Abstract: In a switching exchange for circuit-switched/synchronous traffic (CS) and packet-switched/asynchronous data packet traffic (PS), transmission lines communicate with FIFO buffers interconnected by a data bus on which information is transferred in periodic frames. CS traffic is collected in FIFO input buffers in minipackets each carrying a local routing address. The last minipacket per frame period is identified by a special end tag. Once per frame a daisy-chain signal propagates through access control lines to sequentially read out from FIFO input buffers all CS minipackets up to the next one having a special end tag, transferring them through the data bus to FIFO output buffers. Thereafter a token access mechanism starts enabling selective PS data packet transfer between FIFO input and output buffers. When a new frame begins, and PS data packet transfer is interrupted for a CS minipacket readout process, and thereafter transfer of the interrupted PS packet is resumed.

Abstract: The detailed testing of processors, manufactured according to very large scale integration principles, which also extends to secondary functions of operations, such as the setting or non-setting of particular state indicators, necessitates the transfer of large quantities of test data between the processor and the tester, for which purpose no distinction is drawn between external and integrated testers. For testing such structures, the known LSSD method is frequently used wherein the storage elements of the logic subsystems are combined in the form of shift register chains for testing. To permit a fast exchange of test data on the system bus, connecting the processor to a tester, interface register stages are also included in the shift register chain which has a garland-shaped structure and whose beginning and end are connected by a controllable switch during testing.

Abstract: A filter, energized by a polyphase power source, is adapted to detect positive or negative sequence components present in the source. Means are provided for summing a first phase quantity with a second phase quantity which has been shifted by 180 electrical degrees. Additional means are utilized to phase shift the summed resultant itself by 120 electrical degrees and to sum the phase shifted resultant with the phase shifted second quantity and a third quantity. The second summation yields an output quantity proportional to only one of the sequence components, if any, present in the polyphase source.BACKGROUND OF THE INVENTIONThis invention relates to active symmetrical component sequence filter networks and, more particularly, to an economical filter network of such type. In the electrial art, especially that concerned with protective relaying, it is desirable in many instances to detect the presence and magnitude of the positive, negative and zero sequence components of a polyphase power source.

Abstract: Phase comparison relaying apparatus associated with the local and remote end terminals of a protected line section wherein the phase comparison is performed at one terminal by unsupervised circuitry to generate an echo trip signal which is employed to effect breaker tripping at the other terminal. Additional circuitry supervises the generation of a breaker trip signal for use at the terminal where the echo trip signal is generated without preventing generation and transmission of the echo trip signal.The use of such circuitry is described in the operating context of phase comparison relaying apparatus adapted to utilize offset keying. Also described is the effectiveness of such circuitry during open breaker or zero-feed conditions.

Abstract: An improved in-band signal-to-noise ratio monitor is used in conjunction with the receiver of an FSK relaying system. The improved monitor measures the signal-to-noise ratio both prior to and after the receiver input signal is filtered by a narrow bandpass filter. The magnitudes of the measured ratios are compared and, if all signal-to-noise ratio permissives are not satisfied, the tripping function of the relaying system at the receiver or local station is blocked or inhibited.

Abstract: Phase comparison relaying apparatus wherein the keying threshold levels at the local and remote ends of a protected power line section are each offset by a different value from the effective zero axis of the current waveform. One of the keying threshold values is set at a magnitude which will cause a trip response in the presence of low or medium magnitudes of outfeed current. The other keying threshold level is set at a magnitude which will cause a trip response in the presence of maximum magnitudes of expected outfeed current. The upper and lower current margin threshold levels are set to appropriately reflect the keying threshold level with which they are respectively associated. In addition, the transmmitter having the higher keying threshold level is located at that end of the protected line section where outfeed is expected.

Abstract: This application discloses a solid state high output watt transducer which utilizes the pulse width-pulse height multiplication principle and comprises digital integrated circuits for obtaining a direct current output which is proportioned to watts.

Abstract: This disclosure relates to a protective relaying system for a polyphase power transmission line in which at least two separate line operating conditions at a remote end of a protected line section are transmitted to a local end of the line section over a single communication channel. In the preferred illustrated embodiment, the operating conditions of three-line conductors are sequentially transmitted whenever a fault condition is sensed on any one or more of the three-line conductors. During the normal, non-faulted operation, a coded signal is continually transmitted to maintain the time derived signals at the receiver in substantial synchronism with the time derived signals of the transmitter. The coded signal also establishes a trip inhibiting or guard signal at the receiver.

