Document1 2/9/08 4:45 pm Page 1
DRIVES AND CONTROLS
DRIVING FORCE
Siemens fitted the first
Bucyrus 8750 with the
new drive system for
use in Shuenhua
Group’s Zhungeer
mine,120 km south of
Hohhot, the capital of
the Nei Monggol
Province (Inner
Mongolia)
With today’s high energy costs, it is especially
important to choose the right equipment to drive and
control mining machines – John Chadwick considers
some of the latest technology offerings
U
ntil now, draglines all over the world
were equipped with geared drive
systems motors only. But now Siemens
and Bucyrus have jointly developed a gearless
AC drive system – Simine DRAG. One of the first
such systems is in China’s Zhungeer coal mine,
but draglines already in use can also be retrofitted.
The drive systems with a performance of 9.7
MW are used for the hoist and drag motions. By
eliminating the gears, maintenance and
operating costs are reduced in comparison to
conventional drives. The extended service
intervals reduce maintenance and increase the
excavator’s availability. Gearless AC drive systems
also offer up to 20% more efficiency and use
less energy, thus reducing operating costs.
Simine DRAG combines reliable electronics
and controls proven in thousands of Siemenspowered locomotives and mining shovels, with
gearless ring motors that have been in reliable
service in grinding mills, mine hoists, chain
excavators and conveyors for more than 25
years. Siemens combined these proven, reliable
components into this new, revolutionary
dragline drive system.
The dragline’s ring motors are fitted with
nine winding systems. The ring motors were
delivered in two halves and had to be
assembled on-site. The assembly was especially
difficult as 90% of the work had to be done
outdoors. The roof was added later and all
hoisting jobs had to be carried out by mobile
crane. Bad weather conditions and coal dust
from the mine nearby further impaired the
work. Sandstorms occurred almost every day
and heavy winds made assembling the poles
difficult. “Testing was done sometimes under
extreme conditions. Aside from some starting
problems, the unit has proven to be very
successful. A top result for a new technology!”
explains project director Ralf Lechtenfeld.
AC IGBT inverters supplied and installed by
Siemens Energy & Automation in Atlanta
control the drives. The excavator has been in
operation since December 2007.
To achieve high uptime and short MTTR
(Mean Time To Repair), Siemens offers what it
claims is “the most advanced and user-friendly
maintenance computer in the industry. It
shows the mine electrician where the problem
is, and which part is needed to fix it. The
dragline system also seamlessly integrates with
Siras and Midas. Siras remote diagnostics uses
Internet technology to keep the factory on the
machine.”
Siemens and Bucyrus service technicians and
other experts can log on from around the
world and can do the same work as the
electrician on board the dragline, with the
exception of tightening a screw. Midas
harvests a wealth of data during normal
operation and makes it available for
productivity analysis and optimisation.
Turning to electric shovels, Boris Rathmann
of ABB Automation explains the latest in
shovel drives from ABB. “Since 1999, the
Center of Excellence Open Pit Mining of ABB
Automation Cottbus has steadily expanded its
position in the market for discontinuous open
SEPTEMBER 2008 International Mining 91
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DRIVES AND CONTROLS
P&H Mining Equipment, a global leader in the
manufacture of electric mining shovels, is the
most important partner for the supply of ABB
Drives for Mining. P&H uses AC drive Technology
for the 4100 Boss shovel in an oil sand mine and
was able to increase the productivity (payload)
with highest availability
pit technology. ABB has delivered completely
new drive systems for 15 electric rope shovels
and two draglines. The experience from this
successful project forms a solid base for further
expansion in this market segment.”
Adverse conditions for open pit machines,
such as dust, extreme temperature
fluctuations, heavy shock and vibration loads
require a special design for state-of-the-art
power electronics. The new ABB frequency
converter ACS800 had to prove its worthiness.
Based on vibration measurements from various
open pit mining machines and subsequent
simulation calculations, the control system was
tried and tested for its suitability under these
strenuous conditions. The results were used to
mechanically reinforce the design of the
converter switchgear. Concluding test lab
examinations proved that ABB Drives for
mining meet the high demands of open pit
mining in terms of shock and vibration
resistance.
