Whether it is a new unit or an upgraded DCS, the equipment of the system and controller should focus on the reliability and load factor (including redundancy) objectives. The communication bus load rate planning must be controlled within a reasonable range, and the load rate of the controller should be balanced as much as possible, so as to prevent the occurrence of "high load" problems that affect the safe operation of the system due to the lack of funds involved in large scale.
The distribution of system control logic should not be excessively concentrated on a certain controller, and the main controller should be redundant equipment.
Power planning must be reasonable and reliable. First, it is necessary to focus on the load rate of power supply planning; Second, it is necessary to pay attention to the redundant equipment method of the power supply, and at the same time it is necessary to ensure the independence of the two power supplies.
It is necessary to pay attention to the reliability of the DCS system interface. Focus on the redundancy of important interfaces and the selection of interface methods, mainly paying attention to reliability and real-time.
The grounding of the DCS system must be implemented according to the requirements of the manufacturer to prevent the grounding problem from forming a large-scale problem in the system. Attention should be paid to the anti-interference method, self-diagnosis and self-recovery ability of the system, and the I/O channel should focus on the isolation method. The quality and shielding of the cable must also be paid great attention to, and the special shielded cable for the computer should be used for important signals and control.
It is necessary to fully consider the controllability of the main and auxiliary equipment, and equip the operator station and backup manual operation equipment according to the operation characteristics of the equipment and the requirements of the unit to deal with urgent problems under various working conditions. The emergency shutdown button equipment should be equipped with a separate operation circuit separate from the DCS. At the same time, we should not blindly pursue the "simplification" of the human-machine interface, and the system equipment should also be satisfied with the safety of production as the first place. Urgent interventionist operations, especially with regard to safety, cannot be built on a thoroughly sound foundation of the DCS.
For the actuators, valves and other peripheral equipment involved in the safety of the unit, when planning and equipping, it is necessary to ensure that these key equipment can act in the safe direction or remain in place in the event of power loss, gas loss, signal loss or DCS system failure.
Regarding the protection system, the multiplexing signal acquisition method should be selected, and the blocking condition should be used reasonably, so that the signal loop has the ability to make logical judgment.
During the commissioning period, all logic, loops and working conditions are tested according to the debugging outline and specific methods.
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