【正文】 e 。（8）The average maintenance time of a failure is in 30ms. Available rateThe system design should adopt high reliability ponents, the realtime operating system should has practical running experience, the software should be practical, then the system can obtain high availability. The total failure time of the system should not exceed 1% of the running time during the oneyear guarantee time of after one year trial operation and equipment acceptance check. CPU loading rateThe processing ability of the monitoring puter has sufficient adequacy and ability storage over 50%, the CPU ability storage of PLC over 20%. System safetyThe specific measures for the system safety on operation, munication, hardware, software and fixed ware are as follows. Guarantee measures for operation safety（1）Every function and operation of the system has check and verification, warning and cancel would be took place when error is founded 。（2）When the high level of water allocation center and the field monitoring system has control message, it should has clear and confirm mand。（3）Any hardware and software failure doesn’t affect the safety on people and system。（4）The passage using rate has over 50% adequacy.（5）Adequate space is prepared in equipment cabinet. The Performance of SoftwareThe remote monitoring system includes the software in operating systems, support program and practical program, databases, humanputer interfaces, munications, applications, video systems and so on. The performances of that software are as follows: The Operating System Software（1）It can manage the system resources.（2）It has the ability to control the import and export equipment directly.（3）It can implement the highlevel language program effectively.（4）It has interactive language mand which can support the system activities of the startup, termination, monitoring, configuration, and other online activities.（5）It can realize the connection of those software though the task name, the data name and operate symbols.（6）It can provide services for system generation. Support Program and Practical Program（1）It has effective programming software which can be used to develop application software. Those programming software include the standard assembly language, highlevel language piler, interactive graphics piler, interactive report piler, and ladder using for the PLC programming, and so on.（2）It has connect and assembly process which used code pilation and can be easily used.（3）It has practical process which can test and revise the application software with the terminal equipment.（4）It has the practical program for the memory redeposit. Database Software（1）The structure and organization of the database can support the application to have a direct access to data and realize the inquiry, revision and expansion of data.（2）It can maintain the high independence between applications and data.（3）It can maintain the reliability of the data in the database and provide data protection to prevent improper modification whether is caused by manmade or procedure.（4）The database software can dispose the measurements while excess the limits, and it is timing and regular to archive and retrieve data.（5）The emendation of database is separately used two forms of static data and dynamic which is achieved by relevant editing process and other procedures.