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Straight talk about capacitors in your UPS

Straight talk about capacitors in your UPS
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Straight talk about capacitors in your UPS - 1

Manager, Eaton What they are, what they do, why they're essential in your UPS — and the importance of proactive maintenance for these humble and often overlooked components. Powering Business Worldwide Executive summary Capacitors are fairly simple devices, ranging in size from a thimble to a soda can, that smooth out fluctuations in electrical voltage. A typical UPS contains a dozen or more different types and sizes of capacitors — small ones that smooth out the power supplied to the UPS processor (its on- board intelligence), and large ones to regulate the power that flows to protected equipment. Like batteries, capacitors degrade over time. A typical capacitor might be rated by the manufacturer for, say, seven years of round-the-clock use, but could potentially deliver up to 10 years of useful life under favorable operating conditions. When a capacitor fails, you might not see any visible effects, but other capacitors will have to take over the workload, which will shorten their useful lives. In many cases, a capacitor failure triggers the UPS to switch to bypass mode, during which it can't protect downstream loads. To maximize the performance and reliability of your UPS, treat capacitors as the perishable commodity they are, and plan on replacing them at or near the end of their rated service life. Eaton® customer service engineers can diagnose the condition of the capacitors in UPSs and perform a full or partial replacement of capacitor banks, if necessary, to maintain UPS performance up to factory specifications. Proactive attention to this often-overlooked element of UPS architecture — the humble capacitor — can extend the value of the UPS system that protects your critical electronic systems.

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Straight talk about capacitors in your UPS - 2

6. How long do capacitors usually last? A capacitor is a fairly simple electrical device that stores and releases electrical energy. These devices can be as small as your thumbnail or as large as a soda can — depending on the amount of voltage they’re expected to digest (their rated capacity). Generally encased in aluminum or chromium-plated cylinders, capacitors contain a pair of conducting surfaces (often metallic plates or electrodes) which are separated and insulated by a third element, called the dielectric medium. The theoretical operational lifetime of a capacitor is a mathematical...

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Straight talk about capacitors in your UPS - 3

7. hat conditions influence capacitor longevity? W As lifespan is a function of rated voltage and operating temperature, it logically follows that you can shorten the useful life of a capacitor by overstepping its design thresholds in either of those areas. For example: • Excessive current – Capacitors can be destroyed if they are regularly exposed to over-current conditions, such as steady current that exceeds the manufacturer’s rating. Short periods of excessive ripple current are relatively harmless, as long as the capacitor doesn’t have to overheat to compensate. • Over-work –...

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Straight talk about capacitors in your UPS - 4

Conclusion To maximize the performance and reliability of your UPS, treat capacitors as the perishable commodity that they are, and plan on replacing them at or near the end of their rated service life. Be wary of choosing a third-party service organization over a UPS manufacturers certified technicians to replace capacitors. If the manufacturing company designs, engineers and manufactures your UPS, they will know it better than anyone else, and the technicians are specialists. Technicians should be trained, certified and will likely have access to proprietary diagnostic software and the...

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