The excellent communication between the
ABB companies in Germany, Brazil and Israel
yielded extremely short installation and
commissioning times at consistently high
quality. The follow-up order for a second
excavator in the same Brazilian mine proves
the high customer satisfaction.
During ongoing projects e.g. in Israel, the
ABB drive system’s electrical concept could be
further enhanced. Unlike the previously used
system, a new regenerative supply unit (AFE Active Front End) recirculates power to the
mains generated by the drives during shovel
92 International Mining SEPTEMBER 2008
operation. Only three months after
commissioning, this new concept could save
23% of the energy expenditure – significantly
more than initially expected.
Dietmar Simke of the same company notes
that “in spite of more and more common use
of variable frequency controlled drives in open
pits, drives with slip-ring motors still represent
a broadly used technical solution. ABB
Automation [and predecessor companies] has
integrated more than 2,000 slip-ring motor
drives for overburden conveyor bridges, bucket
wheel excavators, bucket chain excavators,
spreaders and belt conveyors from 1970 until
now.”
ABB Automation took up the well known
idea of using power electronic components to
control the starting process of slip-ring motors
in order to achieve better control and reliability
of drive systems with slip-ring motors currently
in use or to be built in the future.
The starter consists of a six-pulse rectifier
with downstream pulse-width controlled single
resistor chopper.
A rotor resistor selectively and continuously
influences the torque generated by the motor.
As in circuits with liquid starters or staged
resistor starters, the motor current which can
be measured easily, will be used to control
motor torque. Depending on the drive system
requirements simple or more complicated
starting procedures can be applied. In detail
that may be:
■ Motor-start with constant or defined
changing motor torque, independent from
load torque
■ Time scheduled motor-start, independent
from load torque
■ Speed controlled motor-start with variable
speed set point
■ Combination of these procedures and
special starting procedures (heavy duty starting
service)
■ The possibility of taking targeted influence
to the torque generation in drive systems with
DC injection breaking.
In all cases one has to consider the limited
control range to the minimal generated motor
torque, caused by the dimensioning of the
resistor. The driving forces for the development
of an electronic starter included:
■ Improved possibility for well defined start up
behaviour
■ Reduce maintenance by replacing the
heavily wearing step contactors for staged
resistors through an electronic circuit
■ Safe forecast of the availability of the starter
resistor for further starting procedures by
improving the temperature measurement of
the single resistor.
Moventas Santasalo supplies customized
heavy duty mechanical drive solutions for
mining and mineral applications as well as
start-up and customer support services labeled
Figure 1: Principle circuit of an ECOSS electronic
compact starter for slip-ring rotor drives
Document1 2/9/08 4:58 pm Page 1
DRIVES AND CONTROLS
with the Santasalo trademark. The
company specialises in the design and
manufacture of large diameter multisegmented ring gears used to rotate large
drums, kilns and mills. The company is
the original equipment manufacturer for
the multi-segmented ring gear concept
for mineral industry applications. In
addition to large Santasalo spur multisegmented ring gears, Moventas is now
also able to offer helical multi-segmented
ring gears. Moventas Santasalo says its
“helical multi-segmented ring gears run
smoothly and quietly, offering a
refinement over spur gears in certain
applications. Developed to meet
individual needs, Moventas can deliver
the best solution with helical or spur ring
gears for both new installations and
replacements.”
The multiple segment design of
Moventas ring gears enables higher
precision machining with more accurate
tooth geometry for diameters of 3 m and
up, no upper limit exists. Pioneered by
Santasalo, today part of the Moventas
Group, multi-segmented ring gears have
been designed and manufactured in
Finland for over 30 years. With more than
500 operating worldwide, the design has
proven durable and reliable.
Moventas Santasalo’s multi-segmented ring
gear consists of 10 to 20 segments bolted
together to make immensely strong and precise
large diameter gears. The length and number
of segments depends on gear diameter and is
optimised for each application. The result is a
significant reduction in lead-times as well as
easier and less costly transportation compared
to single piece castings. Assembly is also
simplified, with the compact segments being
easier to lift and position. The ring gear and
pinions are usually delivered with the main gear
units including auxiliary drives and bedplates.
Since Moventas can supply the complete
package, straightforward and trouble-free
installation is assured, leading to faster start-up
and optimal running.
