Preventive Maintenance Process Research Articles

Failure mapping and critical measurements for the operating condition assessment of power transformers

The causes of failure of critical component of the electrical power distribution network like the power transformers, has always attracted the interest of the scientific and technical community, since the failures of electrical transformers almost always have a great impact on the consumers, as they can lead to a black out situation. A reliable and coherent maintenance schedule, that would predict the causes and prevent un-expectable shutdowns of power transformers, is of outmost importance nowadays, since electrification is expanding in terms of volume and power, as well as in terms of production sources, voltage and location. Such a reliable and coherent maintenance schedule depends on many factors and this article describes the parts of oil-immersed power transformers that are prone to failure. It also illustrates the relationship of the well known dissolved gasses that appear in the insulating oil as a result of specific operating faults, with specific measurements that should be done periodically, in order to prevent a major failure. Additionally, it describes the relationship between these dissolved gases with specific maintenance actions that should be implemented during the preventive maintenance process.

A Method for Safety Evaluation of Train Braking System Considering Multiple Types of Preventive Maintenance Cycles

The train braking system with redundant components has an essential effect on driver safety. In this paper, we consider the failure of K-out-of-N brake motors during operation and the redundant recovery by preventive maintenance. Two Continuous Time Markov Chains (CTMC) are used to model the working process and the preventive maintenance process of the braking system corresponding to the real situation of the train. Considering the maintenance effect of intermittent daily and cyclical overhaul with nested relationships, a new operation risk assessment model of the K-out-of-N system is developed to evaluate the effectiveness of the preventive maintenance of the train. Some safety parameters are solved based on the two coupled preventive maintenance periods, which conveniently design the safety of the train braking system. Finally, a case study illustrates the effectiveness of the safety evaluation method. The results show that we can trade off the effects of the multiple PM intervals on train safety considering the redundancy structure of the braking system by the proposed model.

Recommendations for Refined Preventive Maintenance Management of Concrete Bridges in China Based on Environmental Risk Zoning

Service environment has an important influence on the durability of concrete bridges. Environmental factors are often considered in the design stage, however, they tend to be ignored in the process of maintenance management. It is of great significance in prolonging the service life of a bridge to pay attention to the influence of the environment on the deterioration of the bridge during the preventive maintenance process. Concrete carbonation, chloride ion corrosion, sulfate corrosion, concrete cracking, concrete abrasion, and freeze–thaw damage are the main causes of decline of bridge durability. Based on these six kinds of distress, indexes of environmental zoning are proposed. For this purpose, variable weight theory is introduced into the matter-element extension model, and the comprehensive environmental risk values of various regions are calculated. The environmental risk zoning map of the concrete bridge’s location is then drawn using data visualization software (Tubiaoxiu). These maps show that the east, south, and southwest of China are the most high-risk areas for the deterioration of concrete bridges, and the validity of the results is proved by the distribution of collected bridge collapse accidents. Through the environmental risk zoning map, managers can intuitively grasp the degree of environmental risk in each region in real time. This approach could help bridge management department to implement differential management of concrete bridges in different regions, adjust bridge maintenance intervals dynamically, predict the state of bridges scientifically, and realize refined preventive maintenance management.

Stochastic Model for Integrated Preventive Maintenance Planning

Preventive maintenance planning management is modelled with stochastic approach. It is aimed to prevent stoppages and quality disorders due to disturbances, carriage and maintenance processes in production. Different maintenance policy alternatives were considered in order to develop and sustain more effective maintenance policies. The preventive maintenance process includes the cost of inspection and maintenance status, the cost of repair and other losses in the accidents with operator injuries and damage to the possible value of the situation. The stochastic model approach is applied for determine the possible period intervals of the machinery and equipment and the maintenance process analyzed and discussed in detail. The preventive maintenance approach in the maintenance planning process is aimed to develop a sustainable maintenance policy without any disturbance in the quality of production from any disturbance and disruption of the system in the long term. However, it is aimed to take preventive maintenance measures as well as to analyze the current system condition and predict future situations.

