FOCUS on POWER
TOP OF RACK CONSIDERATIONS UPS MAINTENANCE
engineering resources during escalation
• Remote monitoring with monthly trended reporting, 7x24 alarm notification and rapid response linkage to field technician
• Adherence to recommended parts replacement cycles, especially items that wear out more quickly, such as batteries and capacitors
• Understanding of the UPS lifecycle, expansion features and total cost of ownership
• Access to 7x24 call center specialists and local technicians
• Maintaining accurate records
Since most batteries wear out every three to five years, it is critical that they are regularly inspected. And, considering the fact that the failure of a single battery jar can cause an entire UPS to fail, battery testing and replacement as needed are a fundamental component of a proper UPS maintenance plan, with most customers opting for semi- annual VRLA, or quarterly wet cell battery preventive maintenance.
A new trend in battery and UPS maintenance plans is to deploy a battery-monitoring system to constantly measure and report if any individual battery is out of factory specification. Load loss reports from customers who intended to self-monitor often reveal that the monitoring output was either not being viewed or had been misinterpreted. The load loss reports also show that many times there was not an effective process to link the bad battery alarm to a timely replacement.
A successful maintenance plan takes into account the age and actual wear of a UPS to determine where a specific device is relative to its expected lifespan. It also helps customers budget for major replacement items such as batteries or capacitors – items that customers may also choose to add into an appropriate maintenance agreement. A maintenance strategy should also include an understanding of where an organization is headed, as well as its priorities for continuous operations. For example, are systems lightly
Battery life Standby use – Three to five years for VRLA batteries; wet cell battery life is variable Cycle use – 1200 cycles at 30% of discharge; 550 cycles at 50% of discharge; 250 cycles at 100% of discharge Capacitors – Inspect annually. Replace every seven years or as needed
Hot-swappable Fans – Replaceable with unit online if redundant or on bypass. Verify annually, replace every seven years Lug terminals – Crimp and mechanical power lugs, annual visual and thermal inspection Air filters – Replace annually or as needed
COMMON UPS TESTS TO OPTIMIZE AVAILABILITY The most successful UPS installations, which are measured by system availability or uptime, include prescriptive maintenance programs that are rigorously enforced. Within an effective maintenance strategy are a number of functional tests and component checks that should be conducted regularly.
1. Transfer to bypass and return to UPS – This test checks the static switch and bypass breaker motor operator or contactor. The test interval should be at least annually and can be performed with the load on maintenance bypass.
2. Battery operation and return – Sometimes coupled with a transfer- to-generator support and return to
loaded? Is the business experiencing unusual growth? How resilient must your operation be and what do you consider a fast response? Is it the next day, the same day or in two hours? Once you have assessed your basic needs, you can prioritize which equipment requires maintenance agreements and what level of service is appropriate.
TYPICAL MAINTENANCE REPLACEMENT CYCLES The following guidelines will help you determine the optimal replacement period for various UPS components:
normal, this test is typically performed monthly and tests the UPS, generator and automatic transfer switch (ATS) functions.
3. Load balancing evaluation – This test checks for loads on any phase that may be approaching 100%. To limit potential overloads, loads may be redistributed as necessary. It is important to note that any one phase may be overloaded and trigger an unexpected alarm or transfer, even if the other two phases are only lightly loaded.
4. Phase rotation/site wiring checks – This test inspects for out-of-limit bypass alarms or site wiring faults that may have occurred as a result of normal site wiring changes or maintenance. These problems can go undetected until a transfer to bypass is attempted.
5. Listening tests – An experienced technician should listen for abnormal operational sounds, particularly arcing, fan-bearing noise or synchronization problems, including hunting sounds or beat frequencies. These subtle hints can easily go unnoticed by users unfamiliar with the warning sounds.
6. Operator refresher training – Since most power interruptions are a result of human error, constant attention should be paid to ensuring and documenting that all personnel with access to the UPS and associated switchgear have a solid understanding of the operation of the system and the consequences of any incorrect actions.
Every UPS contains life-limited components that must be replaced according to the manufacturer’s specifications. To ensure these parts are properly cared for and replaced when needed, regular maintenance is critical. An effective preventive maintenance strategy can be one of the most cost-effective measures you can take to ensure the ongoing health of both your critical equipment and your overall business. n
This is an excerpt from an Eaton Corporation white paper. To download the full white paper, visit www.powerware.com
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