Gear wear is minimised by using
Austempered Ductile Iron (ADI) in gear
castings. ADI has the high strength to weight
ratio required together with high resistance to
fatigue and wear for long ring gear life. Highly
accurate production and assembly techniques
minimise vibration and further enhance the
long service life of the gear. Condition
monitoring tools enable the performance of a
drive to be followed either in real-time or as a
part of regular inspections. Should damage to
a gear occur, individual segments could be
94 International Mining SEPTEMBER 2008
Moventas Santasalo's multi-segmented ring gear
replaced instead of changing the whole gear.
This makes it possible to carry spare parts for
critical applications if required. The reliable,
trouble free operation of Santasalo multisegmented ring gear packages is supported
throughout their life-cycle by a comprehensive
range of services, with a strong focus on
condition management and proactive
maintenance.
Bonfiglioli is custom-engineering new
combination drives for materials handling
and mining applications, which demand
high levels of cost-efficient power from
compact installations. One recent
combination employs a Trasmital planetary
drive coupled with Bonfiglioli’s new
generation heavy duty HDO/HDP helical
series to produce an apron feeder drive
that offers the best features of each.
Bonfiglioli’s modular Trasmital 300
multipurpose planetary drives – known
for their torque density and compact
dimensions – can be coupled with HDP
Parallel Shaft and HDO Bevel Helical
units in sizes up to 72,000 Nm to
produce outstanding reliability and
torque densities to record values, says
Bonfiglioli Transmission (Australia)’s
Managing Director Malcolm Lewis.
“Such combinations produce powerful
high torque drive combinations
especially suitable for low speed
applications. The power of such
combinations will be further extended
this year with two new HDO/HDP sizes
to be released that will bring the torque
capacity of the range up to an
impressive 140,000 Nm,” he says. “The
versatile HDO/HDP drives combine
brilliantly with the 100% modular
Trasmital 300 series of multipurpose
planetary gearboxes, which is available in 14
basic sizes, with output torque up to 540,000
Nm and transmissible power up to 450 kW.”
The Trasmital 300 series gearboxes - which
can also be combined with Bonfiglioli’s C1, A
and F helical gearboxes - are especially
suitable for applications requiring high
reduction ratios, high transmissible torque and
high radial loads on output shafts. The
Transmital 300/HDO combination gearmotor being
used in an apron feeder application
Document1 2/9/08 4:59 pm Page 1
DRIVES AND CONTROLS
combination drives, tailored to customer
requirements, feature excellent torque
distribution across their entire ratio range of
the HDO/HDP drives. Their gear ratios are laid
out in close progression and the drives having
a rugged capacity to cope with the shock and
impact of intermittent loads.
At AIMEX, Danfoss displayed its new VLT
family of AC drives. The drives range in
capacity from 0.18 kW to 1.2 MW and are
highly efficient, with 98% of the power being
transferred to the motor. Even this small
percentage can mean significant heat loss on a
large drive, but this is managed by transmitting
85% of the excess heat through the backchannel heat sink, removing it from the drive,
panel and working environment.
Feature of the VLT drives that minimise
installation space include built-in DC coils for
harmonic suppression (rather than external
AC-coils), built-in RFI filters, and the optional
placing of input fuses and the mains
disconnect switch within the standard
enclosures. Standard enclosures sizes are
available with an IP21 (NEMA 1) or IP54
(NEMA 12) rating.
Time savings in installation, commissioning
and maintenance of the VLT drives are
provided by an intuitive user interface using an
award-winning control panel, a single drive
type for the full power range, a modular
design than allows fast installation of options,
automatic tuning of PI controllers and virtually
maintenance-free operation through robust
design and efficient monitoring.
