Practical risk assessment of the relaxation of LOM protection settings in NIE Networks' distribution system

This study presents the methodology, experience and practical outcomes of the risk assessment-based revision of loss-of-mains (LOM) protection settings in the NIE Networks' distribution system. An investigative project has been undertaken by the authors to revise the current LOM practice as recommended by the G59/1/NI regulation and to propose the settings which would meet the all-Ireland transmission system stability criteria. It is also important to ensure that any increased personal risk is realistically quantified and satisfies the health and safety requirements. Both aspects (i.e. LOM protection stability and sensitivity) are covered in the study. The results and observations included in the study aim to provide the means and supporting evidence for achieving the best compromise in the revision of LOM protection settings.