Technology and innovation
Debmarine Namibia, a joint venture
between the Namibian government
and diamond giant De Beers, operates
five offshore mining vessels, which
mines diamonds from the ocean off
the west coast of southern Africa.
One of these vessels, Debmar Pacific,
was experiencing problems with its
electrical system. Debmar Pacific is one
of the oldest vessels, having been built
in 1977, and the vessel was having
problems with a lighting circuit, in
which several transformers were
malfunctioning because of poor power
quality supply. This is a classic symptom
of an electrical circuit experiencing
harmonic noise-related problems.
Actom Energy, electrical engineering
specialist in South Africa, was chosen
to design, manufacture, and install
an active harmonic filter control
panel to the vessel to alleviate this
problem. Actom needed to source
a harmonic filter fast, and based on
a recommendation from De Beers,
called upon CP Automation. Using the
information supplied by Actom and De
Beers, CP Automation advised the use
of an ADF P100 active dynamic filter
by Comsys.
Harmonics becomes a problem because
of the use of variable-frequency drives
(VFDs) and other non-linear loads.
A load is considered non-linear if its
impedance changes with the applied
voltage. This change means that the
current drawn by the non-linear load
will not be sinusoidal, even when it is
connected to a sinusoidal voltage.
Non-sinusoidal loads contain harmonic
currents that interact with the impedance
of the power distribution system to create
voltage distortion and power quality
problems, which heat the transformer.
This explains why the previous
transformers malfunctioned in the
lighting circuit on the Debmar Pacific.
Harmonic filters — as the name
suggests — remove harmonics. However,
they also correct the phase of the
fundamental currents, converting non-
linear loads into linear ones. They cancel
out the noise and keep the transformers
cool and working efficiently.
“We cannot stress enough how
much of a positive impact the
right harmonic filter can have on a
company’s environmental performance,
lowering energy consumption and
improving productivity,” says John
The ADF P100 harmonic filter, supplied by CP
Automation, on-board the Debmar Pacific.
A cure for vessels’ lighting
Mitchell, business development
manager at CP Automation. “With
this in mind, we were confident that
the ADF P100 was a perfect match
for Actom’s project, and that it would
put an end to the previous transformer
issues,” he adds.
Exxaro has delivered three more
cranes for its Grootegeluk coal
operation close to Lephalale in
the Limpopo Province of South
Africa. The company placed an
order with Johannesburg-based
Condra to manufacture high-lift
overhead travelling cranes for
vehicle workshops late last year.
This brings the total number
of cranes ordered by Exxaro
and supplied by Condra since
2016 to six, valued at about
R10-million.
The first of the new orders,
for two cranes, was secured by
authorised Condra distributor
H&H Specialised Services in
November of last year. A third
crane was ordered in December
and a further order for a fourth
machine is expected soon.
H&H Specialised Services
will supply staff and technical
expertise to install and
commission all new cranes,
the first two of which have already been
delivered. Both are 50-ton double-
girder electric overhead travelling cranes
[38] MINING MIRROR JULY 2018
Exxaro’s 18.4m span 50/20-ton machine featuring
variable‑frequency drives on the main lift, long travel and cross
travel to facilitate precise positioning of very heavy loads,
under test in Condra’s Johannesburg factory mid-April 2018.
with standard two‑speed hoists, and
both have spans of 18.4m.
The third crane is an 18.4m span
50/20-ton machine featuring
variable‑frequency drives on the main
lift, long travel and cross travel to
facilitate precise positioning of very
heavy loads.
More cranes for Grootegeluk