RAMS AND ENGINEERING
Engineering is the art of finding an optimal combination of all RAMS factors in order to create a balanced product. But what is RAMS?
RAMS stands for Reliability, Availability Maintainability, Safety.
• Reliability: Quality of a product
• Availability: Probability that the product is operating at a specified time
• Maintainability: Ability of something to be retainedin or restored to an operational state
• Safety: Ability of the product not to cause injury to persons, nor significant material damage, etc.
In order to make a balanced product we must take into consideration the Safety, Dependence and Reliability of the product on the required function, environment, etc.
There are 4 types of reliability:
• Theoretical reliability
• Structural reliability
• Reliability of electromechanical and electronic parts.
All this is important because on this will depend the customer satisfaction and company reputation.
RAMS ANALYSIS: Random Failures
A random failure is a failure which happen when stress peaks overlaps the strength peaks in the components.
People has always attempted to make components and systems that arereliable and durable but there has allways been errors due to the human presence in the proces. Because the complexity of the components and systems have been increasing and the production time has decreased with the time, the testing for possible failures have became more important on the industries.
This testing is what we call the RAMS analysis.
ESSENTIAL COMPONENTS OF CCPP, ROLE OF DCS
APower Plant is a system that produces energy. Each kind of Power plant has its key components. For example in a steam power plant, the key components are: Steamer, Cooler, Generator, and Steam Turbine. In a Combined Cycle Power Plant (CCPP), the main components are: Boiler, Steam Turbine, Gas Turbine, Generator (1 and 2), Heat Exchanger, Energy Distribution System and Pump. In this kind of powerplant the efficiency increases from 30% to 50%. In order to achieve this, a Digital Control System (DCS) becomes the most important part of the plant, this is because DCS is the “brain” of the Power Plant and without it the Plant doesn’t works anymore.
The function of a DCS is to control a system by sampling a feedback from the system and modifying the signals in order to make it work as desired.
RAMS ANALYSIS TECHNIQUES: TOP-DOWN, RBD AND FT
A Top Down approach is used when a company wants to improve the overall reliability when they don’t know why the problems occur. With this method is possible to reduce the uncertainty in the predictions by mainly relying on the failure data history of the unit design with verified field performances.
A Reliability Block Diagram is a visualrepresentation of a system’s reliability performance. It shows the logical connection of the components needed for the system success. Its main objective is to find the survival logic of the system.
With an RBD is possible to find the critical component of a system and look for the best solution (replacement or improve).
The advantages of RBD are:
• Helps to understand the system
• Helps to findpotential bottle necks
• Qualitative and quantitative analysis can be done
The disadvantages are:
• Not useful in dynamic processes (hard for time-dependent processes)
A Fault tree (FT) is an organized visual representation of factors causing or contributing to an outcome (top event). When the outcome is a success, then the fault tree becomes a success tree where the factors involved are thetop success of the event.
The main objective or a FT is to find failure or success logic for the system.
The advantages of FT are:
• Can be derived from RBD (in most of the cases)
• Recognize weakness areas of the system (bottle necks)
• Helps to understand the relation between the components of the system
The disadvantages are:
• Not useful in dynamic processes
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