Case studies of application of process immunity time in assessment of Financial Losses due to system faults induced industrial Process Interruptions

In this paper, the assessment of Financial Losses related to Process Trip (FLPT) due to voltage sags and Long Duration Interruptions (LDI) for the whole distribution network is carried out for different operating conditions in order to highlight the importance of probabilistic assessment of FLPT and in particular of inclusion of Process Immunity Time (PIT) in the evaluation. The FLPT due to voltage sags and LDIs are evaluated and compared. A geographic area of the network is clearly identified where high annual FLPT can be expected. It is demonstrated that this area is reduced when PIT is considered. The proposed methodology can be used by utilities to prioritize corrective measures to be taken in different parts of the network to improve quality of electricity supply to affected customers and by end users to assess and reduce their financial losses.