Turbo couplings
Voith says type TPKL turbo couplings “are
extremely robust and provide high availability,
which has contributed to increased production
in many mines. References span the globe from Australia and South Africa to Spitzbergen
and the USA. To meet special customer
Weighing in at nearly 65,000 kg this girth gear set a
new record at David Brown Gear Industries in South
Africa. This was an order worth $1.3 million from F L
Smidth Minerals for a project in Armenia. The single
helical SAG mill girth gear which is cast in four pieces
has 362 teeth, 0.75 DP, 863.6 mm face width, 12.4
m outside diameter and a 10.5 m diameter bore. It is
manufactured from steel with a hardness range of
269/321 BHN and the gear teeth are cut to AGMA
grade 10. David Brown is also supplying three mill
Flotation Cell Drives
Drum Drives
Crusher Drives
Agitator Drives
Rolling Mill Drives
Conveyor Drives
Coiler Drives
Drum Drives
Power Player in Mining and Metallurgy
Complete drive packages for worldwide projects throughout the industry – Full service support
KUMERA POWER TRANSMISSION GROUP
Kumera Drives Oy, Finland
Kumera Antriebstechnik GmbH, Austria
Kumera AS, Norway
Kumera Shanghai Representative Office, China
96 International Mining SEPTEMBER 2008
Document1 2/9/08 5:00 pm Page 1
requirements, Voith Turbo offers versions with reduced height and an
external tank, to enable use on a wide range of foundations and base
frames. Space and adaptability play a crucial role, particularly when it
comes to retrofit solutions.”
Voith’s TPKL family of fill controlled turbo couplings has a new
addition, the new, alignment free version (TPKL-T). This is a response to
demand from users. Since its introduction to the market in 1998, TPKL
couplings have a proven history of performance and reliability.
TPKL-T fill controlled turbo couplings are fed by an external oil supply
system. The oil supply system is located near the drive assembly and uses
several flexible hydraulic hoses for easy assembly and connection to the
TPKL-T housing and oil cooler. This allows optimum placement of the oil
supply system and associated electrical components. The result is good
accessibility around the drive. The actual drive, made up of the motor,
Voith TPKL-T turbo coupling and gearbox, is centrally supported by a
standard torque-arm support below the drive. This means that not only
the coupling, but also the entire drive can easily be attached to and
detached from the drive pulley on site.
The first 12 drives with this new ‘tunnel design’ are being installed in a
mine in Pennsylvania, USA, which produces in excess of 10 Mt of coal. A
follow-up contract for a further 32 Voith TPKL-T turbo couplings has
already been agreed; the mine wants to use the tunnel design as
standard on all new belt drives. Meanwhile, other mines have expressed
interest in the benefits of the Voith TPKL-T and are considering this drive
design for future conveying requirements.
The successful basic TPKL turbo coupling was specially developed as a
compact drive solution for belt conveyors and has been used on every
continent since its launch. The TPKL series has been installed in over 250
drives with a power range up to 250 kW @ 1,500 rpm or up to 430 kW @
1,800 rpm. In addition, over 150 drives are in operation with a power range
of up to 500 kW @ 1,500 rpm or 860 kW @ 1,800 rpm. Since launch, the
series has been supplemented to enable Voith turbo couplings featuring fill
control technology to be used on belt conveyors with an individual drive
power of 2,400 kW (1,200 rpm) or 4,700 kW (1,500 rpm).
Baldor Electric, manufacturer of energy saving industrial electric
motors, drives, power transmission products and generators, has
introduced the new Dodge MagnaGear XTR. This extra tough reducer
has been engineered to offer maximum reliability and superior
performance in tough, high torque applications.
The MagnaGear XTR is available with parallel shaft or right angle
configurations and will initially offer torque capacities up to 104,000 Nm
(920,000 lb-in). The modular design of the product allows for multiple
mounting configurations and can be used with a variety of soft start
mechanisms, making it ideal for a variety of conveying applications.
Designed to meet or exceed AGMA and international standards, this
heavy duty, cast iron product features gearing that is carburised,
hardened, and precision ground. Tandem HBNR lip seals are standard for
extra protection, all bearings exceed AGMA standards for L10 life, and
all components are power matched for optimum performance at a lower
installed cost.
In sizes over 44,060 Nm (390,000 lb-in), the MagnaGear XTR features
the proven Dodge planetary design, providing a compact, durable, light
weight and economic solution for high torque applications.
A complete line of engineered accessories are available including,
internal lift-off style backstops, cooling systems, rigid couplings, torque
arms, swing base mounts, tunnel housings and baseplates.
