Reverse power flow relay

Claim 2

A power flow direction relay for a power transmitting circuit, said relay comprising: first and second input circuits and an output circuit, said input circuits being energized with first and second alternating quantities representative of the current and voltage in said power circuit, a first switching device having a main circuit and a control circuit for initiating a change in the conductive condition of said main circuit, a pulse generator, first circuit means connecting one of said input circuits to said control circuit of said switching device and including said pulse generator, second circuit means connecting the other of said input circuits to said output circuit and including said main circuit of said switching device, said pulse generator being effective to actuate said control circuit to initiate a change in the conductive condition of said main circuit solely during a predetermined time interval in degrees of the one alternating quantity which energizes said one input circuit, said output circuit including a high gain amplifieR and a feedback circuit, said feedback circuit including a timing network, said timing network comprising a primarily reactive device and a primarily resistive device, said timing network having a time constant substantially greater than said predetermined time interval, said second circuit means connecting said other input circuit through said main circuit of said switching device to the input of said amplifier.

Claim 3

The relay of claim 1 in which said pulse generator renders said control circuit effective to render said main circuit conductive during said predetermined interval.

Claim 4

The relay of claim 2 in which said main circuit of said switching device conducts bi-directionally, said output circuit including a polarity sensitive device which is actuated to transmit an output signal solely when the conduction through said switching device is in a first direction.

Claim 5

The relay of claim 3 in which said amplifier comprises a operational amplifier having a negative input terminal and a positive input terminal and an output terminal and first and second energy supplying terminals, a unidirectional power supply having a positive terminal and a negative terminal and a third terminal, said power supply being effective to maintain the potential of said third terminal intermediate that of said positive and negative terminals, said primarily reactive device being connected between one of said input terminals of said operational amplifier and said third terminal, said primarily resistive device being connected between said output terminal of said amplifier and a desired terminal of said input terminals of said operational amplifier, said second circuit means connecting said other input circuit through said main circuit of said switching device between a selected terminal of said input terminals and said third terminal of said power supply, and means connecting said positive and negative terminals of said power supply to said energy supplying terminals of said operational amplifier.

Claim 6

The relay of claim 4 in which said desired terminal and said one input terminal are said negative input terminal of said operational amplifier and said selected terminal is said positive input terminal of said operational amplifier.

Claim 7

In combination, a power transmitting circuit having an input for energization from a source of alternating potential energy and an output for energizing an energy consuming load, a pulse generator having an input connected to said power circuit and energized with a first alternating quantity having a predetermined phase relation with respect to the phase of one of the alternating potential and current of said power, a solid state switching device having a main circuit and a control circuit which controls the conductive condition of said main circuit, said generator having an output connected to said control circuit and effective to place said control circuit in condition to render said main circuit conducting solely at a predetermined degree time in the wave of said first alternating quantity and solely for a predetermined number of degrees of said first alternating quantity, a polarity sensitive network having an input connected to said power circuit through said main circuit of said solid state device and energized with a second alternating quantity having a predetermined phase relation with respect to the phase of the other one of the alternating potential and current of said power, said polarity sensitive network having an output energized solely when said second alternating quantity which is supplied to said input of said polarity sensitive network is at a first polarity, said first polarity of said second quantity being indicative of a flow of power in said power circuit from its said output to its said input, said power transmitting circuit including a circuit interrupting device controlling the connection thereof to said load, said output of said polarity sensitive network being operatively connected to said disconnecting device, said polarity seNsitive network being effective when its said output is energized to cause said circuit device to disconnect said power transmitting device from said load, said polarity sensitive network including an operational amplifier having a pair of input terminals and an output terminal which changes in potential with respect to ground as a function of the polarity of the potential which is applied between a first of said pair of input terminals and ground, a capacitor connected between ground and a second of said pair of input terminals, a resistor connected between said second input terminal and said output terminal of said amplifier, said input of said polarity sensitive network being operatively connected between said first input terminal of said amplifier and ground, said output of said polarity sensitive network being operatively connected between said output terminal of said amplifier.

Claim 8

In combination, a power transmitting circuit having an input for energization from a source of alternating potential energy and an output for energizing an energy consuming load, a pulse generator having an input connected to said power circuit and energized with a first alternating quantity having a predetermined phase relation with respect to the phase of one of the alternating potential and current of said power, a solid state switching device having a main circuit and a control circuit which controls the conductive condition of said main circuit, said generator having an output connected to said control circuit and effective to place said control circuit in condition to render said main circuit conducting solely at a predetermined degree time in the wave of said first alternating quantity and solely for a predetermined number of degrees of said first alternating quantity, a polarity sensitive network having an input connected to said power circuit through said main circuit of said solid state device and energized with a second alternating quantity having a predetermined phase relation with respect to the phase of the other one of the alternating potential and current of said power, said polarity sensitive network having an output energized solely when said second alternating quantity which is supplied to said input of said polarity sensitive network is at a first polarity, said first polarity of said second quantity being indicative of a flow of power in said power circuit from its said output to its said input, said power transmitting circuit including a circuit interrupting device controlling the connection thereof to said load, said output of said polarity sensitive network being operatively connected to said disconnecting device, said polarity seNsitive network being effective when its said output is energized to cause said circuit device to disconnect said power transmitting device from said load, said polarity sensitive network including an operational amplifier having a pair of input terminals and an output terminal which changes in potential with respect to ground as a function of the polarity of the potential which is applied between a first of said pair of input terminals and ground, a capacitor connected between ground and a second of said pair of input terminals, a resistor connected between said second input terminal and said output terminal of said amplifier, said input of said polarity sensitive network being operatively connected between said first input terminal of said amplifier and ground, said output of said polarity sensitive network being operatively connected between said output terminal of said amplifier.

Claim 9

The combination of claim 6 in which means is provided to limit the magnitude of said second quantity.

Claim 10

The combination of claim 6 in which means is provided to limit the magnitude of said second quantity which is supplied to said switching device.

Claim 11

The combination of claim 6 in which means is provided intermediate said input of said polarity sensitive network and said switching device to limit the magnitude of said second quantity which is supplied to said input of said polarity sensitive network.

Claim 12

The combination of claim 8 in which means is provided intermediate said input of said polarity sensitive network and said switching device to limit the magnitude of said second quantity which is supplied to said input of said polarity sensitive network.