【正文】 s to a remote location (known as important to ensure that these additional functions do not jeopardise the inherent integrity In recent years, technological progress has led to the use of microprocessors in protective relay manufacture. This has led to: ? A significant increase in the amount of information that is processed by the relays. ? Easy calculation of electrical quantities such as harmonics. ? Secure and reliable exchange of digital information with remote locations. ? Continuous monitoring of protection relay integrity by selfsupervision and autodiagnostics. CEE have developed the PROCOM range of digital protection relays, which benefits from the above advantages without sacrificing the standalone capability of the classical solid state relays such as the ITG and TTG series. In addition to the PROCOM protection relays such as the RMS, RMSD, RMSR, IMM, GMS and DMS relays, the PROCOM range also includes the CMS digital instrumentation units, AMS local PLCs and PMG. It is therefore possible, by selecting the appropriate bination of units, to define a plete circuit breaker local management system including Protection, Automation and Instrumentation. Nowadays, the difficult economic environment within the industry is imposing increasing demands on efficiency by reducing operating and maintenance costs. At the same time, improvements are required in the continuity and quality of supply, together with personnel and equipment safety. With these trends in mind, CEE has recently developed the PROSATIN range of equipment, which bines the capabilities of the PROCOM range with that of the MicroSATIN range to provide the plete Integrated Protection, Supervision and Remote Control of Electrical Power Networks. The PROSATIN systems therefore provide full SCADA function for Electrical Power Networks, bining the following functions: ? Protection ? Supervision (Measurements, Alarms, Data Logging and Mimic Diagrams) ? Control (Local or remote by VDU) PROSATIN reduces costs and improves continuity of supply by: ? Reducing the time to check and analyse the power system operational status of parameters, ? Increasing preventative maintenance by automatic and continuous supervision including autodiagnosis, ? Optimisation of energy costs, and ? Improvements in operational procedures and maintenance leading to reduced downtimes. In order to be adaptable to varying degrees of user needs, PROSATIN is available in the following subsystems: ? PS1000: Simple supervisory systems based on desktop PCs intended for use in relatively small electrical works. ? PS2021: SCADA system with time logging for industrial plants and distribution works. ? PS4000: Complete highspeed SCADA system for industrial plants. The selection of protection relays therefore depends upon the answer to two basic questions: a) What are the local protective functions necessary to give the best conditions for the Power System Safety and fault discrimination? b) Will the power system be supervised or controlled in the future? The answer to the second question determines the type choose the classical solid state protection, or the more modern microprocessor controlled digital relays. The answer to the first question determines the selection of protective relay types and their setting ranges. This, together with the power system behaviour (under both steady state and transient conditions) is the subject of this guide. Note that the PROSATIN modular architecture enables a gradual stepbystep implementation of a full