Brevini’s Posiplan is a new range of ultra-compact planetary and bevel
helical gearboxes for industrial applications. These new gear reducers,
protected by a specific patent, feature a combination of planetary and
helical/bevel gears that takes advantage of the strengths of each
SEPTEMBER 2008 International Mining 97
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DRIVES AND CONTROLS
Voith's TPKL family of fill controlled turbo
couplings has a new addition - the
alignment free version (TPKL-T)
technology: compact size,
reliability and easy maintenance.
Designed primarily for shaft mounting,
ultra-compact gearboxes optimise
characteristics suitable for this type of
application, which is extensively used in a wide
variety of sectors. In mining this would be, for
example, in washing systems, drying furnaces,
certain crushers, belt conveyors, bucket
conveyors and more.
Proportional directional control valves by
Brevini Hydraulics, with inlet flows of 140 and
240 litres/min are used for a wide range of
applications such as drilling machines. All the
components of the valves are exclusively
designed by the company, which holds four
internationally recognised patents.
The new AquaMaKKs water cooled clutches
and brakes from Wichita Clutch are air, hydraulic,
98 International Mining SEPTEMBER 2008
or spring set actuated,
featuring copper wear plates
optimised for heavy-duty
continuous slip tension
applications. AquaMaKKs™ consist of a series of
alternating friction discs and water jackets.
Torque is transmitted by applying axial force from
the pneumatic, hydraulic, or spring set actuator.
Copper wear plates provide excellent heat
dissipation.
Simplicity of design with fewer parts
simplifies installation and maintainability,
saving both time and money. Shim design
makes it easy to maintain and adjust for wear.
A unique patent pending water jacket
design ensures high heat absorption and
torque stability, allowing for greater heat
dissipation over similar sized
competitive units. Unique
mounting pattern enables direct
replacement to Wichita or
competitors’ units, requiring no
design changes for the customer.
Ameridrives Couplings’
TorqueSentry is a torque limiting coupling. Its
main purpose is to avoid catastrophic failure or
destruction in the case of overload of the
driveline, which can result in injuries or
unexpected and expensive downtime of the
entire system. The design offers several
distinctive features that include immediate and
precise point of release, adjustable release
torque, selected release torque remains
constant and is not susceptible to fatigue,
back-lash free power transmission and minimal
maintenance requirements.
The principle of the TorqueSentry is very
simple, but highly effective. A pair of tapered
pressure rings is forced over a tapered sleeve
by oil under pressure. The pressure ring is then
locked in place by mechanical fuse pins. This
Document1 2/9/08 5:02 pm Page 1
The new Dodge MagnaGear XTR
produces a friction connection between a
sleeve and a shaft. At overload, the coupling
instantaneously releases the fuse pins and
interrupts the drive.
Avtron’s AV850 SMARTach II heavy mill
duty modular magnetic encoders fit standard
216 mm FC-Face motors. Other models, from
115 to 318 mm are available to fit other motor
sizes. The AV850 is designed to eliminate
encoder failures. All AV850 electronics are fully
encapsulated with no moving wearing parts.
Avtron reports that AV850 sensors locate
over four times “farther from the rotor than the
competition; no more sensor/rotor grinding! The
AV850’s high-power outputs have over 50 times
more capacity. Miswiring an encoder is common
– and it shouldn’t cost you time or money. The
AV850 has full output short circuit and reverse
voltage protection, plus surge protection.”
AV850 SMARTach II sensors digitally selftune the outputs to eliminate drive trips
caused by poor encoder signals. AV850
sensors feature great diagnostics. If the
encoder signal is not ideal, the alarm output
and LED inform the machine operator that the
encoder should be checked, before a failure
occurs! The AV850 even checks the rotor
position before running starts.
Stopping overheating
WEG has developed an innovative solution to
the problems of overheating in AC induction
motors at slow running speeds under
frequency converter/variable speed drive
control. Termed Optimal Flux™ Technology
(OFT), the WEG solution eliminates the cost
and size penalties of some manufacturers and
maintains the reliability and life of the motor
by limiting any temperature rise at low speeds.
