| Surge
protection at Exxon Aromatics plant, Rotterdam
Over the last couple of years, Esso has experienced the negative effects of lightning induced surges. One such incident occurred at the refinery in Fos Sur Mer in France in 1997 where 3 strikes were detected in the vicinity of the refinery. The consequences were detrimental to the smooth running of the plant with a partial factory shutdown being the ultimate result. The following failures on the DCS system were reported; 150 Digin, 50 Anout, 25 TC and a number of muxes and processor cards in the system. In 1992, Exxon Aromatics factory and Esso Refinery in Rotterdam also suffered system malfunction as a direct result of lightning strikes nearby. Damage caused to the DCS system included a loss of 45 analog output signals, some 15 field transmitters and 6 corrosion probes. Due to these signal losses, some 40 valves took a non-desired position and performance of a number of critical alarms was impaired. Repair time took around 30 hours and the cost in relation to replacing damaged equipment was estimated in the region of NLG 50,000.
The installation of surge protection devices will now be carried out as part of the general maintenance routine and, according to modified directives, all newly installed equipment in sensitive areas will be immediately equipped with protection devices. In the opinion of Mr. Reukers, the costs involved with these programmes are minimal when compared to the consequential disruption caused by system downtime and the cost of equipment repair or replacement. Although lightning storms have frequently
passed the Rotterdam site, no system failures or damage has been
reported since the installation of surge protection devices. |
Mr.
Gerard Reukers, manager of the E&I maintenance department of
Exxon Aromatics, states that nowadays, as a standard routine, surge
protection facilities are installed on all smart transmitters and
valve positioners. Protection devices will be installed on all equipment
not enjoying the protection effect of the metal construction of
the factory (Faraday Cage) and likewise, on all units where zener
barriers are installed, since these cannot withstand high energy
surges. 
