Abstract
Based on NFPA-780, offshore platforms, which made from metal framework of a structure are thought of as "grounded" to the ocean and therefore are not needed to be installed external Lightning Protection System (LPS). PHE ONWJ which located at offshore tropic area has implemented NFPA 80 but still experience lightning hit. It generated fire at vent stack andcause operations interference. So that, the objective of this study is to redesign LPS for tropic area. Firstly, the methodology for this study was conducting literature review from previous researches for lightning protection system at tropic area and researches which underlyingNFPA-780. The literature reviews were focusing on lightning characteristic for tropic area andthe lightning density data from local lighting strike monitors surrounding PHE ONWJ. The result of literature reviews would be the basis of lightning strike event reviews in PHE ONWJ facilities. Subsequently, the authors conducted the equipment layout review using rolling sphere method based on previous lightning strike location. Lastly, Authors proposed the recommendationsfor typical LPS for oil and gas at tropic area. Based on literature reviews,lightning characteristic at tropic area has peak strike current twice the sub-tropic and longer "tail" so that the charge current is larger. Larger the charge current of lightning cause greaterimpact into metal structure that is metal melting. Based on NFPA 780/2011, the offshore platform, which is made by metal, and vessel with minimum thickness 4.8 mm are self-protected. However, based on calculation, with the characteristic of lightning at tropic area, the recommendedminimum vessel thickness is 10 mm. This calculation reinforces the fact that standard of Lightning Protection System in NFPA 780/2011 is not sufficient to be applied in tropic area like Indonesia. After calculating the tropic lightning strike range using rolling sphere method, it isrecommended to redesign lightning protection system for some locations at offshore platform and near shore facilities of PHE ONWJ.The lightning protections system locations and quantities are depending on the area and the needed protected equipment in it.The installation isincluding extended mast terminal, free standing mast, low inductive Double Shielded Down Conductor(DSDC), Lightning Event Counter (LEC), and good grounding system at the platform.
Study on lightning protection scheme of multi-terminal MMC-MVDC distribution system