Using the OFT solution for variable frequency
drives allows WEG to team its standard off-theshelf Totally Enclosed Fan Cooled (TEFC) NEMA
Premium Efficiency, NEMA High Efficiency and
IEC Premium Efficiency EFF1 induction motors
as an option with the CFW-09 and CFW-11
drives. This enables the motors to run at least
11% cooler over the entire speed range than
traditional constant flux strategies offered by
other manufacturers. Typical applications
include positive displacement pumps,
compressors and conveyors.
Sebastião Lauro Nau, WEG Motors R&D
Manager commented: “Typically each 10°C
reduction in operating temperature doubles the
life of an induction motor, so WEG can offer a
three-year extended warranty, with less
maintenance costs and down time. Use of
standard motors and spares also reduces the
cost of spares and enables the motor to be used
in a wider number of applications on a site.”
With all these benefits, the WEG NEMA
Premium / Optimal Flux CFW-09 Variable
Frequency Converter combination costs around
10% less than competing inverter class drive
solutions, while lasting longer and saving space.
Variable speed converter drives were
developed in the 1990s and enabled the
reliable, low maintenance TEFC AC induction
motor to replace DC motors in applications
where speed variation was required to match
application and improve energy efficiency over
constant motor speed operation.
However, the problems of overheating arise
stop wasting money!
Vacon variable speed AC drives are a perfect companion to
control your AC motors. They improve process control and
save energy.
Vacon Liquid-Cooled AC drives reduce the operating and
maintenance costs of your plant.
See www.vacon.com for more information.
www.vacon.com
SEPTEMBER 2008 International Mining 99
Document2 2/9/08 1:27 pm Page 1
DRIVES AND CONTROLS
Testing hydraulic motors at Hägglunds Drives' new,
large hydraulic laboratory
Hydraulic research
when TEFC induction motors are operated at
slow speeds but are still required to provide a
constant torque for industrial applications such
as compressors and conveyor belts. As the
motor speed decreases, the ventilation provided
by the shaft mounted cooling fan also
decreases because the fan speed is reduced.
Manufacturers offered different solutions to
the problem, which increased the cost,
increased the motor dimensions, increased the
nominal power output or reduced the
efficiency and increased the energy
consumption; frequently a combination of
these penalties occurred. The solutions
included external fan installations for forced
ventilation and overpowered/oversized motors
to reduce the temperature rise effects.
Sebastião Nau continued: “There are three
major types of loss which contribute to
temperature rise in TEFC induction motors
under variable speed constant torque
conditions. These may be summarised as the
iron losses (hysteresis and eddy current), Joule
effect losses from the flow of current in the
stator and rotor bars and the mechanical losses
from the friction of rotation of the fan itself.”
If the temperature rise exceeds the motor’s
insulation thermal class, the motor had to be
derated or it would fail. A 10°C rise in motor
operating temperature halves an induction
motor’s useful service life. WEG’s patented
innovations in insulation coating technology –
WISE - were employed to enhance insulation
service lifetime, but the problem has, up to
very recently, proved difficult to solve to
maintain motor efficiency.
The physical law governing induction
(Faraday/ Lenz law) dictates that the magnetic
flux in a motor is directly proportional to the
ratio of electromotive force (V) applied to the
motor and the frequency (f) of the source of
the electromotive power. By reducing the
100 International Mining SEPTEMBER 2008
frequency to reduce motor speed and reducing
the current to keep the flux constant (V/f
ratio), this was an effective and simple way of
maintaining constant torque. Many motor
manufacturers adopted this control strategy.
WEG technologists found that the
conventional control strategy had overlooked
an important variable. This variable is that, at
each operating speed, there is an Optimal
Flux™, which minimises the motor losses while
keeping the torque constant. By calculating the
Optimal Flux for every operating speed, and
programming the frequency converter to
change the flux to the Optimal Flux at every
speed point, the motor losses were minimised
over the entire operating speed range.
WEG’s theoretical modelling of the benefits
of OFT was confirmed by actual trials covering
NEMA High Efficiency, NEMA Premium
Efficiency and IEC Premium Efficiency EFF1
motors from 3.7kW to 110kW; the match
between the modelling and actual
performance under carefully monitored
conditions was close.
