Evaluation of reliability of power distribution components: A case study of Sagamu Substation, Ogun State

Power system especially the distribution system which is the closest to the consumer is very fundamental and important to a nation’s economy development and that was the reason this study titled “Evaluation of reliability of power system distribution components, a case study of Sagamu Substation, Ogun State” was carried out in response to the yawning of the consumer for reliable and stable power supply. It is indispensable to find means of shaping which component failure contributes most to the unavailability, outage or interruption of the distribution system, and how this unavailability essentially affects the customers. A year power outages data that caused as a result of failure on each of these components such as Switch gears, Supply lines (11Kv),Busbar, circuit breakers, Fuses, Switches, Outgoings feeders, Over current relays, Earth fault relays, Surge arresters, transformers e.t.c. were collected from Ibadan Electricity Distribution company (IBDEC), Sagamu Substation Zone, Ogun State and were typified in Table 1-11.The failure rate (f/yr) (λ) of transformer, switch gear, supply line (incoming),bus bars, circuit breakers, fuses, switches, outgoing feeder, over current relay, earth fault relay and surge arrester were evaluated as follows 0.0059, 0.0044, 0.0011, 0.6667, 0.0007, 0.0082, 0.0000, 0.0039, 0.0003, 0.0001 and 0.0000 respectively and others such as average outages time (hours) ,outages time hours and other basic reliability indices were calculated and illustrated in Table 12. Some of these failures were also represented in bar chart. This method relates reliability theory with the experience gained from statistics and practical knowledge of components failures and maintenance. The findings from this work revealed that fuses had the highest failure followed by transformers and the least was surge arresters and it was also discovered that the outages time was reduced during the December period. This approach can be applied to rural and urban distribution systems. This submission made reliability theory a powerful tool to assist distribution Engineers in solving difficult and complicated problems.

The Inverse Epsilon Distribution as an Alternative to Inverse Exponential Distribution with a Survival Times Data Example

This paper is devoted to a new flexible two-parameter lower-truncated distribution, which is based on the inversion of the so-called epsilon distribution. It is called the inverse epsilon distribution. In some senses, it can be viewed as an alternative to the inverse exponential distribution, which has many applications in reliability theory and biology. Diverse properties of the new lower-truncated distribution are derived including relations with existing distributions, hazard and reliability functions, survival and reverse hazard rate functions, stochastic ordering, quantile function with related skewness and kurtosis measures, and moments. A demonstrative survival times data example is used to show the applicability of the new model.

A New Variable-Censoring Control Chart Using Lifetime Performance Index under Exponential and Weibull Distributions

In reliability theory or life testing, exponential distribution and Weibull distribution are frequently considered to model the lifetime of the components or systems. In this paper, we design a control chart based on the lifetime performance index using Type II censoring for exponential and Weibull distributions. Average run length helps to measure the performance of the proposed control chart. The optimal values of the number of failure items and decision criteria used to decide whether the process is in-control or out-of-control based on the sample results are determined such that the in-control average run length is as close as to the specified average run length values. We simulate the data to illustrate the performance of the proposed control chart.

The Domain of Residual Lifetime Attraction for the Classical Distributions of the Reliability Theory

The asymptotic behavior of the residual lifetime of the system and its characteristics are studied for the main distributions of reliability theory. Sufficiently precise and simple conditions for the domain of attraction of the exponential distribution are proposed, which are applicable for a wide class of distributions. This approach allows us to take into account important information about modeling the failure-free operation of equipment that has worked reliably for a long time. An analysis of the domain of attraction for popular distributions with “heavy tails” is given.