DRIVES AND GEARS
WEG recently presented its new M (Mining)
series of slip ring motors for use in mining
The
new motor series
has a brush
compartment
with a completely new
design and a transparent window for inspection
and access. Commissioning is simplified by
combining the motor with a fully integrated
control panel as an option. At the same time,
operating and maintenance costs are reduced
and plant availability is increased.
The motor series is available in two versions:
either with a brush lifting device, or with brushes
in constant contact. The lifting mechanism of the
brush lifting device has been redesigned to make
it even easier to maintain. Compared to the
version with fixed brushes, the brush lifting
system requires less maintenance. In addition,
brush wear is reduced by fitted pressure springs.
An integrated control system is also available as
an option for the brush lifting device.
With its innovative design and new insulation
arrangement, the system offers alternative
advantages. For example, the cooling system of
the brush compartment is independent of the
motor cooling system, further boosting the
efficiency. The extended lifetime of the brushes is
one of the main advantages, but user access to
the brush compartment is also significantly
easier with this version. The brush compartment
achieves an IP rating of up to IP66.
The M Mining motors are available with
protection ratings from IP55 to IP66. They are
also protected by WEG paint systems that enable
operation in abrasive and humid environments
with atmospheric sulphur dioxide.
“In line with WEG’s ongoing innovation, the
addition of the WEG MVW3000 system brings a
range of benefits to customers,” says Moss. “It
gives WEG Automation
Africa even greater flexibility in our
market offering, further enhancing our capability
to provide customised solutions.”
The design is based on the well-known
cascaded H-bridge (CHB) topology, using
multiple low voltage power cells in combination
to achieve the desired voltage output. The input
switch, phase-shifting transformer and VSD are
fully integrated in a single MV panel.
“The WEG MVW3000 is particularly suited to
applications where there are standard motors
with no special insulation,” he says, “or where
existing motors are being modified for VSD
control.”
This VSD delivers high quality input power
using low harmonic multi-pulse transformers.
Users benefit from a high efficiency of over
Zest WEG VSDs perform at Ghana
gold mine
Two units of the newly developed WEG 11 kV
Variable Speed Drive (VSD) have been
commissioned in West Africa by WEG Automation
Africa, a member of the Zest WEG Group.
According to Kirk Moss, Senior Manager: Projects
and Engineering at WEG Automation Africa, the
new WEG MVW3000 VSD is a valuable addition
to its Medium Voltage (MV) VSD portfolio. The
first two 11 kV units produced are for 850 kW
ventilation fan motors in an underground gold
mine in Ghana.
36 International Mining | NOVEMBER 2019
The WEG MVW3000 VSD installed underground
at a gold mine in Ghana
96.5% throughout the entire load range, and a
power factor of more than 0.95 throughout the
entire speed range.
“The design includes power cells with long-life
plastic capacitors, which are more reliable and
last longer than dry type capacitors,” he says.
“They also have the advantage of not needing to
be reformed after long periods of storage.”
In standard configuration, the 11 kV VSD is
available from 40 A to 400 A – or 640 kW to
6,500 kW – although larger sizes are also
available if required.
Among the options on the WEG MVW3000 is
an automatic cell bypass solution. This ensures
minimal reduction in the output-rated torque so
that normal operations can continue. Redundant
power cells can also be added to the design to
ensure that 100% torque can be maintained.
Prior to delivery, all VSDs are fully load-tested in
WEG’s state-of-the-art facility in Brazil.
NORD and MAXXDRIVE XT
Bulk material handling in mining makes great
demands on conveyor belts and their drive
technology. Different conveyors are required
according to the direction of transport, volume
flow, conveyor length and construction. NORD
DRIVESYSTEMS says its reliable and robust drive
units ensure uninterrupted flow of materials.
They ensure a precise, dynamic flow of materials
which can be individually controlled.
This year, NORD presented a new industrial
gear unit series (MAXXDRIVE ® XT), which
optimises the proven modular system
for applications with high thermal limit
powers.
The NORD range has included
MAXXDRIVE industrial gear units for 10
years and over this period, they have
been further developed. The latest
generation supplements the long-
standing series with an application-
optimised two-stage right-angled gear
unit, which is especially suitable for
conveyor belt systems and can be
individually tailored to the particular
application. The power and speed range
was specially designed for industrial
applications in which small ratios are
required in combination with high
power ratings. This is the case for
example in the mining and minerals
industry. Here, robust solutions are
required which are resistant to dirt and
are reliable in rough operating
conditions. Special sealing concepts
which require as little maintenance as
possible are needed.
Output torques of the MAXXDRIVE ®
XT series range between 15 and 75 kNm with
ratios of 6.3 to 22.4. MAXXDRIVE ® XT industrial