Sebastião Nau concluded: “A
comprehensive performance trial was set up
against four major competitors using 3 kW,
four-pole 1,800 rpm motors, over a 1000:1
speed operating range. This, in its turn, clearly
showed that WEG’s Optimal Flux Technology
strategy for WEG NEMA Premium Efficiency,
NEMA High Efficiency and IEC Premium
Efficiency EFF1 motors and motor/CFW-09
drive combination ran significantly cooler than
its competitors.
Optimal Flux technology is also a feature of
WEG’s newly launched CFW11 frequency
inverter series.
In implementing this OFT control strategy
for its highest efficiency TEFC AC induction
motors, WEG offers users high reliability and a
long, low cost life.
One of the world’s largest hydraulic laboratories
is now up and running at Hägglunds Drives’
head office in Mellansel. It covers 1,500 m2 and
has a total installed hydraulic power capacity of
5.5 MW in its 11 test cells. “To assure the
consistent high quality of our products, we need
access to a modern laboratory where we can
test all our hydraulic motors, accessories and
complete systems at an early stage,” explains
laboratory manager Anders Westerlund.
“This investment is an important part of our
continuous development for better and
improved products and drive systems. Our
vision is to improve the productivity for our
customers by using the performance in our
hydraulic drive systems, and with this
extension of the hydraulic laboratory we will
be able to improve the performance even
further." says CEO Per Nordgren.
Hägglunds Drives has just been sold to the
German company Bosch Rexroth. “Together
with Bosch Rexroth we will be able to further
develop our focus on offering complete
hydraulic drive systems in several of our
existing segments. We will also be able to offer
our deliveries of complete hydraulic drive
systems to new interesting segments as
renewable energy production. Combined with
Bosch Rexroth’s strong position on specific
markets where we’re not represented today
we will have a good position for continued
strong growth, says Nordgren.
Sensor support
Hansford Sensors has launched a new range
of ATEX and IEC Ex certified, intrinsically safe
vibration sensors with 4-20 mA outputs, ideal
for direct use with PLC, BMS or other 4-20 mA
input modules. The low cost HS-420I and HS422I sensors are designed for use in online
vibration monitoring applications where the
environment contains inflammable gases,
fumes, chemicals, powders, dust etc. The new
models will allow maintenance engineers to
monitor vibration levels of pumps, fans,
compressors, motors, conveyors, drill rigs and
all types of rotating machinery, which are in a
potentially explosive working environment.
The new HS-420I series of sensors are sealed
to a minimum of IP67 and can be used in both
Group I (Mining) and Group II (Petrochemical)
applications. With their construction in stainless
steel and ability to withstand tough operating
conditions, the sensors offer reliability, optimum
performance and long service. IM
Document2 2/9/08 1:28 pm Page 1
DRIVES AND CONTROLS
Condition monitoring
Shaun Skilton* explains how a proactive approach to
condition monitoring can considerably reduce the cost of
oils and lubricants
T
he old saying about “oiling the wheels of
industry” has always had something of a
double-edged meaning to it. When used
by people from the political or economic
arenas, it all too often implies that injections of
cash can solve almost any problem. Those
involved in the actual oiling of industry’s wheels
and machinery, however, know better.
Maintenance engineers in mining and
processing, are accustomed to having to operate
under increasing pressure to keep equipment
operational. They accept their role is more about
saving money than spending it, and limited
budgets have to be used as cost-efficiently as
possible to help control overall running costs.
One area where more efficient maintenance
procedures can pay dividends in maintaining in
optimum condition the hydraulic oils and
lubricants that help keep a mine’s machinery and
equipment in full working order.
It has been estimated that across industry over
85% of hydraulic system failures can be directly
attributed to contamination of the hydraulic fluid.
Oil lubricants in rotating machinery can also
degrade as a consequence of contamination with
particles and moisture. Although the aggressive
environments found in mining might be a
contributory factor in oil contamination, the
problems of moisture ingress via faulty seals and
gaskets, and contamination with metallic
particles from rotating surfaces and bearing wear,
have been common across industry for years.
As these problems build up gradually, they
inevitably increase operating costs as loss of
lubrication leads to higher levels of wear in
bearings and shafts, with increased power and
fuel consumption. Water ingress into oil can result
in bacterial and fungal growth that affects its
properties and produces damaging acid corrosion
and oxidation of bearing surfaces and rubber seals.
