78
Active Eco-Mode provides a degree
of bypass power conditioning as
well.
The Active Eco-Mode approach
(Figure 6) eliminates prior eco-
mode issues by keeping the inverter
and rectifier in an active state.
Because the inverter is kept in an
active state, and is providing an
output that matches the bypass, it is
ready to accept the load instantly.
As a result, the transfer to the
inverter can be accomplished
almost seamlessly.
Figure 6. Double conversion operation, active
inverter eco-mode and conventional eco-mode
configurations.
Keeping the inverter in a constant
state of preparedness does require
additional power; however, the
power requirement is below 1
percent of the UPS rated power,
creating potential savings of 4 to
4.5 percent compared with typical
double-conversion operating
modes. The result is a more
continuous output wave form, a
more seamless transfer and possible
UPS efficiency levels above 98
percent. Also, keeping the rectifier
in an active state ensures a constant
float charge across the UPS battery,
which is shown to have a significant
positive impact on battery life.
InTellIGenT
PARAllelInG
Another newer function enabled by
UPS controls is intelligent
paralleling (Figure 7), which
improves the efficiency of
redundant UPS systems by
deactivating UPS modules that are
not required to support the load
and taking advantage of the
inherent efficiency improvement
available at higher loads.
For example, a redundant multi-
module UPS system configured to
support a 500 kVA load using three
250 kVA UPS modules can support
loads below 250 kVA with only two
modules, while maintaining
redundancy and improving the
efficiency of the remaining on-line
UPS modules by enabling them to
operate at a higher load levels.
This feature is particularly useful
for data centers that experience
extended periods of low demand,
such as a corporate data center
operating at low capacity on
weekends and holidays.
SUMMARy
As the complexity of data center
environments continues to grow,
data center managers are
increasingly concerned about
maintaining or improving
availability in increasingly dense
computing environments while
increasing efficiency and reducing
costs. Therefore, it is important
they pick the right flexible UPS
technology for their data center.
Historically, data center designers
and managers have had to balance
tradeoffs between availability and
efficiency in the data center power
system. Online double-conversion
UPS modules provided the highest
availability but could not deliver the
same efficiency as a line-interactive
topology.
Advances in double-conversion
UPS technology have closed the
gap in efficiency, and new features
have been introduced that enable
double-conversion UPS systems to
achieve efficiencies on par with
line-interactive systems while still
providing the needed power quality.
These technology advances and
new features help organizations
safeguard availability while
increasing efficiency and advancing
scalability in the data center.
7X24 MAGAZINE FALL 2014
Peter Panfil is VP of Global Power at Emerson Network Power. He can reached at
Figure 7. Intelligent paralleling of UPS modules.
