Home >> Industry Knowledge >> Distributed control system failure resulting in Nitrogen (Nitrogen Equipment) Parking Analysis
After a fault
June 5, 2005 15:36:35, Zhuhai surplus de Gas Co.
Company 16300m3 / h Air Separation Plant in the control room to monitor DCS system operation
Station issued a sudden unusual "toot" sound, followed by addition to circulating water system
Unification large pump outside (because there is no interlocking with the DCS system), all of the
Instantaneous full stop, air separation plant was forced to stop.
DCS system, the historical information recorded as follows:
15:36:35 FCSO101 Too Heavy Load (Controller 0101
Overload, this is the first fault information);
15:36:40 FCSO10l IOM Fail F101 NODE 01 SLOT
04;
15:36:44 FCSO 101 IOM Fail F101 NODE 01 SLOT
01.
All NODE (control of sub-station) and IOM (control processing mode
Blocks) all the failures, all the bits numbers have emerged input circuit breaker
(IOP), the output circuit open (OOP) alarm.
15:37:11 IOM module IOP, OOP police were returning to positive
Chang.
Failure occurred, instrumentation engineer immediately with the DCS system for the
Contact cargo technology, in its guidance, do the following work:
(1) controllers (that is, FCSO101) power, CPU back-up power
Chi also lost power, memory, software program is missing the project.
(2) over 5min, restart the controller, and then instrument
Engineer station to re-project software downloaded to controllers, and re-Kai
Dynamic engineer and operator stations. Occurred after completion of the restart
FCS0101 Too Heavy Load system alarm, but other data significantly
Shown are back to normal.
(3) to resume production as quickly as possible, 19:33:55 start air compressor,
Gradually restore the entire process. However, oxygen compressor starts, some of
Data trends disconnection re-emergence of the phenomenon, and other aspects of
Normal.
2 Failure causes and treatment measures
In April 2005 an air separation plant commissioning process, instrumentation engineering
Process engineers for its software programs to complete the entire project team
State, and passed the test. However, when an air separation plant to open and the entire system
After normal operation, DCS system, trend data record plan appeared off
Line of the phenomenon, and more serious. Did not cause enough
Attention, in fact, DCS system at this time there have been overloaded
Situation, but has not yet reached a critical level.
Failure in this park, DCS system, a "control station system
Unification overload "alarm. The inspection control station FCS0101 of
"CPU IDLE TIME (system idle time)" is 0, indicating the Department of
Commission within the stipulated period of scanning do not have enough time to deal with all .
CPU IDLE TIME longer, the system load smaller.
CENTUM CS3000 R3.03.00 version of the software-related information
Introduced, CPU IDLE TIME is the length of time "with a little
time ", means a little bit of time on it. but in reality should be
Use, the manufacturer recommended CPU IDLE TIME is greater than 9s, that is
System load below 85%; minimum safety value is 5s, the corresponding system
Unification load 91.7%.
Found the problem, the instrumentation engineer project software immediately
Optimize control, will some of which do not need to use "high-speed scan"
The function block to "medium-speed scan" or "basic scan." June 6
Japan 11:57, modify finished, CPU IDLE TIME from 0 to
6s. Continue to observe, DCS trends break the phenomenon did not occur. Also
No other abnormalities. Further optimize the system resources, CPU
IDLE TIME raised to 10s. Failure has been fundamentally resolved.
DCS system supplier sent the software analysis of the project, but also
Confirmed that the substance of the fault because the DCS system load is too large,
Cause the system can not be completed in an instant computing processing and control functions.
In taking measures to address the aforementioned post, in order to further optimize the control
System of the Pc plane itself comes with Windows 2000 operating system
System memory values have also been modified, the minimum increased from 384Mb
To 768Mb, while designated a strict inspection system, by hand for each
Days checking the functioning of the HIS and FCS check including CPU
IDLE TIME and so on.
3 Conclusion
Failure occurs, promptly contact other gas surplus de Gas Corporation
Body of the company's instrumentation engineer to check their own DCS systems (both
For the same type of DCS system) operation, other gases public
Division CPU IDLE TIME, respectively 34s, 5s, 10s, are in an
Within the framework of the whole, but also requires further optimization of system resources, control
System. According to their specific circumstances of the factory in ensuring the safety equipment
Premise, finishing the project software, optimize system resources to ensure the air separation
The normal operation of equipment.