The earliest solution to these long-term
problems used to be simple reactive
maintenance; when contaminant build-up
brought the system to a grinding halt, the oil
was changed and, inevitably, repairs were carried
out on the equipment. Anathema to today’s
maintenance engineers, this crude and expensive
approach was soon replaced by proactive
maintenance, in which oils and lubricants would
be changed on a more or less rigidly controlled
schedule of programmed maintenance. While
this methodology is better at minimising
equipment downtime, it can prove wasteful if
contamination has not yet reached damaging
levels. And replacement with new oils and
disposal of the old by approved contractors is an
increasingly costly option.
Rather than replace oils and
lubricants, current thinking
now revolves
around
predictive
maintenance, with the
goal of extending an oil’s
operating life by use of
relatively low cost condition
monitoring equipment, allied
to a more practical approach to
the replacement of filter
elements. Unlike the expensive
systems needed to monitor the
performance of capital equipment such as
high-speed generators and compressors, with
their accelerometers and vibration analysis tools,
oil condition monitoring involves simply the
detection of particles and moisture. These are
tasks that can be performed quickly and
accurately, with a range of instruments suitable
for either off-line testing or fully integrated into
the oil lines to give a continuous indication of the
oil’s condition.
Solid particle detection by instruments such as
Parker’s LaserCM and the new IcountPD
generally involves a laser-based operation in
which a beam of light is passed through the oil.
As particles pass the photo diode sampling
point, the reduction in light intensity transmitted,
which is proportional to the particle size, is
measured and recorded. Data can then be
downloaded into trend analysis software that
enables quite subtle deteriorating changes in a
fluid’s condition to be picked up and acted upon
before any abnormal wear becomes a problem.
Although they can be connected dynamically
in-line, instruments like the LaserCM and Parker’s
H2Oil water-in-oil monitor are essentially
portable instruments complete with handheld
data capture and LCD display units. With test
cycle times as little as two minutes, these lend
themselves to predictive maintenance programs.
The IcountPD particle detector, on the other
hand, is designed to be integrated into the oil
lines as a permanent, intelligent device that gives
a continuous indication of the oil’s condition.
Another laser diode based instrument, this small,
low cost unit can be built into equipment by
OEMs, or easily retrofitted in the same way as
other in-line instruments. Immediate display of
oil condition is via a simple LED readout giving a
continuous indication of particle and moisture
content, with early warning indicators for Low,
Medium or High contamination levels.
The moisture sensor, with a reporting range
between 5% and 100% saturation, is an option
that can be included in the initial specification. The
particle display parameters conform to the ISO
4406:1999 method for coding the level of
contamination of hydraulic fluids by solid particles.
In addition to its integral
display unit, the IcountPD
features full communications
capability with RS232, 0-5V
and 4-20mA AND CANBUS J1939
outputs, opening up the possibility of
remote, even off-site, condition monitoring
of oil and hydraulic systems.
Solid particle detection by instruments such
as Parker's new IcountPD generally
involves a laser-based operation in which a
beam of light is passed through the oil
Compared with the proactive maintenance
approach of testing oils according to a
preordained schedule, these
instruments all perform a predictive role by
identifying a potential problem, that is, the
presence of particle contamination or moisture
in oil, before it has the chance to become a
major problem, requiring either complete oil
changes or, at worse, repairing damaged
equipment.
Identified early enough, contamination can be
removed by filtration. This assumes, of course,
that the equipment’s filter units are themselves
efficiently maintained. All too often, filter
elements fall foul of the scheduled maintenance
approach; changed at fixed time intervals, with
little consideration being given to the likely fall
off in their efficiency with prolonged use.
A partially blocked filter may still remove some
contamination, but it will be at the expense of
reduced oil circulation, increased pumping costs
and a continuing build-up of contamination.
Once contamination is detected in an oil line
by a condition monitoring system, the first thing
to look at therefore is the condition of the filter
units. After all, replacing a filter element is a far
cheaper option then having to replace a machine’s
entire oil or hydraulic fluid inventory. IM
*Condition Monitoring Product Sales Manager
for Parker Hannifin.
SEPTEMBER 2008 International Mining 101