest. If reliability is a concern, your choice should be line-interactive or standby. In fact, a study titled AC-UPS Reliability and Availability Performance: Comparison of Available Solutions presented by independent researchers Mssrs Sunito, Uusitalo, and Jonsson at the 1989 INTELLEC conference showed that from a computer users standpoint all popular UPS solutions were equal in performance but that using standby UPS or line-interactive systems reduced downtime more than twice as much as using an on-line. In addition, the Mean Time Between Failures (MTBF) over a 10 year period for a standby UPS and line-interactive UPS was twice that of an on-line.

A study by PC magazine showed that on-line market share dropped precipitously (12%) over the last few years, while line-interactive (which APC invented) has grown strongly. At the same time, a recent article in PCweek, warned users to demand schematics whenever pressured to purchase an on-line UPS, as many so-called on-line UPSs incorporate switches and are on-line in name only.

What do new PFC computers mean to my UPS choices?
Modern computers incorporate a Switched-Mode Power Supply (SMPS) for converting AC to the DC required by the computer. Newer versions include power factor correction. While PFC eliminates dangerous harmonic currents, it is incompatible with some UPS designs, most notably ferroresonant based UPSs.

Federal standard, FIPS PUB 94, entitled Guideline on Electrical Power for Automatic Data Processing Installations addresses the ferro's potential system instabilities. Lab tests have also shown:

While currently small, the number of PFC-equipped computers is expected to grow very rapidly as new legislation takes effect and computer manufacturers release new models incorporating PFC power supplies.
Surge suppressors are all the same. If it's UL listed I'sm OK, right?
UL-listed means a product has been submitted to Underwriter's Labs for safety testing in a certain product category. However, the surge suppressor you paid $4.99 for may be UL-listed in the extension cord category.

The UL listing for surge suppressors is UL 1449. APC's SurgeArrest products are the lowest priced surge suppressors to receive the best UL 1449 rating of 330V across all lines. Keep in mind that some vendors rate surge protection on the basis of joule energy. The IEEE specifically warns that such ratings are misleading. Instead, the IEEE surge Let-Through measure should be compared.

Do I need to protect my laptop?
While laptop computers spend a large part of their time disconnected from power problems happening at the outlet, they are highly susceptible to surges traveling along serial and modem lines right into the CPU. If you have an internal modem, you should protect this investment with an appropriate data line surge suppressor.
Myths & Misconceptions Perhaps the biggest myth (propagated by UPS manufacturers that will try to sell you more than you need for more than you should pay) is that so-called on-line or no-break are the only units appropriate for fileservers. In fact, both independent editors and third party vendors have endorsed standby and line-interactive designs for their equipment for one simple reason: far greater reliability.
--Compaq Computer

--IBM Corp.

--PCWeek 5/91

--PC Magazine 11/90