تجزیه و تحلیل کاربردی نقص دستگاه اتصال در برابر فرسودگی
Abstract
1- Introduction
2- System reliability using failures modes
3- New proposal in the failure mode analysis and reliability
4- Case study
5- Discussion
6- Conclusions
References
Abstract
The failure analysis for each component is the biggest problem for maintenance task for switchgears. It should consider the redundant mechanical and electrical systems, in circuit breakers for the analysis. In recently researches, they are often described innumerable system failure modes, according to the methodology applied: RCM plus, RCM 2, among others. Nevertheless, in these methodologies, the specific effects are independently considered (for example the IEEE standard) has proposed 11 failures modes, furthermore CIGRE has proposed 4 evolutionary failures modes however The effects are independent for the failure mode, there is no interaction between them. On the other hand, this research proposes a new perspective with combinations between them and the degradation sequence for ageing process. A proficient method is used to recognize main failure modes, according to IEC 62271–100 (2011) and IEC 62271-1 (2007), later, in the space of arbitrary components, it accomplishes system reliability analysis to calculate the system failure probability, due to reliability analysis, this research proposes a new proposal to complement the IEC standards. To establish the main failure and to propose in decreasing in order their influence. This new proposal to model the searching technique uses the Weibull and gamma distribution. Finally, the authors have done a case study with the new proposal, to prove the reliability goal for contending failure modes under the faster circumstances than traditional methods. In the section 1, the main aspect for the failure analysis in switchgear is described, in the section 2 a system reliability is analyzed with the failure modes criteria: A classical approach and a reliability scope in the analysis. In the section 3 a new proposal is described for a framework, it considers the failure mode analysis and reliability studies, later, in the section 4, the case study is developed with thirty-four hydraulic switchgear and 3201 site acceptance test for preventive maintenance and a section 5, for a discussion about the new proposal in the international standards.
Introduction
In the last years, many papers have studied the failure probabilities, many of them about a single equipment or the behavior in the grid. So far, the reliability study has been done for a particular event, it designated by a particular “limit state function” [1], in the space of arbitrary components. In the literature, the scheme reliability forecast was considered based on dissimilar norms and pertinent, at diverse granularity of data [2]: “One technical solution is of the theory of power system reliability” [3], he has represented quantitatively assessing influences produced by element uncertainties, for example: Unpredicted power plant disconnection. However, this method is appropriate for taking stochastic parameters. Many papers have been developed on its framework, due to evaluate reliability performances for power system analysis, for example: Non-conventional generation and his influence in the smart grids [4]. In the complexity prediction of the failures, the critical arrangement and incorporation of complex engineering procedures [1], with the statistical test have an important value for data integrity. Both the expertise (hardware and software) in addition to in the incorporation of the systems, their data requirement should be verified. About the data, it includes the reliability, availability, maintainability. Besides, the safety process has an important factor in the systems and their associated components [5], the most important concept is the reliability, for the failure analysis [6]. Reliability could be regarded as the probability of effective operation or system performance, associated to their components with the lowest risk, if it has considered the loss or sudden failure. Scheming for reliability needs for a particular assessment of the failure effects, intrinsic systems and components [1]. Reliability forecast in this circumstances can be defined in its simplest form as “estimation of the probability of successful system performance or operation” [10]. Complementary, the reliability evaluation could be conceptualized as “estimation of the probability that an item of equipment will perform its intended function for a specified interval under stated conditions”, as well as, “purpose of the occurrence with which elements failures happen over a specified period of time [7]. Availability considers the equipment maintainability, that is to say: How fast you can change the pieces and turn on the asset for the operation. If an equipment has the availability property, it needs an assessment of the effects of a sudden failure or performance of the integrated systems, and the critical requirements necessary to restore operation or performance to design expectations [26]. Maintainability is a fundamental feature of maintenance task, it considers the downtime for the analysis. If the equipment considered the maintainability design, it needs an assessment of the accessibility, that is to say, if it is easy to replace a component of the inherent systems, besides it considers its associated equipment in the event of a failure, as well as of integrated systems shutdown throughout planned task [7].