Abstract: The generator includes an asynchronous machine with a wound rotor driven mechanically and a stator connected to the network. The rotor is excited by a constant DC voltage source via an inverter controlled by a pulse width modulation control circuit. In accordance with the invention, the following are generated: a stator frequency set point, a rotor frequency set point which is a function of the stator frequency set point and the rotation speed of the machine, an rms stator voltage set point, an error signal which is a function of the difference between the rms stator voltage set point and the actual rms stator voltage. A rotor voltage set point is imposed on the control circuit which is a function of the error signal and the rotor frequency set point.

Abstract: A method is provided for regulating a three-phase machine functioning under any operational conditions without a mechanical rotary transducer. The machine is supplied with D.C. power by an inverter, where parameters of a D.C. link using an actual switching state of the inverter are detected for regulation. The method includes measuring (1) flow direction required for field-oriented control in asynchronous machines, and (2) rotor position for rotor-oriented control in synchronous machines. The measuring is performed by using spatial magnetic conductivity fluctuations in the machine. The conductivity fluctuations are detected using parameters for a D.C. link. An actual switching state of an inverter is used in the measuring process. Mathematical evaluation to calculate flow direction or rotor direction is then performed.

Abstract: Shift means shifts a rotation speed range to a low rotation speed side based on an electricity amount related to rotation speed. In the rotation speed range, driving torque of a generator is suddenly changes as a result of an increase of duty ratio of a switch due to a shortage of generation capacity caused by a reduction of a rotation speed of a vehicle alternator. Preferably, the shift means shifts the rotation speed range to the low rotation speed side by changing the adjust voltage based on the electricity amount related to rotation speed while the rotation speed is reduced.

Abstract: A generator control unit (200) includes a field current modulator (212) that repeatedly switches between an ON state and an OFF state to control the flow of field current to the generator (20), a free-wheeling path (216) that feeds excitation current from the generator (20) back to the generator (20) as a field current component when the field current modulator (212) is in the OFF state, and an impedance circuit (220) that selectively and temporarily absorbs excitation current in the free-wheeling path (216) to reduce voltage overshoot of the generator (20) upon occurrence of an operating transition, such as a transition from high load to low load. In one implementation, the impedance circuit (220) is an RC circuit and a by-pass switch (222) is provided across the RC circuit. When excitation current in the free-wheeling path (216) is not to be absorbed by the RC circuit, the by-pass switch (222) is ON, thereby providing a lowe impedance path for the excitation current.

Abstract: A control voltage is set to an acceleration control voltage which is higher than a battery voltage V by a predetermined voltage difference &Dgr;V1 within a range and delayed by a predetermined time &Dgr;T1 during acceleration at low speeds. During acceleration at low speeds, the rotational speed is less than a predetermined value and the rate of increase in rotational speed is equal to or greater than another predetermined value. The range of voltage is higher than battery voltage V and lower than the steady state control voltage of 14.5V.

Abstract: An electrical system for a turbine/alternator comprising a gas driven turbine and permanent magnet alternator rotating on a common shaft comprises an inverter circuit connectable either to an AC output circuit or the stator winding of the alternator. A control circuit during a startup mode switches the inverter circuit to the stator winding of the alternator and during a power out mode switches the inverter circuit to the AC output circuit. Thus, during the startup mode, the alternator functions as a motor to raise the speed of the turbine to a safe ignition speed and in the power out mode the electrical system outputs to the AC output circuit, electrical power having a frequency unrelated to the rotational speed of the alternator.

Abstract: A controlled rectifier bridge for a generator having a plurality of phase windings and one exciter winding is constructed as a self-controlled rectifier bridge with MOS field effect transistor. To allow the use of such a rectifier bridge upon a fast load reduction with an attendant load-dump voltage, a voltage protection circuit is employed that feeds the energy, stored in the exciter winding upon a fast shutoff, back into the battery, thus deexciting the exciter winding. Upon a fast load reduction, the generator windings are short-circuited by suitable triggering of the low- or high-side transistors.

Abstract: An excitation apparatus for a generator includes an AC/AC inverter having a voltage holding function and connected to an output line of an AC generator. The apparatus includes an AC/DC converter, a capacitor connected to an output of the AC/DC converter, and a DC/AC converter connected to the capacitor and excites a field winding of the generator with an AC/DC converter controllable with a current and connected to the output of the AC/AC inverter. Even when a voltage of the output line is lowered due to a failure in a system, since energy stored in the capacitor is discharged and the voltage is maintained for the time being, the excitation current of the generator can be kept at a sufficiently high value.

Abstract: A synchronous generator is disclosed having main power windings and auxiliary power windings, where the auxiliary power winding is coupled to a variable frequency drive system. The variable frequency drive causes the generator to function as a motor and turn a drive shaft to start a gas turbine. Switching circuits are used to connect and disconnect the auxiliary windings of the generator with the variable frequency power supply.

