US 4,538,196 A · Protective relay apparatus and method for providing single-pole tripping

Abstract

A new protective relay for determining the occurrence of a single-phase-to-ground fault and tripping the appropriate circuit breaker. At local and remote terminals of a protected line segment, three signals representative of an electrical parameter on each phase conductor are input to a local and remote protective relay. In both the local and remote protective relays, the three electrical parameter signals are manipulated to produce two evaluation signals. The two local evaluation signals produced in the local protective relay are transmitted to the remote protective relay, and the two remote evaluation signals produced in the remote protective relay are transmitted to the local protective relay. In the local protective relay the two local evaluation signals are manipulated to produce a third local evaluation signal, and the two remote evaluation signals are manipulated to produce a third remote evaluation signal. The six evaluation signals are vectorially-compared to determine on which phase the fault has occurred. Only the circuit interrupter associated with the faulted phase conductor is tripped. If a fault involves two or more phase conductors, all three circuit interrupters are tripped. Similar signal processing occurs in the remote protective relay.

Claims38

Dependent claims

A phasor-comparison protective-relay system detecting the faulted phase conductor of a three-phase ac transmission line section having a circuit interrupter on each of the first, second, and third phase conductors at each of the local and remote terminals thereof, said phasor-comparison protective-relay system comprising:

means at each of the local and remote terminals responsive to first, second, and third electrical parameters thereat for providing first and second local derived signals at the local terminal, and first and second remote derived signals at the remote terminal;
means at each of the local and remote terminals for transmitting said first and second local derived signals to the remote terminal and for transmitting said first and second remote derived signals to the local terminal;
means at each of the local and remote terminals for expanding said first and second derived signals received from the other into first, second, and third local comparison signals at the local terminal and first, second, and third remote comparison signals at the remote terminal;
and comparator means at each of the local and remote terminals for logically relating said first, second, and third local comparison signals at the local terminal and said first, second, and third remote comparison signals at the remote terminal to detect the faulted phase conductor and for tripping the circuit interrupter on the faulted phase conductor at each of the local and remote terminals.

1 more element

A phasor-comparison protective relay tripping a faulted conductor of a three-phase ac transmission line section having a circuit interrupter on each of a first, second, and third phase conductors at local and remote terminals thereof, wherein local circuit interrupters are controlled by said phasor-comparison protective relay at the local terminal and remote circuit interrupters are controlled by a remote protective relay located at the remote terminal, and wherein said phasor-comparison protective relay and the remote protective relay are in communication via a communications channel, and wherein the remote protective relay includes a remote receiver and a remote transmitter, and wherein the remote transmitter transmits a plurality of remote status signals to said phasor-comparison protective relay representative of the electrical status of the first, second, and third phase conductors at the remote terminal, said phasor-comparison protective relay comprising:

means at the local terminal responsive to first, second, and third electrical parameters thereat for providing first and second local derived signals;
local transmitter means for transmitting said first and second local derived signals to the remote receiver via the communications channel, wherein the remote protective relay is responsive to said first and second local derived signals for controlling the circuit interrupters at the remote end;
local receiver means responsive to the plurality of remote status signals transmitted by the remote transmitter via the communications channel, for producing a plurality of received signals in response thereto;
means reponsive to the plurality of received signals for producing first and second remote derived signals;
means for expanding said first and second local derived signals and said first and second remote derived signals into first, second, and third comparison signals;
comparator means for logically relating said first, second, and third comparison signals to detect the faulted phase conductor and for tripping the local circuit interrupter on the faulted phase conductor.

3 more elements

A method for detecting the faulted phase conductor of a three-phase ac transmission line section having a circuit interrupter on each of the first, second, and third phase conductors at each of the local and remote terminals thereof, said method comprising the steps of:

providing first and second local derived signals representative of an electrical parameter of respectively the first, second, and third phase conductors at the local terminal;
providing first and second remote derived signals representative of an electrical parameter of respectively, the first, second, and third phase conductors at the remote terminal;
transmitting said first and second local derived signals to the remote terminal;
transmitting said first and second remote derived signals to the local terminal;
expanding said first and second local derived signals and said first and second remote derived signals into first, second, and third comparison signals at each of the local and remote terminals;
and logically relating said first, second, and third comparison signals at each of the local and remote terminals to detect the faulted phase conductor and tripping the circuit interrupter on the faulted phase conductor at each of the local and remote terminals.

3 more elements

Dependencies are inferred from the claim text.

Protective relay apparatus and method for providing single-pole tripping

Life of this patent

Protective relay apparatus and method for providing single-pole tripping

Life of this patent

Abstract

Claims38