Time delay signal device especially for phase comparison protective relaying system

Claim 1

A relaying system for comparing the phase of an alternating electrical quantity at first and second spaced locations, first and second sensing networks, first means connecting said first network to respond to said quantity at said first location, second means connecting said second network to respond to said quantity at said second location, a plurality of timing devices, the timing interval of each of said timing devices being less than the interval of a half cycle of said electrical quantity, a bistable means having first and second stable conditions, third means connecting said first network to said bistable means and including first of said timing devices, said third means being effective to initiate a said timing interval of said first timing device and to place said bistable means in its said first condition at fixed intervals relative to the alternation of said quantity, said first timing device being effective at the end of its timing interval to place said bistable means in its said second condition, a first comparing network for comparing the relative phase of two input signals, fourth means connecting said bistable means to said comparing network and including a second of said timing devices, said bistable means being effective upon being placed in its said second condition to initiate a timing interval in said second timing device, said second timing device being effective as a consequence of its completion of its said timing interval to provide a first of said two input signals to said comparing network, a transmitting device at said second location, fifth means connecting said transmitting device to said second network, said transmitting device being effective to transmit a signal indicative of the phase of said electrical quantity as detected by said second network, a receiving means at said first location having an output circuit, said receiving means being effective to receive said signal transmitted by said transmitting device and to energize its said output circuit with a second quantity of constant phase with respect to said transmitted signal, sixth means connecting said output circuit to said comparing network and effective to supply the second of said two input signals thereto, and an output device connected to said comparing network and energized thereby at predetermined relationships of said two input signals, the total time of said timing intervals of said first and second timing devices being a fixed proportion of the total time for the transmission of the phase signal of said electrical quantity from said second location to said comparing network whereby said comparing network is effective to provide said predetermined relationships of the phase of said quantity at said first and second locations.