Abstract: A generating system including a permanent magnet generator having a stator, a rotor journalled for rotation in proximity to the stator and normally separated therefrom by a small air gap. Permanent magnets and windings are provided on the stator and the rotor respectively, or the reverse as desired and a detector is provided for sensing the development of an electrical fault in the winding and for moving the stator away from the rotor to increase the air gap thereby reducing the magneto motive force available to induce current in the winding to prevent burn out of the winding.

Abstract: A protective relay having an operational boundary matched substantially to the output performance limit characteristics of a generator to enhance the protection. The protective relay generates a signal representative of a discriminating impedance based on measurements of the generator's terminal voltage and current. The relay utilizes two pairs of predetermined values which characterize in part the generator's output performance limit curves. Two corresponding pairs of vector signals are generated by the relay based on their respectively corresponding pairs of predetermined values and the generated discriminating impedance signal. The angles between the vector pairs are measured by the relay and are compared with predetermined angle values which also represent in part the generator's output performance limitations. Leading and lagging conditions of at least one of the vector pairs affects the selection of the predetermined angle value used in the comparison with the measured angle associated therewith.

Abstract: A malfunction detector for detecting an open-circuit condition at the output terminal of a vehicular DC generator is disclosed. The frequency of a signal derived from one of the armature windings of the generator, for instance, at an end or neutral terminal, is compared with the control frequency of the voltage regulator, which may be derived from a field winding of the generator. If the latter is equal to the former, an indication of an open-circuit condition is given.

Abstract: A microcomputer implemented apparatus and method for detecting the occurrence of a shorted diode in the rotating rectifier of a brushless alternator. The alternator current, voltage and power output and the alternator temperature are measured. The anticipated exciter field current is determined for the alternator output and operating conditions and compared with the actual exciter field current. An actual exciter field current in excess of the anticipated current indicates a rectifier fault.

Abstract: A charging generator system including a protective circuit which prevents the generator system from overheating when the ambient temperature is extraordinarily high. A protective shorting circuit is coupled between a rectifier output terminal supplying the field coil of the generator and the ground terminal. The protective shorting circuit has a high resistance for normal temperatures and a low resistance for high temperatures, thereby to interrupt the current flow in the field coil when high temperatures occur. In one embodiment, the protective shorting circuit means is implemented with a single thermistor. In another embodiment, a protective transistor is coupled to the field coil, and base current is supplied to the protective transistor when the temperature rises above a predetermined level to thereby shut off the current flow through the field coil under such conditions.

Abstract: An apparatus for detecting a ground fault occurring in a power system which furnishes an AC power from a variable-voltage variable-frequency power supply to a load via a voltage transformer. The apparatus compares a zero phase sequence current with a reference value and, upon detection of occurrence of a ground fault, produces an output signal representing the ground fault. Prior to such comparison, the zero phase sequence current is so processed as to be independent of the frequency of the power system or the reference value is so processed as to be dependent on the said frequency.

Abstract: In case of short circuit the overcurrent which passes through a detecting resistance in series with the excitation winding of the alternator operates a threshold current generator, which reduces the voltage of the central node of a voltage divider. A trigger interposed between said central node and an actuator circuit (for example a Darlington circuit) placed in series with the excitation winding of the alternator and with the above mentioned resistance turns off said actuator circuit, thus interrupting the current passage through the excitation winding. A filtering condenser associated to the voltage divider restores with delay the initial condition. The cycle is periodically repeated until the short circuit condition remains.

Abstract: A charging generator controlling device including a protective circuit for protecting against excess current flow due to a short circuit. The device includes a charging generator, a rectifier, a battery, a voltage regulator circuit, a charge display lamp, a load and a current path switching device, as in a conventional device. The protective circuit includes an excess current detecting transistor coupled to be rendered conductive when the current flowing from the battery through the keyswitch to the field coil of the charging generator exceeds a predetermined value, in which case current is supplied from the battery through the keyswitch to a capacitor connected in a discharge loop. A comparator generates an output which drives a current switching device to energize the charge display lamp instead of the load and render a transistor series-connected with the field coil nonconductive during a predetermined period when the voltage across the capacitor exceeds a predetermined value.

