FEATURE DRIVES, CONTROLS & MOTORS
MOTORING ON I
f a motor fails, most companies will need their processes back up and
running as quickly as possible. But should the motor simply be replaced with a new version or can a motor repair or rewind be carried out on the old one? This isn’t a decision that should be taken lightly. A new motor offering higher efficiency can come at a greater cost, but there may be concerns about the potential inefficiencies that an electric motor rewind can bring. According to some studies, a rewind can drop efficiency by between 1% and 5%. Considering the associated expense and sheer volume of energy these motors use, this is naturally concerning. However, EASA and AEMT, in association with Nottingham University, carried out tests on 22 new motors that ranged from 50 to 300hp. Overall, the results found that when electric motors were rewound using good practice, there was no significant change in their efficiency – in fact, in some instances, it actually increased. This clearly dispels the belief that a rewind is actually detrimental to a motor’s performance.
ASK THE QUESTION As a result, it is important to fully evaluate the options to make sure you make the right choice in terms of operation, cost
and efficiency. This can be done by asking a number of key questions.
Is the motor suitable? Operational needs can change, so an electric motor that was once suitable may no longer be so. Review the scale of the damage alongside the requirements for the motor’s processes and duty cycles. If the motor is no longer suitable or too damaged, it will need to be replaced. If the motor is still suitable for the
application, check the stator core and rotor. If significant damage is present, it may be more beneficial to purchase a new motor as, depending on the extent of the damage, repairs can be costly. However, if the lead times for the new motor are long, downtime may be reduced by repairing it.
Have other mechanical parts been damaged? When motor failure occurs, it is possible that damage may occur to the shaft, frame, bearing housing and other mechanical parts. Examine the extent of the damage – it may be possible to replace the affected parts at a lower cost than replacing the entire motor.
Is it an EPAct or Nema Premium motor? If the motor has failed, it may be an
NEW RANGE OF GEARED MOTORS FOR APPLICATIONS IN HEAVY INDUSTRIES
New to WEG’s WG20 family of geared motors are helical, parallel- shaft and helical bevel gear units. Combining high performance in a compact design, these are for torques up to 4500Nm. These can be combined with WEG modular motors with
power ratings from 120W to 30kW. This combination provides geared motors with energy efficiency ratings up to IE4, suitable for operation directly from the AC line. The housings are fabricated in a single monobloc design
from grey cast iron which gives them high torsional stiffness. In addition, they can be manufactured to very tight tolerances and their smooth surface means they can be used in applications that require a stringent cleaning regime. The smart, modular, pinion allows the gear units to be implemented in two-stage or three-stage designs over a wide range of gear ratios, resulting in very low losses and making the gear units very energy efficient. The variant-optimised tooth concept also enables high output shaft speeds and operation over a large speed range. These are suitable
for demanding applications within heavy industries such as steel mills.
WEG (UK) 22 MAY 2018 | DESIGN SOLUTIONS
www.weg.net
When motor failure occurs, it is possible that damage may occur to the shaft, frame, bearing housing and other mechanical parts
opportunity to specify a more efficient model. Here, it will be important to consider the energy savings alongside the expected life of the motor and its hours of operation. The overall budget needs to be considered here too, to make sure the replacement aligns with your current financial position.
Houghton International T: 0191 234 3000
www.houghton-international.com
A ROBUST MOTOR FOR HARSH CONDITIONS
Parvalux has introduced the compact yet robust VIPER 3, a windscreen wiper motor for applications in transportation sectors such as rail, marine and haulage. The geared motors are available in two options – the 80 and 110 series (breakaway torque 80Nm and 110Nm), with two speeds for both options of 21/36rpm or 30/45rpm. They provide clockwise or counter clockwise direction. Capable of withstanding the harshest conditions including dust, liquids, extreme temperatures and humidity, these have protection from IP42 to IP56. They are also equipped with multiple mounting options and added support structures for reliability and quick integration into systems, while the large brush design reduces wear on the brushes in higher speed modes.
Parvalux
www.parvalux.com DRUM MOTOR PERFORMANCE INCREASED
Rulmeca has increased the nominal output performance of its 80LS drum motors, within an 81.5mm diameter roller, from a maximum of 120 watts to a maximum of 160 watts. The 33% percent performance increase was achieved through the redesign of the stator. The shortest available width of the new drum motor is 300mm. In addition,
this compact motorised drum with steel gearbox is reversible so is said to be ideal for high torque applications with limited space or access.
Rulmeca
www.rulmeca.com
The failure of a motor can have a huge impact on productivity, but
what’s the best option: to repair it or replace it with a new, higher
efficiency, model? Michael Mitten, CEO of Houghton International, discusses the options
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