PENERAPAN ALGORITMA ROUND ROBIN PADA PENJADWALAN PREVENTIVE MAINTENANCE DI PT. PASIFIK SATELIT NUSANTARA

Scheduling is needed when several activities must be processed at a certain time. Good scheduling maximizes the effectiveness of the use of every activity, so scheduling is an important part of planning and controlling activities. At PT. Pasifik Satelit Nusantara, there are maintenance activities on the devices used by the preventive maintenance process customers needed so that no additional costs occur, so it needs to be done scheduling that can minimize downtime. For this reason, the schedule must be in accordance with the actual conditions in the company so as to minimize downtime so that the process of customer activity is not hampered by damaged equipment. In this study utilizing a round robin algorithm that can schedule human resources that carry out preventife maintenance activities. The author uses website-based media so that it can easily be used by company superiors to schedule technicians or workers.

Discussion about the maintenance period and spare parts of electric multiple units

This article firstly discusses the problem about maintenance period of electric multiple units (EMU); Secondly, the types of spare parts and process of calculating the quantity of them during the life cycle period for 30 years are introduced. At last, the determination process of preventive maintenance(PM) and corrective maintenance (CM) spare parts is introduced in detail by taking the secondary suspension of bogie system as example.

DETERMINATION OF THE OPTIMAL PERIOD FOR CARRYING OUT PREVENTIVE MAINTENANCE TO MINIMIZE EXPECTED TOTAL COST

The essential objective of this research is to decide the optimal periods for conducting the preventive maintenance operations (PM) for machines so as to minimize the expected total costs through relying on data concerning the cost of repair or replacement activities (C_s) and the cost of preventive maintenance (C_r). Moreover, the reliability function was calculated for the machines before and after the maintenance operations conducting, considering the data has a Weibull distribution. Also, the application was carried out on real data representing the operating times of the machines between faults for some machines of the National Company for Sponge and Plastic Industry. Thus, the present research concluded that the preventive maintenance works to minimization the total expected costs of maintenance operations, raise the reliability of the machine and its improving, and increase the Mean period of time for machine operation between faults (MTBF) in the case that the shape parameter is increased. However, if the shape parameter is fixed, the preventive maintenance process is useless or with no avail.

Preventive maintenance of mechanical component development guideline on government building based work breakdown structure

Building is a physical form of construction work which is integrated with its domain, partly or fully on the surface and / or underneath the land and / or water, which functions as a place for people to carry out their activities. Buildings must be able to fulfill their functions. However, over the course of time and utilization, they will suffer from damage caused by various aspects, such as the mechanical components of the building. One of the efforts that can be done to reduce the damage is by doing preventive maintenance work. Preventive maintenance work includes tasks or measures taken to prevent the need for repairs. In the buildings preventive maintenance process, the scope of work can be arranged by using Work Breakdown Structure (WBS), hence a structured and activity oriented grouping can be achieved. However, in the application of government buildings there are no guidelines for WBS-based preventive maintenance work yet. Therefore, developing preventive maintenance work guidelines to improve care and maintenance performance is an important task in project management. The research methodology consisted of several stages, namely the literature study, archives analysis with data and information from previous research and related projects, case studies, and Delphi techniques through the validation of experienced experts. The result of this research was that WBS-based preventive maintenance work guidelines for mechanical components of government buildings could improve the quality of buildings and the effectiveness and efficiency of building maintenance.

Linear Sliding Stem Control Valve Hunting Analysis and Extrapolation of Valve Monitoring Features

Control Valve is one of the major final control elements used in industries and plays a vital role in enhancing the productivity of a plant. Optimization of control valve depends on the effective preventive maintenance schedule. Control valves may be overhauled from the pipeline when there is a suspicion of fault. Almost 80% of the control valve maintenance relates to the diagnosis of valve in service to detect any abnormality. When a fault is identified the preventive maintenance process shifts to the breakdown maintenance process. During this process the control valve components are tested to determine the cause of the problem and to establish a corrective course of action. With the developments in microprocessor based control valve instruments along with their diagnostics capabilities has allowed engineers to simplify the maintenance activities. These digital devices can identify problems related with instrument air quality, leakage, supply pressure restriction, excessive friction, dead band, and calibration shift. Troubleshooting control valves after installing in the field is a tedious process as it is difficult to discriminate whether the problem is in the control valve or in the controller tuning. This article presents a novel method using sensors to identify the problems related with the control valve hunting, to pinpoint the source of error and present the performance results to end user. The objective of this research is to reduce manual intervention in troubleshooting of control valves and to enhance the predictive maintenance resulting in cost effective production.

