Re-design AC Power Failure Signal to Minimize False Signal of Emergency Shutdown System for Ethylene Plant

Chandra Asri, the largest integrated petrochemical company in Indonesia, requires a reliable electrical system to ensure production. Electrical power was supplied by the grid from PT. PLN through a 150 kV system in parallel with captive generation. The electrical system uses the Emergency Shutdown System (ESD) to protect against various disturbances that can cause equipment damage and work accidents. ESD will only work if things happen according to a logic diagram that has been designed according to the needs. One time, there was a power outage due to the active ESD. This causes huge losses for the company. The results of the investigation showed that there were no disturbances to either the grid or the captive generator. It is suspected that there is a false signal that causes the ESD to activate from the DC charger signal. For this reason, efforts are needed to eliminate the possibility of this nuisance signal occurring in the future by redesigning the logic and signal source of AC power failure by considering the existing secondary selective electrical system. Modification of the ESD system is carried out in 5 stages, namely 1) fault analysis, 2) modification of logic diagram design, 3) system development, 4) testing, and 5) evaluation. The results of the redesign decided that modifications should be made to the ESD system and carried out on the next Turn Around Maintenance schedule because this modification requires an offline electrical system. The analysis and simulation results show that the ESD system is safe against similar disturbances. It is hoped that the redesign and modification of the ESD system can prevent signal interference in the AC Power Failure Signal.