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| [Servos] [Machines & Drives] [On-site Services] [Mechanical Repairs] [Electrical Manufacturing] [Equipment Overhaul] [Electronics] [Engineering] [Calibration] [Asset Management] |
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Large machine services from Dowding & Mills - market leaders
in Engineering, Calibration & Electronics. Large electrical rotating machines and transformers are, by their very nature, critical to any companys operation and, in addition, represent a substantial capital investment. Dowding & Mills recognises the importance of these machines to
its customers and provides well-equipped facilities with experienced
engineers who are highly qualified to industry standards, in motor rewinds
and generator repairs. Consultancy A global Technical Services team enables the total management of major refurbishment projects and the re-design of machines to up grade and improve efficiency.
"In-house" computer programmes are available to enable the complete re-design of large salient pole generators, together with the associated winding re-design. Site surveys can be arranged to ascertain the potential benefits to
be gained from the Enhance Capital Allowances, as part of the Climate
Change Levy, and the installation of energy efficient equipment.
The scope of motor rewinds and generator repairs
cover fractional horsepower single phase motors to multi-megawatt
AC machines with squirrel cage rotors, wound rotors with slip
rings or commutators, salient pole rotors and cylindrical turbo
types. In addition, the service covers DC
motor rewinds up to those used for hot mill roller drives in Steelworks,
as well as the more unconventional machines such as frequency
changer's, linear motors, liquid metal pump motors and stirrers.
Transformer repairs and oil testing up to 10 MVA 33kV are also
within the capability of Dowding & Mills. Repair Facilities
Dowding & Mills workshops have been designed to provide motor rewinds
and generator repairs to industry and are amongst the most modern and
well-equipped in the world. To support its motor rewinds and generator repairs service, Dowding
& Mills has the most advanced coil manufacturing facility (with
its own copper mill) to be found in the repair industry, which together
with in-house commutator manufacturing, provides a service capability
second to none.
The failure of a machine is normally the end result
of progressive degradation, which may take months or years to
develop. Identifying potential problems before failure, by condition
monitoring, is an important factor for plant engineers in reducing
unscheduled downtime and maximising plant availability. The most frequently used condition monitoring tools are vibration analysers,
thermographic cameras, insulation diagnostic instruments, rotor condition
measurement instruments and visual examination. Stator Monitor ® analyses the high frequency disturbances
in phase current, caused during partial discharge events, to evaluate
the condition of the stator winding insulation. Dowding & Mills Field Operations provides a comprehensive project
management service to customers world-wide, particularly in Power Generation,
Mining, Docks and Heavy Industrial environments.
It handles minor contracts to major projects, which can include wholesale
refurbishments and upgrades on the re-siting of mine-winder gear and
generator systems.
Engineering Support Design Support For instance, HV machines can be re-designed using coils with improved
insulation materials or a new stator core manufactured from modern low-loss
materials and new slot geometry. Modern materials can very often be
used in the re-design of a gearbox or transmission system to improve
its overall performance and life
Dowding & Mills’ on-site services range includes motor rewinds
and generator repairs. When a machine is too large or uneconomical to
remove from location a repair or full rewind can be carried out insitu,
without compromising on quality. As part of a motor rewind or generator repair,
Dowding & Mills engineers will dismantle the machine and record
a full set of data from the existing windings. While the old windings
are being removed, the new coils are produced at the company’s
coil manufacturing facility. Using a unique in-house CAD system,
engineers can redesign the coils taking into account operational
parameters and modern insulation systems, which helps to improve
efficiency and extend life. Once the windings have been removed the core
is visually inspected, cleaned, and a core flux test is then carried
out to ensure there has been no physical or electrical damage.
A full range of tests are then carried out, including high voltage
proof test and diagnostic testing, which will establish a footprint
of the machine’s parameters, for comparison in any future condition
monitoring schedules. The machine is then assembled test run and commissioned by our own
engineers.
Turbine Services, part of Dowding & Mills Engineering Services,
is able to carry out a wide range of repairs on components within the
steam or gas path of turbines.
These repairs cover an extensive range of component salvage operations,
including the reinstatement of rotating blade tips and leading edge
material losses due to field object damage, corrosion/erosion and water
droplet erosion.
On first stage nozzles and diaphragms, the most severely damaged vanes
and sidewall areas can be re-instated, by either weld build up and re-machining,
or by replacing sections of the component with new material, spill strip
replacement and by reverse engineering new components.
The full scope of these services is available to turbine operators,
in the U.S.A., Canada, Australia and Europe, through the worldwide network
of workshops whose managers would be pleased to discuss individual requirements.
Diaphragms & nozzles
Working to internationally approved standards, Dowding & Mills
offers a range of repairs to cover even the most extensive damage to
diaphragms and nozzles.
Vanes and sidewall areas damaged through erosion or the intrusion
of foreign objects can be rebuilt or repaired. This can involve
partial or complete vane replacement or repair welding, using
either parent or improved specification materials. Original dimensions are then re-established using the extensive
machining facilities available throughout the Group. Inspection
procedures and supporting documentation fully comply with ISO
9002
Rotating blades
The service includes a comprehensive range of rotor blade repairs,
which are carried out by experienced and internationally approved engineers
and encompasses leading edge material replacement, tip and tenon repairs.
All work is covered by a Pre-Submitted Workscope and NDT procedures,
which are to the accepted turbine industry standards.
For operators, Dowding & Mills carries out turbo generator repairs
for rotors and stators, for machines up to 300MW machines.
The service and repair of main and pilot exciters,
as well as the replacement of end rings is also undertaken for
machines of any mega watt rating
This service includes on and off line condition monitoring, fault
investigations and machine inspections. In addition, through the
design facility within the Engineering Support team, a machine
can be up graded to give greater efficiency and extended life.
Supporting the generator repair function is Dowding & Mills Technical
Services, which manages complete refurbishment projects from planning
through to commissioning and the high voltage coil manufacturing facility,
which provides copper and finished coils for this type of work.
Dowding & Mills’
state-of-the art balancing and overspeed facility makes it the
only UK independent, generator repairer to offer a complete, in-house,
refurbishment programme.
Dowding & Mills - Engineering,
Calibration
& Electronics Services
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