and facilities managers, the respondents
ranked energy efficiency fourth in
priority. Availability was the overall,
overriding concern. This is partly due to
the costs of a data centre outage, which
can run into hundreds of thousands of
pounds. Yet concerns about damage
to the enterprise’s reputation are often
even greater, and with good reason. A
data centre failure that takes out a bank’s
ATMs and denies customers access to
their accounts is an event that can cause
real problems for thousands of users
and possibly make the national news
headlines.
That’s not to say that operators have
no interest in energy saving or green
branding. They’re certainly interested
in achieving these objectives, but only if
they can do so without putting their data
centre’s availability at risk. Wouldn’t it
be great if possibilities existed that allow
energy savings to be made without
threatening the facility’s availability?
In fact, such possibilities do exist, and
are currently implemented in m any data
centres. Part of the approach involves
using sensors and software to monitor
and modify the behaviour of a centre’s
IT hardware, power and support
equipment, and environmental control.
Such strategies are complemented by
the availability, efficiency and flexibility
of the equipment they are working
with. This applies not only to the ICT
hardware itself, but also to the UPS and
cooling equipment that supports it.
As UPSs tend to be large-scale
devices handling high power levels, their
performance can have a significant
impact on that of the entire data centre.
Therefore, installing UPS systems that
are efficient while also being highly
available and flexible can make a
significant contribution to meeting the
twin demands of any data centre –
high efficiency with uncompromised
availability. Accordingly, we can look
at the UPS topologies that allow these
objectives to be realised.
Modern UPS Technology
One of the most important
developments in recent years is
the advent of transformerless UPS
technology. Facilitated by advances
in power semi-conductors, it offers
several key advantages over earlier
transformer-based solutions. Efficiency
is improved by up to 5 per cent and
remains consistent over the entire load
spectrum. Power factor becomes closer
to unity and independent of UPS
loading, reducing the input current
magnitude and allowing reductions
regarding cabling and switchgear sizing
and possibly reducing electricity costs.
Input current harmonic distortion is
also reduced.
However, one of the main
advantages is the huge reduction in
size and weight that transformerless
technology allows. The UPS footprint
can be halved, while its weight reduces
by about 75 per cent. These reductions
are so significant because they have
facilitated the concept of modular UPSs
and a completely new approach to UPS
implementation. Instead of a large,
UPS AC-DC efficiency curves – transformerless v. transformer-based
www.netcommseurope.com
A modular system can be configured to the existing load requirement
single, inflexible floor-standing module,
a UPS can be built up as one or more
complete, self-contained modules in a
19” racking frame.
This is demonstrated in UPS
Ltd.’s PowerWAVE 9500DPA high
power UPS. It can start as one frame
containing a single 100 kW module; the
frame can then be scaled vertically in
100 kW steps up to its 500 kW capacity.
If preferred, the system can be run in
redundant mode, supporting a load
up to 400 kW in an N+1 redundant
configuration. Horizontal scaling is
also possible – this means that up to six
frames can be paralleled to provide up
to 3 MW power capacity.
The modular design permits UPSs
with very high power availability,
particularly if they support ‘hot
swapping’. A module is hot swappable
if it can be inserted or removed from
the host UPS frame without depriving
the critical load of power or transferring
it to the raw AC mains supply. Safe
electrical disconnection and isolation
without the risk of error-induced
NETCOMMS europe Volume V Issue 6 2015 41