Condition monitoring assures a cost effective way of substantially reducing breakdown risks
September 1st 2008 For every manufacturing organisation, breakdowns are a major concern. Not
only can they be costly to remedy, they also result in lost production and
disappointed customers. Fortunately, there is a convenient and cost-effective
way of substantially reducing breakdown risk, says Ian Smith technical
manager of ERIKS Electro-Mechanical Services
Spend a little money on a regular
basis and virtually eliminate the risk
of equipment failures and
breakdowns, the total costs of which can
in many cases run into tens, if not
hundreds of thousands of pounds. That
may sound too good to be true, but it's
precisely what well-implemented condition
monitoring has to offer.
Essential features of the techniques
used in condition monitoring are that they
can be employed without the need to shut
down the machine that is being monitored.
Indeed, most of the techniques rely upon
the equipment being in operation while the
tests are carried out. In addition, the main
techniques are non-invasive, so they will
not adversely affect the operation of the
equipment in any way.
The forces that produce vibrations are
associated with a wide range of types of
machine components, each of which
usually has its own associated frequency.
These so-called forcing frequencies may,
for example, relate to rotational shaft
speeds, gear meshing, bearing vibrations,
oil whirl in plain bearing
machines and random
vibrations.
Analysis of the data
obtained from the
vibration
transducer can,
therefore, be used to give a good
indication of its source and, if there is a
sudden change in frequency or amplitude,
where the investigations into the cause of
the change should be focused.
Closely allied to vibration analysis are
modern methods for addressing the
problems it reveals. These include
laser alignment and on-site
balancing of rotating components.
Laser alignment is principally used
to correct misaligned couplings,
and greatly reduces the risk of
damage to bearings and seals, as
well as minimising energy losses.
On-site balancing ensures that
machines run smoothly, prolonging
their useful life and, once again,
reducing power consumption.
Another technique that is starting
to be very widely used is
thermography – essential looking
at images of the equipment that
are coloured to show the relative
temperatures of the components
and, in particular, reveal hot spots.
This can be useful, for example, to
reveal a bearing that's running hot,
or other areas where there is
excessive friction in a machine.
Another condition monitoring
technique with a very wide range
of applications is oil analysis, which
is applicable to both mechanical and
electrical equipment. Lubrication oils
are typically tested for moisture,
viscosity change,
contamination and
component wear
particles – the
excessive
presence of
which
can
signify a
component
approaching
failure.
Specific condition
monitoring tests for
electrical equipment are many and varied,
but among the most useful are insulation
tests, especially for high-voltage
equipment, where a decline in insulation
resistance, even though its current value
may still be well within acceptable limits, is
a dependable sign that attention is
needed.
An innovative and very effective
approach to evaluating the condition of the
insulation in high voltage motors and
generators is partial discharge testing
using Rogowski coil technology. This is a
completely non-invasive technique that,
unlike many of the alternatives, does not
stress the insulation. Nevertheless, it yields
accurate and reliable results.
Condition monitoring is arguably the
best investment a manufacturing company
can make in minimising the risk of needing
costly plant repairs, and of losing money
and customer goodwill because of
downtime. Particularly when the condition
monitoring service is provided by an
expert contractor, the costs are small but
the potential benefits are enormous. More articles from ERIKS UK: | 
