White Paper

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6. Intelligent control of critical power
UPS systems now include digital controls
with the intelligence to alter and optimize
the performance of the UPS. They
automatically calibrate the system and
ensure the UPS is working properly. In
addition, they ensure that the UPS switches
between traditional operation and bypass
during overloads, protecting the UPS
system and the overall power infrastructure.
This minimizes the need to make manual
adjustments based on site conditions.
Instead of requiring a service technician to
manually adjust the analog controls, the
UPS system itself monitors the conditions
at the site (power factor, load and ambient
temperature) and makes adjustments to
maintain optimum performance.
These controls also enable more efcient
operation through energy optimization
and intelligent paralleling features.
Energy optimization mode increases UPS
efciency by powering the IT load from the
bypass path while providing some power
conditioning. An organization may choose to
activate energy optimization during periods
when utility power quality is thought to
be particularly good or when availability
requirements are not as high, such as nights
or weekends. Energy optimization mode
can improve UPS efciency by as much as
ve percentage points, but also introduces
the possibility of compromising total power
protection. This risk can be mitigated when
the controls are designed to keep the UPS
inverter “hot” while the system is in energy
optimization mode, allowing faster response
to utility power disturbances.
Intelligent paralleling provides another
option for improving UPS efciency in multi-
module systems. Intelligent paralleling
manages the load across multiple UPS
modules and can automatically deactivate
modules that are not required to support
the load, while still ensuring that the system
is providing adequate redundancy. For
example, a four-module N + 1 system sized
to support 700 kVA using four 250 kVA UPS
modules can support loads below 400 kVA
with only three modules. This capability
can improve system efciency by up to six
percent without sacricing protection.
Centralized Monitoring and
Management
Current generation power and cooling
systems feature sophisticated displays
that provide a wealth of operating data.
The Liebert CRV cooling system, for
example, can show trending of server inlet
temperatures for multiple racks. But in
the dynamic, every-second-counts world
of the data center, local management
of infrastructure systems is typically
inadequate to meet high efciency and
availability requirements. That has spurred
the use of centralized monitoring systems.
Centralized monitoring systems are available
today that operate across the existing IT
network or across a dedicated network.
Sites smaller than 2,500 square feet
generally choose to use the existing network
rather than set up a separate network,
while larger facilities will benet from a
dedicated network that provides the ability
to integrate with building automation and
management systems and manage multiple
facilities.