TABLE OF CONTENTS The development of a condition-monitoring system involves the measurement of operating variables of the plant being monitored, and interpretation as well as management of the acquired data. In many plants, measurements are already used for control and protection objectives. From a cost point of view, it would be ideal if such measurements could also be used for condition monitoring. However, knowledge of the limitations of the existing measurements and understanding of the difference between the objectives of control, protection and condition monitoring is important, as will be seen later in the book.
One feature of condition monitoring, described in Chapter 3, is to detect impeding faults at an early stage, capturing weak signatures in measurements that are usually mixed with noise. Furthermore, some impeding faults may manifest themselves in non-electrical variables that are not normally used in control or protection. Before getting into the details of the instrumentation elements, we need to view a condition-monitoring system from a higher level where the functionality of different parts of the system can be more clearly described. By doing this, it should be possible to identify the common elements of a condition-monitoring scheme, irrespective of the system detail. In essence we are saying that an engineer examining occasional meter readings, with a view to producing an operational and maintenance strategy, is involved in a procedure that is analogous to a sophisticated condition-monitoring system.
In view of this analogy, we believe that the following tasks are essential elements in a condition-monitoring system...
