Pdf basics of electricity12/6/2023 ![]() Realization of this objective will result in enhancing availability, reliability and reduction in manpower for maintenance purposes. To meet this aim we have to develop equipment which require either no or very little maintenance and on the other hand the concept of condition based maintenance should be implemented. ![]() From the view point of RCM our objective should be to devise a system, which does not need periodic maintenance and at the same time predict in advance possible failures/problems of the equipment. 1 Reliability centered maintenance policy is based on the life cycle cost concept and the decision for replacement of the equipment is taken based on techno-economic considerations. The basic objectives of reliability-centered maintenance are:-Maintenance should keep the equipment at desired level of performance-Optimizing / minimizing the maintenance / shutdown period so as to enhance the availability of the equipment.-Deferring / avoiding the replacement of components and major/minor overhauls till it is absolutely necessary. iv) Reliability Centered Maintenance This is the recent technique being adopted in maintenance philosophy. However, this type of maintenance would need sophisticated testing equipments and skills for analyzing the test results. Some of the tests are done on on-line and some are done on off-line. The condition of the equipment is assessed based on different condition monitoring tests. iii) Condition Based Monitoring This type of maintenance technique is adopted to assess the condition of the equipment. Maintenance procedure, periodicity of maintenance and formats for maintaining records for various types of sub-station equipments have been discussed separately in detail in a separate section. This type of maintenance would require specific period of shutdown. The frequency determined based on the past experience and also guidance from the manufacturer of the equipment. In this type of maintenance, the equipments are inspected at a predetermined period. ![]() ii) Preventive Maintenance The preventive maintenance of equipment is being mostly adopted by almost all the utilities. ![]() Therefore identifying the defect before failure, is more appropriate to plan repair / replacement. The revenue loss due to non-availability of the system shall be much more than the cost of the failed equipment. However for costly substation equipments, it is not desirable to wait till the breakdown of the equipment, as this cost more to the utility as well as the availability and reliability of power gets affected. This type of maintenance may be appropriate for low value items. 2.0 TYPES OF MAINTENANCE Different types of maintenance being done on equipment are: i) Breakdown maintenance ii) Preventive maintenance iii) Condition based monitoring iv) Reliability centered maintenance i) Breakdown Maintenance As the name implies the maintenance is carried out when the equipment fails. However, tests or measurements are also carried out to assess the condition of the equipment. Maintenance intervals are normally fixed on the basis of type of equipment and sometimes on the equipment history. This has led the utilities to adopt condition-based maintenance of the equipments rather than usual preventive maintenance being carried out at a fixed interval of time. 1.0-INTRODUCTION 1.1 In today's competitive market scenario power utilities are under tremendous pressure to cut down their maintenance costs as they form a significant portion of the operation costs.
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