Abstract: The disclosure relates to a time-overcurrent relay utilizing successive linear time-current segments which approximate a non-linear, inverse time-current curve the linear segments are determined by subtracting a series of ramp like voltages of increasing magnitudes from a series of bias voltages, each of which is of substantially constant magnitude and which bias voltage magnitudes decrease in sequence by the peak magnitude of the preceding ramp voltage.

Abstract: A phase comparison relaying network wherein a transmitter keying threshold is set at a predetermined value of the current wave at the transmitter end which is offset from the effective zero axis of the current wave. This yields a signal which, when phase compared with the current wave at the receiver end of the protected line section, permits a tripping response in the presence of "outfeed" current at the "weak feed" end of the protected line section which might occur during an internal fault.

Abstract: This disclosure relates to a segregated phase comparison relaying system which is of the type wherein the current at each end of each of the conductors of a protected section of a three-phase transmission network is phase compared over a communication network for determining whether the fault of the faulted conductor is located within or external to the protected section of the transmission network. Under certain conditions it is desirable to transmit a breaker opening signal from one end (transmitting end) of the protected section to the other end (receiving end) thereof to provide a direct transfer-trip at the receiving end in response to the detection at the transmitting end of a fault which might not cause the breaker at the receiving end to open when using the segregated phase comparing system.

Abstract: A backup control system for a gas turbine power plant having a computer implemented primary control system is disclosed. Bumpless transfer between the two control systems is effected by tracking a plurality of control signals generated by each control system, the signals being functionally identical, but independent. After comparison of the functionally identical signals, transfer between the two control systems is permitted only if any tracking error does not exceed a permissible deadband margin.The presence of tracking error is also utilized to generate a signal which is employed to operate panel mounted signal means, which panel can thereby be used as a diagnostic tool in monitoring the health of both the primary and backup systems. Transfer reliability is thereby enhanced and turbine availability improved.

Abstract: A local maintenance controller permits continued power generation during maintenance or failure of a primary gas turbine control system by manually for maintenance purposes or automatically for failure purposes assuming turbine control to thereby insure continued operation. The local maintenance controller set forth is particularly suitable for use in conjunction with a computer implemented gas turbine control system.Transfer between the local maintenance controller and the primary control system is effected in a bumpless manner so that load swings are absent. However, if the turbine was operating at system reserve at the time of transfer, the local maintenance controller reduces the load to peak value until primary control is resumed. Operation at any other load at the time of transfer is maintained by the controller. Transfer back to primary control is also effected in a bumpless manner.

Abstract: A combined cycle electric power plant including gas and steam turbines, steam generators, afterburners and a digital/analog control system is provided with inlet guide vane control apparatus adapted to match gas turbine exhaust flow to the requirements of the steam generator with which it is associated. The guide vane control apparatus operates to limit the inlet guide vane position as a function of gas turbine compressor inlet temperature in accordance with a desired gas turbine exhaust flow at predetermined operating conditions.

Abstract: A combined cycle electric power generating plant, which includes gas and steam turbines, inlet guide vane positioning means for the gas turbines, steam generators, afterburners and a digital/analog control system, is provided with inlet guide vane control apparatus adapted to modulate the position of the inlet guide vanes as a function of load or inlet blade path temperature. The inlet guide vane control apparatus is further adapted to operate in either an automatic or manual mode with additional provision for bumpless transfer therebetween incorporated in the control apparatus.

Abstract: This disclosure relates to phase comparison relaying systems for a three phase power transmission line in which the current is measured at each end of each phase conductor. The phasor difference of the currents in a selected two of the phase conductors is determined at each end of the selected conductors and is phase compared to determine the location of phase-to-phase faults whether or not a ground fault is involved while the phasor sum of the current in all three of the phase conductors is determined at each end of the phase conductors and is phase compared to determine the location of phase-to-ground faults.

Abstract: A gas turbine power plant is provided with an industrial gas turbine which drives a generator coupled to a power system through a breaker. The turbine-generator plant is operated by a hybrid control system having digital function capability during sequenced startup, synchronizing, load buildup and steady state load, and shutdown operations. The control system also contains monitoring and protective subsystems which function through all stages of operation, with redundancy and permissive features which maximize turbine availability.

Abstract: An automatic control system for high pressure blower applications prevents surging under variable supply flow rate requirements and achieves maximum efficiency of operation. The supply flow rate establishes the set point of a proportional plus reset controller, the latter receiving a feedback signal corresponding to the static discharge pressure of the supply blower and responding thereto for controlling the output of the supply blower. A return blower is controlled either through a characterizer relay in proportion to the control of the supply blower to maintain a fixed precalibrated relationship between supply and return flow rates or by a further proportional plus reset controller responsive to the supply flow rate, for establishing the set point thereof, and to the return flow rate, as a feedback signal thereto, for controlling the output of the return blower.