FOCUS on POWER
complete mechanical revision on the full UPS and battery cabinets.
• Capacitors – A typical UPS contains a dozen or more electrolytic capacitors of different types and size, which smooth out and filter fluctuations in voltage. Like batteries, electrolytic capacitors degrade over time. While a typical capacitor might be rated by the manufacturer for five years of round-the-clock use, it could potentially deliver up to eight to ten years of useful life under favorable operating conditions. When a capacitor fails, there might not be any immediate visible effects, but other capacitors must compensate for the additional workload, which shortens their useful lives. In many cases, a capacitor failure will trigger the UPS to switch to bypass mode, at which time it is unable to protect downstream loads. Inspection of capacitors during preventive maintenance helps optimize their operation while also enhancing their lifespan.
• Air filters – Because dust may block air filters and cause a UPS to shut down due to overheating, they must be inspected every month. Replacing filters is an inexpensive component of an effective UPS maintenance plan.
• Power supplies – Although a UPS may have redundant power supplies, it is possible for the power supply to suffer from input voltage surges, which can cause unexpected stress and overheating. Regular inspection is recommended to detect potential issues.
Input filters – Currents, parameters and physical conditions of input filters need to be reviewed and inspected. The input filter helps to reduce total harmonic distortion (THD) from the UPS to the input line. However, depending on the amount of input line electrical noise, the filter may attempt to correct harmonic distortion for the entire installation, causing overheated cables and chokes.
• Contactors – Because they may collect fine dust and other resistive coatings, inspections and cleaning can prevent premature failures.
• Sticking or welded relays – These
Chart 1: The effect of routine maintenance on load loss events
may go unnoticed until emergency change-of-state events occur. Periodic inspections can detect potential problems before they occur.
• Motor operators – These should be checked for proper operation while disengaged from the breaker – a measure completed during a routine preventive maintenance visit.
• Firmware upgrades – Because upgrades incorporate the latest operational enhancements, they should be completed to ensure compatibility with new load devices, and to guarantee that the UPS is performing at optimum levels. A technician can complete these upgrades during routine service.
• Transient voltage surge suppression (TVSS) integrity – It is important to verify that metal oxide varistor (MOV) devices are functional and have not been compromised by excessive transients.
OVERCOMING FAILURES As Chart 1 illustrates, routine preventive maintenance significantly reduces the probability of a load loss event. Through the completion of systematic inspections, a preventive maintenance plan ensures that the various electronic and mechanical components of a UPS are thoroughly evaluated, cleaned, tested and calibrated on a regular basis. Without proper maintenance, many UPSs will fail prematurely, since critical components such as batteries and capacitors wear out from normal use. A
solid maintenance plan identifies issues and greatly reduces this risk of failure.
With an effective preventive maintenance plan, your business will have access to more reliable, higher quality and more cost- effective power – all of which minimize the risks of downtime and disruption to your business. Preventive maintenance is crucial in order to achieve optimal performance from your equipment.
Systematic inspections, testing and cleaning by trained technicians ensure that the various electronic and mechanical components of a UPS are functioning to their maximum potential. When problems are detected and repaired before they evolve into significant – and often costly – issues, your UPS is able to deliver the level of performance you expect.
AN EFFECTIVE PREVENTIVE MAINTENANCE PLAN There are a number of measures that are recommended to ensure the ongoing integrity of your UPS, including:
• Annual scheduled preventive maintenance for both the electronics and battery
• Access to rapid emergency response from trained technicians on the specific UPS models
• On-site parts inventory or local field technicians with van-stocked required parts • Access to technical support and design
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