Abstract: A circuit for detecting the occurrence of a shorted diode in the rotating rectifier of a brushless alternator. A sensing circuit is responsive to the direction of current flow through the exciter field winding. A reversal of the current indicates that there is a shorted rectifier diode.

Abstract: A short detection circuit and method for operatively controlling current in an electrical load such as an alternator field coil includes a driving device such as a Darlington transistor for driving the electrical load. Detecting means selectively withhold and provide operating current to the driving means when a shorted and not shorted condition of the electrical load is respectively detected at the driven terminal of the driving device.

Abstract: A protective circuit for reducing subsynchronous natural resonant frequency signals in a multiphase power supply system includes a damping resistor connected in series with each phase winding of the system. A resonant circuit tuned to the rated line frequency of the system is connected in parallel with each resistor so that signals having frequencies other than the rated line frequency will be damped by the resistors. An inductor can also be placed in parallel with each resistor to maximize the damping effect of each resistor at predetermined subsynchronous frequencies.

Abstract: An improved charging generator controlling circuit which is capable of detecting failures which could not be detected with prior art such circuits, thereby providing greater security of the electrical system in the vehicle in which the circuit is employed. A full-wave rectifier rectifies the AC output of the armature coils of the generator, the rectifier including first and second rectifier output terminals and a ground terminal. The field coil is coupled to be excited by the output provided at the second rectifier output terminal of the rectifier. A battery is coupled to an output provided at the first rectifier output terminal of the rectifier to be charged thereby. A voltage regulator controls the application of exciting current to the field coil, thereby to maintain the output voltage from the generator at a first predetermined value. A charge display lamp is connected through a keyswitch between the battery and the ground terminal.

Abstract: An electrical distribution system has parallel connected generators powered by variable speed engines. Loads connected with each generator are interconnected through an electrical distribution bus. Constant speed drives have inputs connected with the engines and outputs directly connected with the generators. The connections between the constant speed drive outputs and the generators are characterized by the absence of overrunning clutches used in prior systems. An improved electrical protective circuit senses a flow of electrical power from the distribution bus to a generator, driving the generator as a motor. If the power flow to the generator is excessive, the bus tie breaker is opened disconnecting the generator from the bus.

Abstract: A motor driven generator has a generator control unit which incorporates a programmed microprocessor to control generator operation. A generator voltage regulator utilizes the microprocessor of the generator control unit to develop an error voltage which is added to the average phase voltage of the generator, controlling the generator field current. In the event of a phase failure the generator control unit senses an abnormally high phase voltage condition, disables the average phase voltage circuit. In the event of an abnormal difference between the high and low phase voltages, the gain of the error signal circuit is reduced.

Abstract: A protective relay for protecting a power system from sub-synchronous current oscillations. The protective relay determines both the amplitude and frequency of sub-synchronous current oscillations occurring in the power system. A series of logic relationships, based in part on the parameters of the power system, are implemented by the protective relay such that when the frequency and amplitude of the sub-synchronous oscillation signal satisfy these relationships a trip signal is produced.

Abstract: The protection system includes an over-temperature warning lamp in addition to the usual charge indicator lamp. Both lamps light at ignition as a test, then both go out. If the alternator should fail, both lamps again light. If the alternator overheats, only the warning lamp is lighted and current to the field coil is removed.

Abstract: The input signal corresponding to the respective frequency or power variation is supplied both to the inputs of the discrete filters and to angle measuring devices assigned to them, of which only the tuned filter in conjunction with its angle measuring device actuates a switch which sends the filter output via angle rotating and matching elements to a MAX selector element, from which the supplementary damping signal for the excitation is tapped. For low oscillation frequencies a low-press filter is provided which, via mean value formers and time delay multivibrator stages, permits a regulator signal to become operative for the excitation, delayed or undelayed, when certain limit values are exceeded.

