PREVENTIVE MAINTENANCE
required work for times when it will cause
least disruption.
“Furthermore, it can be possible to
leverage knowledge about the health of
a motor to adjust the way it’s used, such
as by reducing its load so that it might be
‘nursed’ to the next scheduled downtime,”
explains Wright, who goes on to suggest
that performing a root cause analysis is
always advisable in case an issue is found.
“For example, if the fault resulted
from an imbalance in the fan or poorquality
bearings, it will keep recurring,” he
states. “A partner with service expertise
is essential to make e ective use of the
condition data collected, so it can advise
if a repair or upgrade is appropriate,
or if replacement might be
the most cost-e ective
approach.”
Jason
Tweedy, head
Brammer Buck
& Hickman says
specialist motor
checks should
take place every
three months
of condition monitoring - UK at Brammer
Buck & Hickman, says that the best
inspections are audible and visual checks
while the motor is running. He adds: “The
persons best suited to conducing these
inspections are the on-site operations
engineers, who know their equipment
better than anyone else and will therefore
be aware of a slight change in noise or
movement, giving them the ability to
action an appropriate response,” he says.
Tweedy adds that further checks are
possible when the motor is isolated,
which will be speci c to certain types
of motor: inspecting brushes on DC
motors, checking lubrication and ensuring
there is no damage to couplings, for
example. Also, checking for
an excessively or unusually
hot motor is important as
overheating is one of the main
reasons for motor failure.
“Ideally, routine checks
should be performed daily,”
he says. “Specialist checks,
like greasing and brush
inspection, will depend on the
motor, its size, running hours
and operating environment,
but as an approximate guide, every
three months would be suitable.”
In terms of tools, Tweedy recommends
an o -the-shelf thermal camera as a
good place to start. “Thermal cameras
are relatively inexpensive and can provide
useful information if used regularly to
inspect motors,” he explains. Grease guns
or specialist lubrication can help extend
bearing life, he adds.
According to Brammer Buck &
Hickman, most motors fail due to
incorrect installation or use; for example,
a misaligned motor or shock load to
the transmission. “If issues such as
misalignment or lack of lubrication are
found, act immediately,” concludes
Tweedy. “If you’re unsure what to do,
contact an expert. Motors are the work
horses of virtually all plants. If they stop,
your business stops.”
In the event of a motor
issue, ABB always advices
a root cause analysis
Rotamec says most
motor checks can be
made using a insulation
tester, multimeter and
vibration analyser
LISTEN UP
According to John Drew, site
services support manager at
electromechanical services provider
Rotomec, “listening for unusual
noises at either end of the motor
could be an indication of bearing
failure. Here, the motor would require
removal for inspection at the earliest
possible convenience to avoid a
catastrophic failure, which could
potentially write it o . Furthermore,
while not all motors have bearing
grease points, it’s important to use
the same grease throughout the
life of the motor and/or bearing.
Mixing grease grades or types can
lead to premature bearing failure, as
the grease will harden and not mix
correctly in the housing.”
Drew is keen to point out that
while most of these checks can take
place during motor operation, it is
best to do them at time when turning
o the motor is possible, if required.
“Most checks can be made with
a good quality
insulation tester,
multimeter and
vibration analyser,” he
says. “Common issues we
see include belt-driven fans with
motor bearing failure, where the
likely cause is incorrect tensioning of
the belts and/or misalignment of the
drive pulleys. We also sometimes see
new motors that have burnt out their
windings almost immediately after
tting. It’s so important to check
and test the control gear prior to
installing a new motor.
“There are reasons behind any
failure,” continues Drew. “It’s easy
to address the failure but also easy
to overlook the root cause. That’s
why regular maintenance is essential,
where using an experienced
electromechanical services provider
will help to keep consistency of
service and o er the best protection
against premature failure.”
Winter 2021 www.operationsengineer.org.uk 57
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