Plant&Equipment

Special report
A revolution in
cable detection
(continued....)
(like that of a discus thrower’s
field), that is coloured from yellow
through to orange and then red.
As with parking sensors the
display is inactive if no signal is
present . As soon as a signal
is detected the first yellow line
appears and the display moves
through amber and red as the
service gets nearer.
Cable Detection can either
install the device directly into
the machine’s electrical supply
or EZiDIG can simply use the
machine cigarette lighter / power
output socket.
The device has been designed
to allow the user to adjust the
sensitivity of the EZiDIG so as
to be able to work in an area
relatively congested with buried
services. So the user can dig
a trench parallel to an existing
metallic service by setting the
sensitivity to show that the
other service is present but
only creating a warning if the
operator starts to move nearer
to the existing service i.e. off the
parallel line.
Field trials
To test how well the EZiDIG
system works, Cable Detection
have been working with Dr
David Edwards of Loughborough
University, to carry out field
trials so as to provide an
independent view of this new
detection equipment.
To do this, in November 2007,
Dr Edwards visited a Birse Civil
Engineering site in Telford, during
a live trial with a sub-contractor
called JRB (Stoke) Ltd.
The tests were supervised by
Mr Chris Evans of JRB (Stoke)
Ltd and excavation works were
conducted by Mr Cathill Kelly.
Mr Kelly is a skilled operator with
over 15 years experience in the
industry and he had previously
been trained in the safe use
of the EZiDIG by Mr Richard
Fling, Product Manager,
Cable Detection.
The whole process of connecting
the device to the machine and
calibrating its sensitivity took
no more than ten minutes to
complete. A series of three trials
were then carried out to measure
the performance of EZiDIG
with a final trial to measure its
robustness to impact shock.
Trial one involved working
parallel to an excavation, to try
and detect a known three-phase
electric service cable that was
located within it.
Trial two involved detecting the
same cable but when working
across (perpendicular to) the
same excavation.
Trial three measured the
performance of EZiDIG when
working between two services,
one hidden (a street light cable)
and the other under the same
conditions as in trials one and
two above.
Across all three trials the
equipment exhibited detection
accuracy, so long as the dipper
arm did not curl back towards
the cab too far (i.e. to produce
an acute angle with the body
of the operator cab). Under
circumstances where this was
allowed to happen, the cone of
detection was pointed towards
the machine’s undercarriage as
opposed to the ground. Hence, it
failed to detect the cable because
there was no service under the
slew drive of the machine.
EZiDIG also lived up to its name,
in that the operator easily adjusted
the sensitivity of the device
during excavation works to suit all
conditions encountered on site.
One concern raised by Dr
Edwards focused on the almost
constant audio alarm emitted
from the device. This background
noise could be a source of huge
annoyance and past research
conducted by Dr Edwards has
revealed that noise can actually
have an adverse effect on
operator safety. In such instances
operators might perceive a source
of constant noise as an annoyance
and either try to vandalise the
source or ignore the audible
signal it is attempting to convey.
To address this issue, Cable
Detection have catered for
potential noise pollution by
allowing operators to set the
point at which the audible alarm
is activated.
18
February 2008