Ground Power Unit(GPU)

GPUs provide either AC, or AC and DC
power for the operation of aircraft
avionics and engine start up on the
ground. Solid-state Ground Power
Units (GPUs) convert utility power into
400 Hz power for the aircraft. The GPUs take over when the Auxiliary
Power Units (APUs) onboard aircraft
are switched off, in order to reduce the
noise, the air pollution, and the
maintenance required by the APUs. The use of ground power also means
cost savings, the power can be
converted on the ground much
cheaper and much more efficiently
than by burning jet-fuel on the aircraft.
GPUs can also be mobile units, giving further flexibility. GPUs have also been
developed to meet the needs of
operators who have a requirement to
carry portable ground power aboard
the aircraft on a regular basis. These gpus are extremely powerful
for their size and weight and can be
loaded and carried aboard if required.
All units can be used plugged into a
110 power outlets to provide
continuous power for hangar or workshop applications, to test aircraft
systems. The units are usually
equipped with a 110/220 switchable
power supply. They are ideal for
working at remote locations. Older
GPU technology included a rotary converter, to convert the 50 Hz from
the gene- rator into the 400 Hz
required by the aeroplane. PCA/GPUs New GPU/PCA combination unit
designs are being developed to
accommodate some of the new jets. As
well as power, the units supply
preconditioned air PCA. In passenger aircraft such as Boeing
747s and A380s, the air conditioning
component is not such a necessity, as
the electronic components are not in
danger of overheating while being
active on the ground. Instead, the cooling unit serves to provide comfort
to those remaining inside the cabin of
the aircraft as it docks on the ground.
In a sealed cabin on a hot day, the
effects can be extremely
uncomfortable. Once again, it is the financial economies that the units
provide to the airlines in competitive
and straightened times that sell them.

Compare the cost of running air
conditioning from a ground-based
unit, rather than the aircraft auxiliary power units (APUs). At some airports, in more remote
locations, fixed GPUs are not always
available, and so portable PCA/GPUs
are used. These can either come in the
form of fully fitted trucks, complete
with a diesel generator, converter, and pressurised air conditioning unit
installed. Otherwise, the units may
come in the form of a trailer, which can
be towed behind any vehicle. Future developments are guaranteed,
because those who concern
themselves with noise at city airports
are increasingly against the Ground
noise from GPUs, which as we have
already established, are significantly quieter than running the aircraft. Ground Power Units GPUs are, after all,
small diesel powered generators used
as we have seen, to power aircraft on
the stands where Fixed Electrical
Ground Power (FEGP) is not available.
FEGP uses silent mains electrical supply. Pressure groups continue to
monitor the use of GPUs and FEGP
availability, ensuring that the use of
GPUs is minimised wherever possible,
imposing even tighter controls on GPU
usage.