Overview

This chapter provides guidance on creating a complete system. Although not exhaustive it will give guidance and illustrate areas where problems may be envisaged.

The quintessential question is system power rating. It is surprising how hindsight illustrates how easily errors occur in this area. For example, the usage of computer systems inevitably grows with time, and often it is difficult for the exact rating to be determined. Here are a few points which need examination: The existing computer has every chance of expansion, but by how much and over what time period. Is it feasible that the computer may be reduced in size and much of its work is delegated to peripheral computer centers?

The possibility of adding further power blocks at a later stage, and thus paralleling UPS units and prime movers will have to be considered, it should be noted that if this decision is preferred the eventual system cost will be increased.

Although we have considered computers, the same considerations should also apply to other loads. Lighting has its own particular aspects requiring attention. Discharge lamps do have fairly high starting currents, and some discharge lamp circuits will necessitate consideration of waveform effect on the UPS and, indeed, the generator. It should also be remembered that even the mundane Tungsten lamp has a starting surge of approximately 12 to 15 times normal run current, and halogen lamps approximately 20 times normal run current. These starting surges are transient, lasting no longer than approximately 5 to 10...