Abstract: A system for supplying power to a field winding to maintain excitation of an alternating current generator during excessive output current conditions, the generator having a plurality of output lines for supplying power to a load and the field winding being supplied during normal operating conditions by a shunt type voltage regulator responsive to the output voltage of the generator. The system includes a current transformer having a primary winding in series with an output line of the generator, a secondary winding, and a tertiary winding shunted by a capacitance. A rectifier circuit rectifies the voltage supplied by the secondary winding, the output terminals of the rectifier circuit being connected in series with the regulator output terminals to supply power to the field winding. A control circuit, connected to the output of the generator and responsive to output current conditions enables the rectifier circuit output during excessive output conditions.

Abstract: A device for detecting current imbalance between phases of a polyphase alternating current generator. A detector responds to the maximum peak current in the generator, and detecting means generates an output for each phase proportional to the peak current of each phase. Comparing means generates an output when the maximum peak current exceeds the phase peak current.

Abstract: A circuit for damping hunting oscillations of controlled electric machines. The circuit is provided with a measuring circuit for determining the hunting oscillations and an identifier circuit for determining the angle components of such hunting oscillations. A phase shifter circuit is provided for receiving the angle components produced by the identifier circuit and forming a hunting oscillation correction signal which is shifted in phase from the hunting oscillations by a predetermined phase angle. The hunting oscillation correction signal is conducted to a control unit of the electric machine. The invention is particularly useful in damping hunting by the rotors of voltage controlled synchronous generators.

Abstract: A voltage source is connected in series with the neutral secondary winding on a generator step-up transformer through an electrical reactance. A control circuit and a pair of thyristor banks are employed to apply the voltage source to the transformer winding to dampen sybsynchronous resonance currents and to prevent torsional mode vibrations from occurring within the generator.

Abstract: For damping torsional oscillations of an electric a.c. generator, a speed-sensing member, for example a tachometer-generator, is connected to the a.c. generator. The speed-dependent signal generated by the speed-sensing member is supplied to a band-pass filter which is adapted to the natural frequency of the torsional oscillations. The output signal of the band pass filter is supplied directly to the control angle determining means of a converter connected to the generator. In this way, the power of the converter is modulated in such a way that the oscillations are damped.

Abstract: There is disclosed a system for predicting desynchronization of a synchronous machine by detecting a phenomenon of radical variation of the magnetic flux in the gap of a synchronous machine immediately before falling in an asynchronous state. For example, a functional value of the fundamental harmonic component and that of the higher harmonic component of the flux in the gap are detected for comparing the variation of each functional value with a predetermined reference level to predict desynchronization of the synchronous machine.

Abstract: Apparatus is disclosed for continuously monitoring the air gap torque acting on the rotor of a 3-phase electrical generator by sensing certain of the output voltages and currents produced by the generator as it supplies power to a connected load. In a preferred form of the invention, signals representing the three generator output voltages and two of the three line currents are conditioned and combined in electrical circuitry to produce a single output signal which is indicative of the air gap torque. The torque signal so produced is in a form easily handled by conventional means such as computers and recorders, and is appropriate for use by operating personnel in making decisions regarding generator operation.

Abstract: A shaft torsional oscillation signal of a rotatable torsional system including a rotor of a synchronous machine, at least one rotatable body and a shaft coupling the synchronous machine and the rotatable body, is detected. The shaft torsional oscillation signal with a specific frequency is made to advance the phase thereof by a stabilizing control device. The field voltage of the synchronous machine is so controlled that a sub-synchronous resonance (SSR) of the rotatable torsional system caused by the specific frequency is restrictedly controlled by the shaft torsional signal of the specific frequency phase-advanced.

Abstract: Voltage, current and field voltage of a generator connected to an electric power system are sampled at a predetermined period for analog-digital conversion and then led to a digital computer. In addition to computation for AVR, the computer computes from its input the generator output power, and also monitors the occurrence of a fault, the removal of the fault and variation in the generator output in the system. After the occurrence of a fault, the field excitation of the generator is intensified until the generator output power reaches substantially a peak value, but after the peak value is substantially passed by, the excitation is conversely depressed to a value below the level which is present before the fault occurs. When the generator output power recovers the value which is present before the fault occurs, the computer returns to deliver the AVR output.

Abstract: A generation control apparatus for a vehicle generator detects the output voltage of an excitation current supplying rectifier circuit of the generator. When the output voltage is lower than a predetermined value, a switching element is turned on and a current for operating an indicator lamp is caused to flow through a resistor connected to the switching element, thus detecting a break in the generator circuit.

