Case analysis and treatment of lightning strike on

Case analysis and treatment of lightning strike on DCS of oxygen plant

the 2 # oxygen generator in the old area of our plant was completed and put into operation in September 2003. The DCS control system adopts the JX-300X control system of central control technology company. The system has been running well since it was put into operation, but since 2006, the system has suffered two lightning accidents, which seriously threatened the safe and stable operation of the oxygen generator. This paper introduces that after the JX-300X control system of our factory was struck by lightning, we can make full use of the existing equipment conditions, flexibly use the hardware fault judgment technology of the system, and combine the skills explored in the actual work to better judge the location of the fault card, and successfully deal with the DCS lightning fault without stopping the machine

2 lightning accident phenomenon and treatment

on June 28 and July 7, 2006, the DCS control system of our 2# oxygen generator was struck by lightning twice. The process personnel checked that the on-site equipment was not shut down, and the on-site process parameters were normal, but most of the parameters could not be adjusted normally

2.1 instrument and control inspection

dc comprehensively integrates producers and consumers. After measuring the s control system 1 # cabinet hardware fault diagnosis screen for 3 (5) times, the instrument should be cooled in a natural state. The instrument displays 2 # address master card (sp243x) i/o controller fault, all cage communications are interrupted, all data transfer cards (sp233) flash red, all control system detection point data are maintained, and a total of 12 cards are damaged, including 8 data transfer cards (sp233) There is a master control card and an analog input card (sp313), which are distributed in the first cage of 1# cabinet. At the same time, two transmitters were damaged on site: one was high-pressure nitrogen pressure, one was medium pressure nitrogen pressure, one measuring point was located in the gas supply distribution room 150m away from the central control room, and the other measuring point was located near the medium pressure nitrogen main pipe 100m away from the central control room

2.2 fault diagnosis

2.2.1 1 the communication of the cabinet control system has been completely interrupted and the data has been maintained. It is mainly caused by the communication interruption between cages and between cages and between cages and master card (sp243x) due to the failure of data transfer card (sp233) (the possibility of bus failure is small)

2.2.2 the i/o controller fault alarm of the address master card (sp243x) may be caused by the master card (sp243x) fault

2.2.3 because JX-300X control system has the characteristics of redundant work of master control card (sp243x application copolymerization modification makes EPS monomer particles have the same characteristics as fire-proof materials), redundant work of data transfer card (sp233), and maintenance of analog input card (sp313), DCS control system did not cause partial action of on-site instrument and control when it was struck by lightning, so it did not cause on-site shutdown

2.3 emergency treatment measures

2.3.1 according to the situation that the on-site equipment has not been shut down and the on-site process parameters are still normal, the I & C DCS should be quickly restored to use to avoid forced manual shutdown due to process reasons. We took the measure of transferring the data transfer card (sp233) (one piece for each cage) from the 2 # cabinet to the standby data transfer card (sp233) position of the same cage in the 1 # cabinet (the first cage is transferred), We found that the communication of the first cage had been established, and by analogy, we replaced other cage cards. We found that some data transfer cards (sp233) still flashed red in the hardware fault diagnosis screen. We observed that the data transfer cards replaced later were in working state (1# the data transfer cards not replaced in the cabinet were in standby state). We tried to pull out all the data transfer cards not replaced, and finally found that the basic communication had been established

2.3.2 according to the fault analog input card (sp313), it is found that the damaged are the 13 # and 14 # cards of the first cage of the control system 1 # cabinet, and the 7-point signals of the 2 cards (a total of 8-point signals) are in the same signal cable, and the other point is separately in a shielded cable (near the medium pressure nitrogen main pipe 100m away from the central control room). Lightning strike may be from this signal cable

3 lightning accident analysis and preventive measures

3.1 failure card maintenance report analysis

master control card (sp243x):

replace the DS75176BN (u13) dip module in the card. Card failure analysis: the card communication interface circuit has strong signal access, causing card failure and unable to work normally

data re issuance (SP2 seizes the opportunity of "8 vertical and 8 horizontal" high-speed rail and national "1 belt and 1 road" at the same time):

replace the DS75176BN (u9) dip module in the card. Card failure analysis: the card communication interface circuit has strong signal access, causing card failure and unable to work normally