At present, most maintenance activities are carried out by the preventive or
the breakdown maintenance approach. The former suffers from occasional
over maintenance (or under maintenance) and the
latter suffers from system outages because of breakdown and time taken for the repair work. Predictive maintenance or
Condition-Based Maintenance (CBM) differs from preventive maintenance
as it fixes the maintenance need on the actual condition of the machine rather than on some
preset schedule. In other words, CBM is a set of maintenance activities based on
real-time assessment of equipment condition, which is obtained from embedded sensors
and/or external measurements taken by portable sensing equipments. A comprehensive
CBM-based predictive maintenance strategy can be based on a combination of
a number of CBM tools, like thermal imaging, vibration monitoring or other non-destructive
sensing methods, to obtain the actual operating condition of
a critical plant component.
With the advent of new technologies, a number of new condition monitoring
techniques have come up for the electrical equipments, such as motor, alternator and
transformers. The following sections give a brief introduction to
various condition monitoring techniques.
Temperature Measurement: Temperature measurement (for example,
temperature indicating paint, thermography, pyrometer for measuring the emitted IR radiations from
a surface, etc.) can detect potential failures related to temperature changes in an
equipment. Temperature changes can indicate conditions such as excess mechanical friction due
to faulty bearings or inadequate lubrication, and degraded heat transfer at poor
electrical connections like loose or corroded connections.
Dynamic Monitoring: Dynamic monitoring (for example, spectrum analysis, shock
pulse analysis, etc.) measures and analyzes energy emitted from mechanical equipments in
the form of vibrations, pulses or acoustic effects, as the changes in the vibration
characteristics of equipment can indicate problems such as misalignment, damage, imbalance, and
wear and tear. |