Abstract: Apparatus and method for monitoring torsional vibration in the rotor of a dynamoelectric machine by detecting electrical quantities available at the output terminals of the machine. For at least one phase of the machine, output voltage and current are detected and a composite signal is formed therefrom in signal processing circuitry. The composite signal is in synchronous phase with the mechanical angle of the rotor and may be demodulated to obtain the torsional vibration information.

Abstract: A motor vehicle battery charging installation includes an alternator/rectifier combination which is controlled by a voltage regulator and is connected to the battery. A warning lamp is connected in series with the collector-emitter of a control transistor across the battery. The voltage at the base of the control transistor is determined by a resistor/capacitor/diode network connected to the rectifier output and to a phase point of the alternator to turn the lamp on whereas the alternator is producing no output. A zener diode is connected to the rectifier output and to an auxiliary input of the regulator to take control should the connection between the alternator and the battery become interrupted. Current flow through this zener diode is detected by a second transistor with its collector-emitter parallel with the first-mentioned transistor so as overridingly to illuminate the lamp in the event of the zener diode becoming conductive.

Abstract: In a generating system having a shunt-type regulator for exciting the field of a generator during normal operating conditions, circuitry is provided for supplying voltage to a field winding to maintain excitation of the generator during excessive output current conditions. This circuitry senses the low voltage indicative of a fault or overload condition and in response boosts the field of the field winding during such an excessive output current condition an amount sufficient to maintain generator excitation during that particular condition. It does this by impressing a voltage, supplemental to that supplied by the regulator, upon the field winding during the condition. As a result the excitation of the generator is maintained.

Abstract: A corona discharge monitor system for a dynamoelectric machine, particularly for large salient pole generators, has an antenna mounted on a rotor pole. The antenna sweeps over the stator slots and picks up radio frequency signals produced by corona activity occurring in the structure of the stator bars. A rotary coupler, having a rotating portion fixed to the shaft of the machine and a fixed portion adjacent to the rotating portion, couples the signal to a signal conditioner. A trigger signal synchronized with the rotor rotation and with a known reference to antenna position and derived from the power system line frequency, is used as one input to a storage device such as a variable persistence oscilloscope. A first output of the signal conditioner represents the peak amplitude of the corona discharge and a second output represents the number of corona occurrences and these are applied to the storage device.

Abstract: A power angle relay to measure the power angle of a synchronous alternator. The power angle relay receives a reference voltage signal corresponding to a fixed point on a reference voltage waveform (usually a zero crossing) from some point in the power system to which the alternator is normally synchronized and an electric signal representative of the angular position of the shaft of the synchronous alternator and is operable to combine the two to provide an indication representative of the power angle between the direct axis of the synchronous alternator and said fixed point.

Abstract: A method, and apparatus for, protecting an object, and specifically detecting ground shorts in the rotor circuit of a generator, wherein for essentially completely detecting a ground short the phase of an alternating signal is modulated to produce an alternating injection or test signal which is delivered to the object to be protected, i.e. the rotor circuit. A response signal corresponding to the injection signal and indicative of the ground short is derived from the rotor circuit. The modulated alternating signal may be at the network frequency and modulation of the phase thereon preferably encompasses continuously switching the phase of the alternating signal between two phase positions in the sense of a phase oscillation. The alternating signal is preferably in the form of an alternating voltage.

Abstract: A protective device for a brushless exciting device comprises: a signal transmitter for transmitting a signal that is applied between a neutral point of an armature winding of an AC exciting device and ground; a signal detecting circuit for detecting the signal transmitted from the signal transmitter; a signal comparator circuit for comparing the frequency of the signal taken from the signal detecting circuit with a predetermined frequency value to output a signal indicating the difference between them; and an abnormal fault detecting device which detects an abnormal fault in the output signal from the comparator and accordingly outputs a signal for the abnormal fault or indicates directly the abnormal fault. The abnormal fault detecting device may compare a pattern of the difference signal from the signal comparator circuit with predetermined signal patterns for various faults.

