Tips for choosing "UPS" correctly-How to calculate capacity? What is the power supply method? : SOHO / How to choose "UPS" that works for SMEs (2nd) (1/3 page)

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How to choose UPS

The lineup of "uninterruptible power supply (UPS)" is divided mainly according to the capacity of the built-in battery. In short, we have different products depending on whether the power consumption of the connected device is high or low.

Actually, there are other factors such as the difference in power supply method and output waveform, but let's put off those differences for the time being and first take a quick look at the method of measuring the required capacity.

When selecting a UPS, first write down the power consumption of each device you want to connect to. There should be a description of power consumption (W, watt) on the manufacturer's website and product instruction manual, so make a note of it.

For example, if you create a list like the one on the left and save it in Microsoft Excel etc., it will be easier to recalculate even if the device is replaced in the future, and the person in charge of device management at the corporation will be handed over to someone. It's also easy.

By the way, in the past, it was common to calculate using not only power consumption (W) but also apparent power (VA, volt-ampere), but the manufacturer's website and product instruction manuals use power consumption (W). ) Is written more reliably, so it is easier to calculate based on that. If apparent power (VA) is required, it is advisable to use the value obtained by dividing the power consumption (W) by 0.6.

For power consumption, there are cases where two types of values ​​are displayed, such as "60W at maximum configuration and 20W at normal time" on PCs. In this case, it is correct to calculate with the maximum value. Also, devices added later, such as desktop PC graphics cards, may consume a considerable amount of power, so be sure to add them.

In addition to this, as the battery deteriorates, the performance drops to about half, so it is ideal to calculate with "maximum value x 2" in consideration of that, but doing so would be too expensive. You can calculate it by adding 20% ​​at most, and then replace it as soon as it reaches the end of its life.

In other words, if the total power consumption of the equipment is 300W, you should look at about 360W at 1.2 times. This is the reason why it is often stated in the selection method of UPS that "it should be seen about 1.2 to 1.3 times the calculated capacity".

Find the perfect UPS with the calculation tool provided by the manufacturer

Now, once the total power consumption has been calculated, determine the time to drive the connected device. For example, you may say, "It only takes 3 minutes because it just shuts down safely," or "It takes 1 hour because you can't stop the work even if there is a power outage due to equipment inspection." The price range of the product is completely different between the former and the latter, but for the time being, decide on a guideline time.

Once these two data are available, it will be possible to find a suitable model by comparing it with the battery capacity of the UPS.

However, once these two data are available, it is difficult to find a product that meets the conditions on the manufacturer's website or catalog. Many people may be worried whether the calculation is correct.

A calculation tool provided by UPS manufacturers on their websites is useful in such cases. If you use this, you can easily find a UPS that matches the conditions by inputting the total power consumption and backup time.

For example, Schneider Electric, which sells UPS under the APC brand, offers a calculation tool called "UPS selection support" at the online shop "Shop APC". Similarly, OMRON has a page called "UPS Selection Tool" on its own site, which can be easily used. The voltage should be calculated at 100V (volt).