Some folk like to run their sensitive equipment though their uninterrupted power supply system, even when the grid is on line. This makes a deal of sense in areas where utility power is intermittent, for example after a severe storm. They may gradually add more items for convenience without considering their online UPS capacity, and then wonder why it stops working properly.
The Budget Analogy for UPS Capacity
We just love this analogy we stumbled over on The Economist website. They cite an example of a government that overspends its budget to keep the electorate happy. It then has to dip into its reserves to balance the books, and eventually has to raise taxes.
Many folk hit their credit cards hard over Thanksgiving and Christmas, and then battle for the next couple months. That’s because their income-earning capacity is limited, just like an online UPS battery. If you take more energy out of it than you are putting in, eventually that battery is going to run flat.
A hydro power system is like a giant battery too, and serves as another analogy for battery capacity. The system releases water downhill, where gravity feeds it though a turbine to make electricity. However, the operator has to regularly pump the water back to the upper supply dam, or else it will steadily empty.
An Online UPS System Works the Same Way
We heard of a case where a fellow used his swimming pool to successfully fight a small bush fire. He kept topping it up with low-pressure water from the utility while he was doing so. However by the time the fire was out, the pool was almost empty.
An online UPS is supposed to top up its battery as the user draws the electricity to power a load. This system works fine, as long as an external power system is available, and the amount of the draw does not exceed the amount the UPS system can process.
However, the total load may exceed the UPS capacity, if that user adds an additional, high-demand device. The battery will drain down even though the utility supply is working perfectly, and eventually run flat. Avoid draining batteries flat this way, because it can damage them permanently.
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Online Or Offline UPS: Let’s Compare