Postupak reparacije guseničnog transportnog mehanizma samohodnog transportera BRs 1200

The paper presents and describes in detail the specific procedures that are carried out during the repair of the crawler unit on the belt wagon BRs 1200.29/32, whose performance is the basis for high quality and efficient maintenance of these machines on site, as well as in repair shops. These procedures are complex interventions performed as part of the preventive maintenance process. The success of the maintenance process is presented as a workflow with as few failures and downtime as possible, also as a process without accidents, and in case of their occurrence, the possibility of the fastest elimination, all of which result in the satisfaction of both users and maintainers.

Improvement of Preventive Maintenance Process Effectiveness in Insourcing and Outsourcing Scheme with House of Risk (HOR) Method Approach (A Case Study)

Outsourcing has become the alternative scheme to gain improvement in several fields within a short time to many enterprises. One power generation in North Java implemented PM as planned maintenance strategy to maintain equipment by conducting insourcing and outsourcing scheme as PM execution. Both conditions must follow the same business process flow in PM execution process and there will occur some obstacles that interrupted PM process. The existing problem will be analyzed with House of Risk (HOR) method approach, supported by Integrated Manufacturing Open Systems Architecture (CIMOSA) process-based function modeling for identification method and Supply Chain Risk Identification System (SCRIS) risk structure identification used for mapping problem, root cause, and its relation. Analysis with HOR results in root causes that occurred within PM implementation process for both of them commonly has the same problem that is process business acknowledgment, but in outsourcing scheme not exist root cause on culture compliance and work task requirement, because they have a descriptive target to obtain service level agreement fulfillment. On both scheme still need an improving method to monitor and evaluate the PM work for better performance.

Reliability Based Analysis of Process Air Compressor in the Petrochemical Industry

The performance and reliability based analysis of process air compressor in the petrochemical industry was carried out. The lognormal model was used for reliability analysis, while the Weibull probability distribution and chi test technique were used to analyzed the sample test questions. The failure based results indicated that for every 1% increase in the lognormal probability, the failure rate increased by 2.4% when compare with that of the Weibull distribution. The Reliability indicates that the reliability of the system for 50days of operation is 36.8%. This increased to 38.8% at the MTBF of 365days. Therefore, there exist a relationship between the system reliability and the failure rate. Base on the chi square test at 0.05 and 0.01 levels of significance it was concluded that “Most Machinery failures are lubrication oriented”. Therefore, careful preventive maintenance process that is condition based should be followed in order to improve the plant energy efficiency.

Interview

Mario A de Oliveira from Mato Grosso Federal Institute of Technology, Brazil, talks to Electronics Letters about his paper ‘Embedded application of convolutional neural networks on Raspberry Pi for SHM’, page 680. Mario A de Oliveira My research involves monitoring structural integrity through the development of new methods to detect and evaluate structural damage, with particular focus on intelligent systems to provide accurate and automatic diagnosis about the overall structural condition. The methods I work on can be applied to several types of structures and across several research fields, such as aerospace, aeronautical, bridges, civil infrastructure, rotating machineries, and wind turbines. I started working in this field during my PhD in 2009. At this time I was very excited to work in this fascinating field and since then I have been focusing on this area. The most interesting issue is developing new methods that can lead to an increase in safety and reduce maintenance costs in structural health monitoring systems. Over the years, structures suffer from degradation and can be damaged without prior warning. A strict preventive maintenance process can prevent major damage and ensure the smooth operation of the infrastructure. However, this process significantly increases operating costs. For this reason, structural health monitoring (SHM) techniques have been extensively studied to increase safety and reduce maintenance costs. For example, owing to the high level of safety required, the aerospace industry has demanded high investments in order to guarantee adequate operating conditions in aircraft. Within this field, surveys have shown that SHM systems could significantly reduce maintenance costs as damage could be detected at an early stage. Although there are several SHM methods in development, methods based on convolutional neural networks (CNNs) are very attractive, especially for those based on images and video processing. This is due to their higher performance in extracting significant features of the damaged area, which can increase the sensitivity of the method making the damage identification. Although many CNN applications that focus on monitoring structural faults have been proposed in the SHM field, the disadvantage of using CNNs is that they rely heavily on the availability of a GPU (Graphics Processing Unit). Furthermore, in several applications such as in aircraft, turbines, and machinery, due to size and weight issues, it becomes costly to install a typical computer within these places. To overcome that, we developed an application embedded in a low cost (about $40) and small hardware (Raspberry Pi). As a result, we demonstrate the power, performance, and feasibility of the application to identify structural failures with good reliability and accuracy. The embedded CNN is promising and may represent a new frontier for the development of low-cost SHM systems. The idea of embedding the CNN algorithm is attractive as the processing occurs locally and the cost of implantation reduces due to a fewer number of components being required. Running the CNN algorithm in a small size, low-cost, low-weight and power hardware can be advantageous from both financial and dimension points of view. Areas that require image processing in real-time could be the most beneficiated to take advantage of the proposed method. In the long term, structural damage detection and classification research is expected to grow rapidly. Methods based on CNNs have exploded in popularity and real world applications using CNNs are one of the most recent major breakthroughs in several areas, including computer vision, speech recognition, biomedical systems and natural language processing. The developing role of image and video processing in SHM systems is obvious in recent years and is expected to grow rapidly in the coming decades. In this context, the embedded CNN algorithm undoubtedly will play an important role. I have been focusing on developing small and compact acquisition hardware to obtain signals from a set of sensors attached to an aeronautical structure. This new hardware will be integrated to the developed CNN application to form a compact and complete SHM system. Of course, new improvements in the CNN-based method will be in course. Since I have been working in the SHM field, the quantity and quality of solutions have been widely exploited. Big companies have proposed embedded SHM systems that could be integrated into their aircrafts; however, this number is still insignificant. Over the next ten years I expect that companies will incorporate more SHM solutions into their aircrafts.

