PHASE COMPARISON RELAYING SYSTEM WITH SINGLE CHANNEL COMMUNICATIONS LINK

摘要

The square wave phase comparison signals generatedfor each phase of a power distribution system by phasecomparison relays at each end of a protected three phasetransmission line segment are combined to generate a single,multi-level signal with discrete values for eachinstantaneous combination of square wave signals. Thesingle, multi-level signal is used to modulate a carriersignal which is transmitted over a single channel of a two-way communications link to the other terminal where thecarrier signal is demodulated to reproduce the multi-levelsignal. The reproduced multi-level signal is then decodedto generate remote square wave signals which are comparedwith the phase of locally generated square wave signals togenerate trip signals for circuit breakers at the respectiveterminals. Square waves representative of priorityfunctions, such as direct transfer trips, can be integratedinto the single, multi-level signal transmitted to the otherterminal.