Showing papers on "Condition monitoring published in 1980"

Application of Vibration Signal Analysis Techniques to Condition Monitoring

Abstract: Analysis of vibration signals is a major technique for monitoring condition of machine components. Frequency spectrum analysis is the most widely used method. Various other methods, which have advantages in particular circumstances, are described and some bearing test results given.

Signature monitoring of nuclear power plant dynamics - Stochastic modeling and case studies

Abstract: The increasing emphasis on the operational safety of nuclear power reactors necessitates the development of improved on-line and off-line monitoring methods during the normal plant operation. The random fluctuations in the neutron power and other system variables can be processed to extract information about sensor integrity, detection of anomalous conditions, estimation of stability margin, trend analysis, and incipient failure detection. This paper presents some of the recent developments in the areas of multivariate time series modeling and dynamic stochastic modeling with applications to both pressurized water reactors (PWRs) and boiling water reactors (BWRs). Three case studies - sensor fault detection using analytic redundancy, reactor diagnostics using multivariate spectral decomposition, and time dependent parameter estimation of BWR stability margin and steam velocity are discussed.

Maintenance strategies affecting equipment performance

Abstract: Proper maintenance of plant items is crucial for the safe and profitable operation of process plants, The relevant maintenance policies fall into the following four categories: (i) preventivejopportunistic/breakdown replacement policies, (ii) inspection/inspection-repair-replacernent policies, (iii) restorative maintenance policies, and (iv) condition based maintenance policies, For correlating failure times of component equipnent and complete systems, the Weibull failure distribution has been used, A new powerful method, SEQLIM, has been proposed for the estimation of the Weibull parameters; particularly, when maintenance records contain very few failures and many successful operation times. When a system consists of a number of replaceable, ageing components, an opporturistic replacernent policy has been found to be cost-effective, A simple opportunistic rrodel has been developed. Inspection models with various objective functions have been investigated, It was found that, on the assumption of a negative exponential failure distribution, all models converge to the same optimal inspection interval; provided the safety components are very reliable and the demand rate is low, When deterioration becomes a contributory factor to same failures, periodic inspections, calculated from above models, are too frequent, A case of safety trip systems has been studied, A highly effective restorative maintenance policy can be developed if the performance of the equipment under this category can be related to some predictive modelling. A novel fouling model has been proposed to determine cleaning strategies of condensers, Condition-based maintenance policies have been investigated. A simple gauge has been designed for condition monitoring of relief valve springs. A typical case of an exothermic inert gas generation plant has been studied, to demonstrate how various policies can be applied to devise overall maintenance actions.