IEC 60870-4-1990 pdf free download – Telecontrol equipment and systems Part 4: Performance requirements.
This series of standards applies to telecontrol equipment and systems with coded bit serial data transmission for monitoring and control of geographically widespread processes. The scope of this standard embraces telecontrol systems in the restricted sense, as shown in IEC Publication 870-1 -1 , figure 2.
2. Object
This part deals with those characteristics which affect the perform- ance of telecontrol systems and relates the characteristics to the application and processing functions.
The object of this part is to establish a set of rules which can be used to assess and specify the performance requirements of telecontrol systems.
It is intended that this part serves as a common platform for the system planner and the supplier or manufacturer of telecontrol systems. The system planner will find the contents helpful in determining the requirements for a particular telecontrol system. In addition, these rules provide a means of comparing the products of different suppliers. The supplier or manufacturer will find guidelines for the system design and a base for classification of system performance.
This part comprises a main body, which contains the actual standard, together with two appendices, which contain further information and recommendations.
The main body is devoted chiefly to a treatment of the various characteristics as operational parameters. A short description of each operational parameter is followed by a list of the necessary performance requirements and, where feasible, a classification of the operational parameters in performance classes.
The performance classes serve to specify the system requirements for a particular application and to evaluate the system performance of different telecontrol systems.
The performance classes used are to be optimized for each application and agreed upon between the user and the supplier.
3. Classification of operational parameters
This clause covers those properties which influence the performance of telecontrol systems. Appropriate requirements and, where feasible, performance classes have been specified for each of the properties covered.
The classification ratings given apply in general to the performance of the units of the overall system. The performance of the overall system shall be derived from the performance of all components of a telecontrol system (in the restricted sense), excluding the process and the operator’s equipment. Certain properties, however, such as reliability and availability, can be applied as performance criteria to individual items of equipment. The components of an overall system are, for instance:
– substations;
– nodes;
– transmission lines,
– central processor;
– man/machine interface.
The requirements for a particular telecontrol system are dependent on the specific application and are invariably subject to agreement between supplier and user.
3.1 Reliability
Reliability is defined as a measure of an equipment or system to perform its intended function under specified conditions for a specified period of time (see IEC Publications 271, 271A and 300). It is a probability figure, based on failure data and length of operating time.
The reliability of a telecontrol system is expressed by the “mean time between failures” in hours (MTBF), and can be calculated from the reliability figures of the individual system components (see the standards of Technical Committee No. 56) .IEC 60870-4 pdf download.