BS 7404-4:1991

Committees responsible
Foreword
Specification
Introduction
1. Scope
2. Object
3. Classification of operational parameters
3.1 Reliability
3.2 Availability
3.3 Maintainability
3.4 Security
3.5 Data integrity
3.6 Time parameters
3.7 Overall accuracy
4. Expandability
5. Influence of telecontrol equipment on the
     environment
5.1 Electrical influence
5.2 Acoustic noise
5.3 Thermal influence
Appendices
A. Measures to enhance system performance
B. Evaluation of expandability
Tables
1. Reliability classes
2. Availability classes
3. Maintainability classes
4. Repair time classes
5. Data integrity classes
6. Separating capability classes
7. Time resolution classes
8. Overall accuracy classes
9. Starting current classes
B.1 Extensions to process data
B.2 Extensions to application functions
B.3 Extensions to additional processing functions
B.4 Extensions to data transmission
Figures
1. Processing of analog information
2. Noise criters (NC) curves for speech communication

Applies to systems with coded bit serial data transmission for monitoring and control of geographically widespread processes.

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.