30 UPS BATTERIES
Damage from a blown capacitor.
www.upspower.co.uk
Batteries: the importance of matching UPS quality with an equally good service plan
How good is your UPS? This overview from UPS Ltd, part of the Kohler Company’s Power Group, considers mission-critical UPS and the risks posed to revenue-generation activity which could be halted by a power failure. Today’s IT resource and data centre managers have to be assured that their UPS investment will continue to provide clean and uninterrupted power to protect and extend the life of the site’s essential equipment.
W
hile most users take extreme care in
selecting a suitable UPS system, the importance of matching the UPS quality with an equally well-qualified service plan is not always recognised. This is surprising, as the service plan is vital; if correctly run, it will keep the purchased UPS system running safely and reliably for 15 years or more, while UPS stoppages for many reasons will inevitably occur in its absence. The UPS battery, while being the heart of the system, is also a significant vulnerability, with typically 20% of UPS failures being attributed to bad batteries. Excessive tempera- ture variations and cumulative charge-discharge cycles
“The UPS battery, while being the heart of the system, is also a significant vulnerability, with typically 20% of UPS failures being attributed to bad batteries.”
shorten UPS battery life; this can be especially disappointing for buyers who have relied on UPS manufacturers’ battery life estimates based on ideal conditions of 20°C tempera- tures and no working cycles. In fact, battery life is typically
reduced by 50% for every 10°C increase in operational temperature. Additionally, a UPS battery which would withstand 1200 discharge cycles at typically 30% of discharge depth will last for just 250 cycles at typically
Worldwide Independent Power November 2017
100% discharge depth. An intelligent UPS service plan can mitigate these problems in many ways. The UPS system can run a battery self-test every 30-60 days, backed by an expert UPS engineer-conducted test every six months. Batteries should be renewed at 80% of their theoretical working life limit, while both battery monitoring systems and impedance testing should be deployed. Capacitors and fans
constitute other common failure causes. UPSs contain electrolytic capacitors which, like batteries, degrade over time, depending on electrical and thermal stress. Ageing capacitors can reduce performance, with leakage and swelling of the casing. A key capacitor failure can often drive a UPS system into Bypass
mode. Bypass switching can also be triggered by failures in fans, which are key guardians against overheating. Fan life- time depends on electrical and mechanical qualities and specifications. Failures in these components can be pre-empted through visual inspection during preventative maintenance, and maximising MTBF by replacing capacitors every 5-9 years, and fans every 3-4 years and again after 7-9 years. Other failure causes include
blocked air filters, incorrect input filter design and dirt in contactors. Elements of an effective UPS service plan include an annual preventative maintenance schedule for both UPS and batteries, together with access to a rapid emergency response from trained UPS engineers.
www.gmp.uk.com
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