Powerware Power Protection Handbook for IBM 9910 International System i and System p Applications
12
How Much Battery Runtime Do You Need?
To meet customer needs of continued operation during power outages, Powerware 9910 UPS solutions
offer options that can extend battery runtimes beyond 60 minutes. In today's 24x7 business environment,
continued availability along with application and safety considerations must be taken into account and
estimated when calculating UPS battery runtimes.
For example, a typical battery runtime is 15 minutes. The recommended formula used to calculate runtime
is: Runtime (calculated in minutes) = business + system application shutdown + safety
Example
Business needs = 5
System (application) shutdown = 6
Safety margin = 4
Total battery runtime required = 15
Business needs: Approximately 80% of power outages are less than 5 minutes in duration. Using 5
minutes will ensure that if the typical power outage is less than 5 minutes, the application will not start a
premature or unrecoverable shutdown. In the example, 5 minutes is used.
System shutdown: The National Power Laboratory (1990-1995) Power Quality Report indicates there
may be consecutive power outages before power continuity is fully restored. By doubling the
system/application time, you allow for two consecutive power outages to occur while providing an
adequate reserve of battery runtime to initiate a safe system shutdown during the second power outage.
In the example, it takes the application 3 minutes to shut down. Doubling the shutdown time results in 6
minutes.
Safety margin: Allows for natural battery charge cycles, temperature variations and aging. Also take into
account variations in business needs. In the example, 4 minutes is used.
Find the correct UPS model then select the runtime required. If the power consumption of the equipment
to be protected is unknown, use the maximum load (Watts) number given for the UPS.
For example, if the load requires less than 2,100 Watts and the runtime is 15 minutes, a valid UPS will be
the E30 with one Extended Battery Module providing 25 minutes of battery backup (autonomy) runtime at
the E30 maximum capacity of 2,100 watts.
Note: The runtime is total (standard internal batteries and optional EBMs), not additive.
Battery Runtime in Minutes
UPS
Model
Maximum
Watts
Supported
Standard
(Internal)
Battery +1 EBM +2 EBMs +3 EBMs +4 EBMs
EBM
Feature
Code
P14 950 5 - - - - None
P16 1050 8 37 70 106 144 6605
E30 2100 5 25 38 54 70 6644
E33 2700 5 25 49 69 90 6643
E64 4200 10 30 52 76 102 6645
E65 4500 7 24 46 67 89 6645
E82 8000 5 12 27 36 45 6646
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