Abstract: A stabilizing equipment for a power transmission system having a power source system, at least one transmission line and at least one line circuit breaker inserted between the power source system and the transmission line for interrupting the transmission line when a fault occurs thereon. The stabilizing equipment comprises a fault detector for detecting the fault, a series damping resistor, first means for inserting the series damping resistor between the power source system and the line circuit breaker before the line circuit breaker is opened and after the fault is detected by the fault detector, a parallel damping resistor, second means for inserting the parallel damping resistor between the power source system and ground after the line circuit breaker is opened, and third means for separating the parallel damping resistor first and subsequently the series damping resistor before the line circuit breaker is reclosed after reclosing conditions are satisfied.

Abstract: Protective relay apparatus which includes monitoring and detecting functions related to subsynchronous currents in a three-phase electrical power system. The monitoring function provides signals related to the positive sequence component of any subsynchronous current flowing at a monitored subsynchronous frequency. The detecting function is responsive to the signals provided by the monitoring function, distinguishing between subsynchronous currents due to self-excited oscillations, and those due to transient oscillations, to provide a timely trip signal for a circuit breaker in either instance.

Abstract: For detecting electrical overloads in a traction vehicle propulsion system wherein the output of a prime mover-driven electric generator is controlled by varying the on-off duty cycle of an intermittently conductive switch connected in series with a field winding of the generator excitation means, monitoring means is connected across the field switch to produce an output signal in response to the field switch being continuously conductive for an abnormally long period of time which is indicative of an over-excited condition.

Abstract: A resistor, a DC source and a current converter are connected in series between one terminal of the field winding and the ground. When a ground fault occurs on the field winding, it is detected by the output of a voltage detector connected across the resistor or the output of the current converter, and an alarm device is operated. At the same time, another resistor is connected between the other terminal of the field winding and the current converter through a switch, and the magnitude of the ground fault is calculated by the outputs of the voltage detector and of the current converter before and after closure of the switch. When the magnitude of the ground fault is large the generator is disconnected.

Abstract: A machine and method for destroying plant growth. A specialty application is provided for plant growth around and between railroad tracks, and a general description is provided for preventing damage to the high voltage source of electricity used for the plant destruction, and for minimizing the number of fires started in dry material accessory to plant destruction. A vehicle with a high voltage electricity source is mounted on railroad tracks, with wheels of each wheel set for the vehicle being electrically isolated, and the high voltage source being grounded through one of the wheels. Special plant contacting devices comprising rounded end generally cylindrical contacting members are provided. The current output of the high voltage source is limited to prevent damage to the high voltage source, and the no-load voltage of the high voltage source is held to generally the same level as the full-load current limited voltage to minimize the number of fires started by the plant contactors.

Abstract: A multiphase to single phase electrical energy converter wherein the frequency is converted from a relatively high frequency, in order of 1,000 hertz, to a relatively low frequency, as for example, normal household frequency of 60 hertz. A three-phase alternator is driven by an internal combustion engine, the output of the alternator being fed to a full-wave bridge circuit and finally to an inverter. The output of the bridge circuit is acted on by a resolver. The resolver is utilized to control the delivery of energy from the alternator to the inverter to provide an average current or power to the inverter which increases and decreases in a unipolar sinusoidal form at a frequency which is twice the desired output frequency. The inverter is utilized to invert every other cycle of the output from the resolver. Thus, the power from the inverter will take the form of an alternating sinusoidal waveform at 60 hertz.

Abstract: Apparatus is described for monitoring arcing of brushes used in the transfer of current signals to and from the field of a generator. Electrical signals from the brushes, which are applied to the disclosed monitor for analysis, may include brush arcing signals to be monitored and in addition high-amplitude noise spikes in the same frequency band as the brush arcing signals, the noise spikes thus masking accurate detection of low level brush arcing by conventional devices. A two-stage clipping network is provided in the monitor to raise the brush arcing/noise ratio and thus mitigate the masking effect of the noise spikes without loss of a portion of sampling interval during which arcing may occur.

