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measures are instituted to provide
an acceptable level of availability,
transformer-free technology may be
the optimal choice. In general, 200
kW is a threshold below which the
space, weight and cost advantages
of transformer-free UPS systems
outweigh the robustness and higher
capacity capabilities of transformer-
based systems.
CAPACITy-on-deMAnd
Some UPS technologies now enable
modularity within the UPS module
itself (vertical), providing capacity-
on-demand that enables data center
managers to meet current capacity
requirements, while ensuring they
can easily and cost-effectively adapt
to future demands.
Certain UPS units in the market
provide capacity on demand by
using software to increase capacity
without adding to the system
footprint. UPS units with this sort
of software functionality can be
sized to current requirements and
then easily scaled up to a larger
capacity with a simple software key
as power needs change. These types
of modules are scalable in
increments, such as scalable from
40 to 80 kVA, from 80 to 120 kVA,
or from 160 to 200 kVA in 20 kW
increments.
Some row-based, modular UPS
units allow quick power capacity
increases with the addition of
internal power core hardware
assemblies. These core assemblies
allow the system to expand for
capacity or redundancy in 15 kW
increments up to 45 or 90kW
within a single cabinet. It is
important to look for power cores
that incorporate distributed
intelligence and scalable power in a
common assembly and allow
configuration of a completely
redundant power and control
system, sized to match the capacity
of the protected equipment. When
power requirements change, data
center managers can easily add
capacity without increasing the
system footprint. This approach
also allows for right-sizing of the
UPS, resulting in improved energy
efficiency and reduced power
expenditures.
ACTIve eCo-Mode™
An economy mode of operation
(eco-mode) changes the way a
double-conversion UPS is
employed to increase energy
efficiency and reduce the operating
expenses experienced in the data
center.
Eco-mode allows Double-
Conversion UPS systems to achieve
the highest possible efficiencies by
transferring the UPS to static
bypass during normal operation.
When power problems are
detected, the UPS switches back to
Double-Conversion mode. Until
recently, this transfer was not
seamless, because when the critical
load was being powered through
the bypass, the rectifier and inverter
were switched off. This resulted in
a slight inverter start-up delay and a
notch in the output waveform when
the critical load returned to
Double-Conversion mode. While
similar to the passive standby
topology previously described,
doeS yoUR UPS
SACRIFICe hIGh
AvAIlABIlITy FoR
hIGh eFFICIenCy?
UPS systems with conventional
eco-mode offer high efficiency,
but at the expense of
availability. Models with active
inverter eco-mode can deliver
even higher efficiency without
compromising availability.
State-of-the-art efficiency and
energy optimization modes
deliver high efficiency without
compromising availability.
whAT To looK FoR
• High efficiency in typical
load range: Don’t judge UPS
efficiency at full load
calculations – your system
rarely runs at full load.
Compare efficiencies in the
40-90 percent load ranges to
get a true picture of
operating costs.
• Active inverter eco-mode
with no break operation:
Active inverter technology
allows the inverter to
instantaneously assume the
load when switching from
double conversion to eco-
mode, and also provides a
cleaner waveform.
• Active inverter eco-mode as a
standard feature: If a system
employs a momentary-duty
static switch, you will
probably have to pay an
upcharge to get a
continuous-duty static switch
and eco-mode.
