Mobile Drill Rig Uses Electric Drive
For Fume-Free Operation
Redevelopment of city centre locations
can require drilling of deep bore holes to
check the suitability of the soil and bed
rock for supporting new buildings. If a
site requires a comprehensive geological
survey it may be necessary to drill inside
existing buildings. However, most drills are
diesel driven, meaning the exhaust fumes
have to be extracted to the outside, a task
that is difficult, time consuming, expensive
and often not entirely successful.
commercial accommodation. There are
several equally ambitious building projects
nearby, including the new US Embassy and
the long-awaited redevelopment of the
redundant Battersea Power Station into a
cutting edge mixed use facility.
A new type of drilling rig, developed with
the help of electric motor company Exico,
can be used indoors without the risk of
filling the building with diesel exhaust
fumes.
“Normally the drilling rigs used by
geological surveyors are driven by diesel
engines,” he says. “This is fine if you are
working out of doors and the exhaust
fumes can dissipate on the wind. “However,
if you attempt to use such equipment
indoors the fumes quickly cause problems.
It becomes necessary to use ducting and
fans to extract the fumes. This can cause
delays to the schedule, add costs and is
often difficult to achieve.
Planning the redevelopment of London’s
New Covent Garden fruit, vegetable
and flower market has required a
comprehensive geological survey to be
commissioned, right down to a depth of
50m. So a specialist drilling company was
brought in to collect soil and rock samples
from multiple deep drillings across the 57
acre site.
New Covent Garden market, in Nine Elms
on the south side of the River Thames,
has been in operation since 1974 when
the old site was closed to make way for
retail and leisure businesses. It is home
to the 200-plus independent traders that
supply London with nearly all of its fruit,
vegetables and flowers.
The redevelopment of New Covent
Garden is scheduled to take 10 years
and cost £2bn. It will see the market
facilities modernised to make them more
efficient and free up 20 acres of land for
nearly 3,000 homes and 115,000 sq ft of
Jerry Hodek of Exico explains that the
geological survey has to be thorough and
requires many of the exploratory bores to
be drilled inside existing buildings.
With so many holes to be drilled across the
New Covent Garden site a solution was
required that would effectively overcome
the fume problem yet be quick to set up
and easy to operate, and an electric motor
drive provided the answer.
Kostal’s Inveor inverters are
designed to be mounted directly
onto the motors they are
controlling, in place of the
motor’s usual terminal box.
Normally inverters are located in
a separate, remote control cabinet,
but this would be an impractical
configuration for portable
equipment such as on-site drilling
rigs.
“Motor mounted inverters are subjected
to significant levels of vibration and heat,”
says Jerry. “The Kostal units are built to
be so robust that they can cope with the
vibration and also have a large heat sink,
which in this case we have augmented
with a cooling fan to provide a constant
airflow over the unit.”
The variable speed, electrically driven
drilling rig is proving its worth on the New
Covent Garden project, reliably drilling
bores to precise depths and helping the
surveyors keep to a strict schedule.
www.exico.co.uk
“The electric motor is fitted onto the rig in
place of the diesel engine,” explains Jerry.
“This can be driven from a three phase
mains supply or a mobile diesel generator
located outside the building, where fume
build up is not a problem.”
In fact the motor that Exico supplied is a
four pole 18.5kW 400/690V 50Hz machine,
fitted with an integral inverter to turn it
into a variable speed unit. The inverter,
made by Kostal was also supplied by Exico.
Issue 23 PECM
101