Patent EP-0222682-B1 (EP)
IPC: H02H1/00
Filed: 1986-10-03
Granted: 1990-07-18
Abstract: 1. Signal transmission arrangement for a comparison protection device, in which measured variables are detected at two ends of a protection section (5) of an energy transmission system, which section is to be monitored, in respectively one monitoring station (1, 2) and in each monitoring station, in each case as a function of the measured variables detected in both monitoring stations, a switch-off signal (10, 11) is generated for a switch (12, 13) at the respective end of the protection section, having a signal line (14), connecting the two monitoring stations, for transmitting the measured variables or a comparison variable which is established from them and having two transmitting/receiving devices (15, 16), each of which has a frequency signal generator (30) and a frequency signal receiver (32) with an error signalling output (25, 26) and also a transmitter (34), the frequency signal generator of one of the two transmitting/receiving devices communicating on the output side, by way of the pertinent transmitter, with one end of the signal line and the frequency signal receiver of the other transmitting/receiving device being connected on the input side, by way of the corresponding transmitter, with the other end of the signal line, characterised in that in both transmitting/receiving devices (15, 16) in each case the output (31) of the frequency signal generator (30) is connected with the input (33) of the frequency signal receiver (32), in that each frequency signal generator (30) has a control input (17) which can be activated by means of a lock-in signal, in that the frequency signal generator (30) of the one transmitting/receiving device (15) is formed for the emission of a first frequency signal, which is clocked with a given keying and keying pause time, in the case of deactivated control input (17), in that the output (31) of the frequency signal generator (30) in the other transmitting/receiving device (16) is switched off in the case of deactivated control input (17), in that both frequency signal generators (30) can be activated by action of the lock-in signal on the control input side in each case for the emission of a second clocked frequency signal on the output side with a further given keying and keying pause time, in that each frequency signal receiver (32) contains, in each case, a signal evaluation device (57) which is connected to its input (33) and which on the output side emits a switch-off signal for the switch (12, 13), associated with the relevant monitoring station (1, 2), as a function of the fact that there occurs at least once at the input (33) of the frequency signal receiver (32) a frequency signal with a signal duration, which corresponds at least approximately to the further keying time, and subsequently a signal pause which corresponds at least approximately to the further keying pause time and in that each frequency signal receiver (32) contains a time lapse stage which has a reset input arranged after the input (33) of the frequency signal receiver (32) and forms on the output side the error signalling output (25) of the relevant frequency signal receiver (32).