Reliability Analysis of Smart Pressure Transmitter

Abstract

In recent years, the advent of technology has necessitated the use of ‘smart’ transmitters. A transmitter is described as ‘smart’ if it incorporates signal conditioning and processing functions that are carried out by embedded microprocessors. Smart transmitters generally have the features like self-diagnosis, fault detection, digital communication, etc. However, with the advancement in the features and capabilities, the complexity of the smart transmitter has increased and also the estimation of its reliability. In this paper, we have carried out reliability analysis of a smart pressure transmitter. Incorporation of the smart features requires use of many electronic items/components. These components of the system may or may not fail independently, and their failure may lead to unavailability or degraded performance of the system. This has been modelled using the goal tree (GT) and success tree (ST) methodology. GT defines system objective which is a set of functions that shall be fulfilled to achieve the goal. Success tree ST defines the structure of the system and comprises system components used to achieve the GT functions. The system performance is considered as a function of its components. The interdependency between the system performance and its components is modelled using the Master Logic Diagram (MLD) wherein the potential faults/failures are introduced into the system. Nine potential faults/failure modes were identified, and their impact on the system capability to perform was studied. The cause and effect relationship captured using the MLD is then translated into the mathematical model. The evaluation of this model is carried out using fault tree, which provides an estimate of the unavailability of the system. The unavailability of the system for a mission time of one year has been found to be 4.617E−2.