Geometric Process-Based Maintenance and Optimization Strategy for the Energy Storage Batteries

Renewable energy is critical for improving energy structure and reducing environment pollution. But its strong fluctuation and randomness have a serious effect on the stability of the microgrid without the coordination of the energy storage batteries. The main factors that influence the development of the energy storage system are the lack of valid operation and maintenance management as well as the cost control. By analyzing the typical characteristics of the energy storage batteries in their life cycle, the geometric process-based model including the deteriorating system and the improving system is firstly built for describing the operation process, the preventive maintenance process, and the corrective maintenance process. In addition, this paper proposes an optimized management strategy, which aims to minimize the long-run average cost of the energy storage batteries by defining the time interval of the detection and preventive maintenance process as well as the optimal corrective maintenance times, subjected to the state of health and the reliability conditions. The simulation is taken under the built model by applying the proposed energy storage batteries’ optimized management strategy, which verifies the effectiveness and applicability of the management strategy, denoting its obvious practicality on the current application.

Application of physical failure models to enable usage and load based maintenance

The efficiency of a preventive maintenance process largely depends on the ability to predict the replacement intervals of components. Considering the actual usage of the system increases the accuracy of this prediction. The present paper proposes two new maintenance concepts, that combine the benefits of traditional static concepts and condition based maintenance. These new concepts, usage based maintenance and load based maintenance, apply usage or load parameters that are monitored during service to perform a physical model-based assessment of the system condition. The new concepts are positioned within the range of existing maintenance concepts. Also, the role of physical models in maintenance modelling in general is explained and the origin of uncertainty in the predicted service life is discussed. Moreover, it is demonstrated how the monitoring of usage, loads or condition can reduce this uncertainty and increase the service life, by extending existing work in this field. Finally, the different concepts are applied to a gas turbine blade case study to illustrate the benefits of the proposed concepts.

Effects of preventive maintenance on circuit breakers and protection systems upon substation reliability

This paper considers the effects that preventive maintenance on circuits breakers and protection systems inside substations can have on the reliability of electricity supply. By performing preventive maintenance, the probability of a failure to operate of the circuit breaker (unrevealed fault) can be reduced, provided that the preventive maintenance process is carefully carried out. On the other hand, the probability and frequency of an overlapping failure event increases when the frequency of performing preventive maintenance on circuit breakers and protection systems increases. This article shows that an optimal preventive maintenance frequency can be deduced dependent on the substation topology, provided that the maintenance process is carefully carried out. The paper demonstrates also that carelessly performed preventive maintenance can even lead to a decrease in reliability of electricity supply.

Programski paket 'PROFAZ' za upravljanje procesom preventivnog održavanja

Programski paket 'PROFAZ' za upravljanje procesom preventivnog održavanja

Spraywelding—a hard facing preventive maintenance process : J. R. Smith. Iron and Steel Engineer, v. 34, Sept. 1957, p. 90–95

Spraywelding—a hard facing preventive maintenance process : J. R. Smith. Iron and Steel Engineer, v. 34, Sept. 1957, p. 90–95