Uninterruptible power supply (UPS) systems are critical components of a cohesive power reliability program. But just because a UPS is running does not mean that it is fully operational or that it can fully protect your system. UPS systems have technical limitations in resolving potential power quality issues. Just as important, any individual UPS system may not be operating efficiently. If that UPS belongs to you, your operations can be in danger without you even knowing about it.
The limits of UPS systems
You invested in a UPS to keep your equipment and operations running. You may believe you are immune to the impacts of power quality problems, but your UPS may not be protecting you adequately because of two key factors:
* UPS systems are technically limited in their ability to mitigate power quality phenomena. Generally, UPS systems cannot resolve high-ground current, inductive noise, system harmonics, phase imbalance, low-power factor, or susceptibility to lightning or RFI/EMI. Additionally, if the UPS bypass source is a generator, other problems may surface, such as frequency stability under load variations and higher-source impedance.
* Ensuring optimal operation of the UPS system is critical. Of particular importance is anticipating performance degradations before they become catastrophic failures.
Powerful information
The Signature System UPS Performance Verification Package from Dranetz BI delivers the information needed to ensure protection. By monitoring the broad spectrum of power quality phenomena, the Signature System provides answers to key performance questions:
* Is my UPS doing its job? The Signature System monitors the full range of power quality phenomena, from microsecond impulsive transients to sustained interruptions and interharmonics. A UPS unit's internal meters generally lack the bandwidth, sampling rate or trigger/capture algorithms to perform these functions.
* Is my UPS delivering clean power output - even if the quality of the electricity supply is compromised? The Signature System's unique cross-triggering capabilities, coupled with time synchronisation down to the sub-cycle level, allow for accurate and precise determination of its ability to provide clean power output. The UPS Verification AnswerModule compares the input to the output of the UPS, determining its effectiveness rating and power efficiency. This indicates clearly any disturbance that the UPS is unable to mitigate.
* Is my UPS causing any harmonic pollution to the supply side power? The AC-DC converters, typically integrated in the front end of a UPS unit, can be sources of harmonic currents if they are not adequately filtered, potentially affecting upstream equipment. The system provides information about conditions on the electric supply that are masked by the UPS. If those conditions remain 'hidden,' they can degrade beyond the ability of the UPS to correct.
Investment in a UPS can be a substantial expense for any company. The addition of a verification package is a small, incremental cost of the UPS system and only a small fraction of the cost of facility downtime.
For more information contact Darko Stanisavljevic, Spescom MeasureGraph, +27 (0)11 266 1536, dstanisavljevic@za.spescom.com
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