Abstract: A generator set includes a main generator, a permanent magnet pilot alternator, a rectifier assembly connecting the pilot alternator output to first and second supply rails, a relay having a contact, and a regulator for the main generator having a semi-conductor output element, the output element, the field winding and the contact being connected in series between the first and second supply rails. A power supply circuit is transformer coupled to the pilot alternator and provides a stabilized power supply both for the regulator and the relay, such power supply circuit having an earthed terminal. A resistor is connected between the second supply rail and the earth terminal, so as to limit fault current in the event of an earth fault in the connection between the contact and the field winding.

Abstract: Thyristors are substituted for conventional diodes in the rotating rectifier assembly of a brushless exciter in a synchronous dynamoelectric machine. In contrast with prior systems in which thyristors are switched at relatively high ceiling voltages (requiring thyristors of high power rating and additional components for fast de-excitation), the gates of the thyristors in the present invention are fired only at a low voltage point of the negative half cycle of the polyphase armature voltage waveforms for fast de-excitation and are maintained in a fully conducting condition during the positive half cycle. This permits the use of thyristors having a relatively lower power rating and makes unnecessary additional components to achieve fast de-excitation.

Abstract: A method of, and apparatus for, protecting electrical devices, such as generators connected in parallel against ground faults or shorts, wherein when there arises a ground short at one of the parallely connected generators a ground or earth current (response signal) flows between the fault location and a ground location. The network is grounded at the ground location by means of a ground transformer and a ground resistance. In order to essentially completely detect the ground short the phase of an alternating signal is modulated to produce an alternating injection or test signal which is delivered to the network containing the parallely connected generators. A response signal corresponding to the injection signal and indicative of the ground short is derived from the electrical network.

Abstract: In a series capacitor transmission system the protective bypass device has a force firing arrangement responsive to an applied signal for causing the series capacitor bank to be bypassed rapidly, such as within three cycles, for reducing subsynchronous oscillation effects on generating equipment connected with the transmission system. A capacitive potential device supplies power to energize a firing control circuit with a pulse transformer placing high frequency or pulse voltage across the protective device for rapid bypassing. The bypass device may be a protective spark gap as is normally present for protection of the capacitor bank against overvoltages.

Abstract: A system for protecting a turbine-generator power plant governed by signals representative of turbine mechanical power and generator electrical power to reduce at times the turbine mechanical power, with an electronic filter included therein for the purposes of filtering a periodic time varying component of the electrical power signal having a response time within adequate protective limits, is disclosed. More specifically, the electronic filter generates a train of fixed time durations wherein during each fixed time duration the maximum and minimum amplitudes of the electrical power signal are selected. A signal is sampled at the end of each fixed time duration and held constant for each next fixed time duration, said signal being representative of the average of the maximum and minimum amplitudes selected during each fixed time duration.

Abstract: Power system stabilizers are used in the excitation systems of large shaft driven synchronous dynamoelectric machines for the purpose of enhancing the dynamic stability of power generating systems. Such stabilizers using speed, power or frequency as an input signal when applied with high initial response excitation systems are effective in damping low-frequency local or inter-tie mode oscillations which may occur in the system. The power system stabilizer may adversely affect torsional damping at higher frequencies. The adverse effects of a power system stabilizer at shaft torsional frequencies are obviated by providing a torsional oscillation protection device comprising a composite band-reject filter of the present invention which attenuates the power system stabilizer output at the shaft natural torsional frequencies without introducing an excessive phase lag at the local or inter-tie mode frequencies.

Abstract: An electrical generator arrangement includes a variable-ratio drive device, an alternator driven by the drive device and a generator which is separately excited by the alternator output. An over-running clutch connects the alternator and generator rotors so that in the event of an alteration in the driving output from the drive device the generator can continue to rotate with its normal speed and direction but the frequency of the alternator output provides an indication of the operating state of the drive device.

Abstract: A method and apparatus for reducing the mechanical stresses on the shaft of a turboset and on the shaft of the generator coupled thereto upon the occurrence of a three-pole mains short circuit near the generator and upon the subsequent elimination of the three-pole short circuit. A generator switch is connected between the output of the generator and the mains, and a resistor, whose size is adapted to the size of the load on the generator, is connected in parallel with the generator switch. The generator switch is opened upon the occurrence of a short circuit to switch the resistor into the load circuit of the generator and the resistor is again bridged when the short circuit is switched off of the mains.