Ferroresonance Study Using False Trip Root Cause Analysis

It is vital in the prevention of the ferroresonance to consider this phenomenon from new side. The design of the equipment needs deep studies to avoid such disturbance. This paper presents a new way in ferroresonance studies, by the use of the Root Cause Analysis (RCA) in a systematic step by step process to discover the true cause of this problem. A fault tree is built to identify all possible causes leading to the unwanted top event, that is the False Trip Analysis (FTA). Among large statistics of disturbances, the probability of occurrence of ferroresonance is stated, and using the most studied causes of this event, the tree of analysis is built till reaching the main disturbance. In each step, well-known possible causes are shown. Then, a barrier or possible solution corresponding to the cause is presented. The new probability of occurrence is then calculated. The obtained result is compared to the initial probability and a set of protection system is proposed. The advantage of this study is the possibility to reduce the occurrence of the ferroresonance by gathering the maximum detailed amount of possible causes and by choosing the best barrier corresponding to the cause. (C) 2019 The Authors. Published by Elsevier Ltd