IEC 60870-4:1990 pdf free download

IEC 60870-4:1990 pdf free download
IEC 60870-4:1990 pdf free download.Telecontrol equipment and systems
3.4 Security
The security of a telecontrol system can be defined as its ability to avoid placing the controlled system in a potentially dangerous or unstabie situation. it deais with the consequences of faiures. arising out of maifunctions of the telecontrol equipment, undetected information errors as well as information los ses .
The consequence of a failure may depend on the state of the power system at the instant of failure. A dangerous situation can arise out of a combination of a failure of the telecontrol system with a particular situation of the power system. In such cases, the p robability of occur- rence of a dangerous situation is the product of the probability of occurrence of the failure and the probability of occurrence of the particular situation in. the power system，provided that the two occu rrences are independont of each other.
Measures to enhance,the security are given in appendix A, clause A.4.
3.6 Time parameters
The time parameters referred to are. those concerned with the performance of telecontrol systems， together with the transfer and processing of information.
In the field of telecontrol, the most crucial time parameter involves the time taken to transfer information f rom the source to the . destination. Designated as the overall transfer time, it is defined in . IEV 371-08-15 as:
“The time duration by which information is delayed after the actual event in the sending station . and until presentation at the receiving station
The overal! transfer time is used as a performance rating factor for teiecontroi systems， as weii as to specify the major time requiremenis for a particular applica tion.
The essential difference between these two categories concerns the overal! transfer time. The high priority information has to be transferred as fast as possible and thus should have the shortest overall transfer time.