Network Communications News (NCN) May 2016 | Page 21

power testing

end of data centre design alongside
architects and consultants. We have
worked with many consultants to ensure
they meet initial and future design
developments. With city centre living
on the increase we are also finding that
there is an increased need for reduced
sound pressure levels.

Power factor

Modern life is reliant on the continued
performance of a data centre.

There are various options with regards
to power testing – resistive and reactive.
The most common form is to use a
resistive loadbank to run the prime
mover, connected at the generator’s bus.
However, this fails to replicate the actual
stresses produced during real world
generator operation. A resistive-reactive
load test of an installation’s power
system can accurately simulate the
system’s response to a changing load
pattern, such as would be encountered
during a real power failure.
However, as resistive loads are
usually only a small part of any data
centre’s total power consumption
the influence of a lagging power
factor (pf) <0.8 due to reactive loads
is underestimated or even ignored.
Generally the only equipment operating
on a resistive-only load are incandescent
lights and electric heaters; these units
draw a steady supply of electricity from a
generator, but do not produce the large
block loads that truly test a generator’s
performance. A resistive load test will
verify that a generator’s prime mover is
working, but it will not identify how well
it will actually perform when exposed

F E AT U R E

to the real reactive load pattern.
Resistive/reactive testing can also reveal
additional stresses (and predict pending
failures) of a system’s switchgear,
alternators, and other systems that
resistive-only testing cannot.

Not just power security
In addition to the commissioning of
emergency power systems, loadbanks
have a crucial role in air conditioning
testing. Air conditioning plays a vital
part in keeping server halls at stable
temperatures and humidity levels
and more often than not is designed
with extremely high levels of capacity,
redundancy and future expansion
in mind. With millions invested in
the most advanced technology,
the air conditioning plant must be
commissioned against stable and
traceable heat loads.
Resistive only loadbanks can provide
a portable and highly controllable heat
source to allow air conditioning systems
to be thoroughly commissioned against
their design criteria. The loadbanks are
small enough to be placed directly inside
the server halls and can be controlled
independently at 1kW increments, or
operated as multiple units at the same
or differing kW heat load increase and/or
decreases. The distributed heat can then
be measured by various temperature
sensor and probes, or by thermal
mapping devices, to ensure the airflow
and cooling is evenly distributed and that
there are no ‘hot-spots’ around any vital
equipment enclosures.

Loadbanks are now
more frequently
being specified at
the front end of
data centre design.

duration of their existence, hence
reliability is crucial. In order to ensure
this, the infrastructure needs to be
systematically tested on a regular basis.
This means that the electricity powering
the equipment needs to be replicated
as realistically as possible. This is where
loadbanks play a vital role.
Traditionally data centre loadbanks
have been associated with the
healthcare and finance industries,
however we have found that the sector
has now overcome these expectations.
Rather than specifying as a retrospective
piece of equipment, as in the early days,
companies are now realising that they
have installed all of the necessary power
and that it is too important not to test.
Therefore loadbanks are now more
frequently being specified at the front
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21/04/2016 17:12