Network protector relay
AssigneeWestinghouse Electric Corp.
InventorDavid R. Smith
Life of this patent
Estimating the term…
Abstract
A network protector relay having trip characteristics which respond not only to the direction of the flow of positive-sequence power through the breaker outwardly of the network but which will respond to unbalanced and simultaneous faults in the feeder network as well. The network protector relay in addition to its tripping characteristics includes closing characteristics which will permit the automatic closing of a breaker only when the phase sequence of the feeder is the same as that of the network, there is a proper phase relationship between the network and feeder and the magnitude of the feeder voltage is such that power flow will be in a direction toward the network.
Claims14
A network protector relay for controlling the connection between a polyphase feeder bus and a polyphase network bus, said protector relay comprising a first circuit means having a polyphase input adapted to be connected to said connection for energization by the current and voltage components of the power flowing in said connection, said means including elements which determine the magnitude of one of said components with respect to the other of said components at first and second time intervals in the wave of said other component, selecting means selecting which one of said time intervals is operative, said first circuit means having an output energized in accordance with the magnitude of said one component, a second circuit means having a polyphase input adapted to be connected to said network bus for energization by at least one of said voltage and current components of said network bus and having an output, said second circuit means including a fault detector energized by said one component of said network bus and effective to provide said output of said second circuit means with an output signal in response to a fault responsive condition of said one component of said network bus of at least a predetermined magnitude, means connecting said output of said second circuit means to said selecting means of said first circuit means, said selecting means being effective in the absence of said output signal to select said first time interval and effective in the presence of said output signal to select said second time interval, and disconnect control means connected to said output of said first circuit means, said disconnect control means being effective to interrupt the connection between said feeder bus and said network bus solely when said magnitude of said one component as established by said elements is greater than a predetermined desired magnitude.
A network protector relay comprising a positive-sequence symmetrical voltage component establishing means and a positive-sequence symmetrical current component establishing means, circuit means energizing said symmetrical voltage component means and said symmetrical current component means with voltage and current quantities from a polyphase network, a negative-sequence symmetrical voltage component establishing means energized from a polyphase network, a disconnect control means having a first input and an output, a gating device having a main path and a control gate controlling the conductivity of said main path, first circuit means connecting said disconnect control means to said positive-sequence current component establishing means including said main path of said gating device, second circuit means connecting said positive-sequence symmetrical voltage component means to said control gate and including selecting means to render said control gate effective to open said main path solely at a first or a second selected time interval in the wave of said positive-sequence voltage component whereby said input of said disconnecting means is energized with a first control quantity having a magnitude proportioned to the magnitude of said positive-sequence current component existing at the selected one of said time intervals, third circuit means connecting said negative-sequence voltage component means to said selecting means, said selecting means being effective to select said first time interval in the absence of a control signal from said negative-sequence voltage component means, said negative-sequence voltage component means being effective to establish its said control signal when the magnitude of said negative-sequence voltage component exceeds a predetermined value, said protector relay further including magnitude sensing means sensing the magnitude of said positive-sequence current component and effective to cause said disconnect control means to provide a tripping signal at its said output solely when the magnitude of said positive-sequence current component passed by said gating device is above a predetermined minimum value.
Dependencies are inferred from the claim text.