Abstract: A method for regulating a generator is described in which the rectified output voltage furnished by the generator is converted, under certain preconditions, with the aid of a direct voltage converter. The generator can be operated either in a free operating mode or a regulated operating mode. If the generator voltage output in the particular operating state is not equivalent to the on-board electrical voltage, then the generator voltage is either raised or lowered with the aid of the voltage converter. The selection of the generator operating mode is done as a function of rpm or voltage, in such a way that the available generator power or energy conversion efficiency is as high as possible.

Abstract: An alternator generates output power at two or more independent voltages. The alternator has two independent output windings configured to generate the power needed for each output. Each output voltage is sensed by a regulator that controls switching rectifiers to supply the current needed to satisfy the electric power demand of the loads connected to each output. After both output load demands are satisfied, the regulator switches off the alternator field. When power demand from either load rises, the alternator field is switched on along with the respective switching rectifier to satisfy the power demand. The output voltage grounds and control signals may be electrically isolated from each other.

Abstract: A control system for a variable frequency generator is disclosed of the type having a main stator winding for providing a generator output, excited by a main rotor winding, and a main exciter rotor winding for energizing the main rotor winding, excited by a main exciter field winding, the control system having:

Abstract: An excitation controller sets an output terminal reference voltage of a synchronous machine from a reactive current output from the synchronous machine and a high side reference voltage of a transformer, and controls the field current supplied to the field winding of the synchronous machine in response to the deviation between the reference voltage and the output terminal voltage. Although a conventional excitation controller can maintain the transmission voltage on the transmission bus at a fixed value, an expensive potential detector is needed for detecting the transmission voltage on the transmission bus, which increases the manufacturing cost of the excitation controller.

Abstract: An excitation control system for a generator includes an SCR bridge for providing an excitation voltage to the input of the generator; a regulator for regulating the excitation voltage; and a sensing sub-system for providing an electrical signal, such a generator current or generator watts, which is related to the output of the generator. The generator includes a circuit breaker for the one or more alternating current phases output by the generator. An output of the circuit breaker has a signal with a true state when the circuit breaker is closed and the generator is on-line and with a false state when the circuit breaker is open and the generator is off-line. A comparator provides a validation signal when the generator electrical signal is greater than a predetermined signal, such as minimum generator current or minimum generator watts, respectively. An OR gate qualifies the signal of the output of the circuit breaker with the validation signal and provides a qualified signal therefrom.

Abstract: An excitation control system for a generator includes a silicon controlled rectifier bridge having an input interconnected with a plurality of alternating current (AC) phases of positive and negative polarity, an output interconnected with the field input of the generator in order to provide an excitation voltage thereto, and an SCR segment for each of the positive and negative polarities of the AC phases. Each of the SCR segments has an SCR responsive to a control signal in order to control current conduction within the segment between the input and the output of the SCR bridge. A regulator circuit requests a maximum value of the excitation voltage for the generator. The auxiliary contacts of a generator circuit breaker determine when the generator is on-line and connected to a power circuit. A phase lock loop provides an error signal from the AC phases. A control circuit outputs control signals to the SCR segments in order to control current conduction within the segments.

Abstract: Apparatus for adjusting the terminal voltage of a single phase alternator employs a current sensor for sensing the load current. The load current signal is compared with a set point for producing an accelerator signal as the load changes. A drive for the alternator is controlled by an accelerator responsive to the accelerator signal. When the system is in a no load condition, the accelerator signal reduces the speed of the drive. A circuit responsive to the terminal voltage drives an exciter circuit to maintain the terminal voltage at not less than 50% of a desired or rated voltage.

Abstract: Circuit configuration for degradation of the stored magnetic energy of a field winding of a generator, where a battery voltage is applied to the field winding, having a power switch that is in operative connection with the field winding and is controllable by timed pulses from a clock control and which controls the storage and degradation of energy of the field winding. A zener diode is arranged between the field winding and a control input of a power switch for control of the energy degradation of the field winding, in particular of the power switch.

Abstract: An AC generator whose field winding (4) on the rotor is excited by AC so that the resultant speed of the rotating field is the algebraic sum of the rotor speed and the speed of the field relative to the rotor itself. This makes it possible to generate AC at a frequency different from that of conventional DC excited generators by the appropriate choice of the frequency of the AC input to the rotor field circuit. It enables the stabilization of the output frequency of the alternator when speed changes occur, by the adjustment of the AC frequency of the rotor input. The AC fed to the rotor is from an auxiliary winding (3) which may be housed on the rotor itself, thereby eliminating the need for any brushes or slip rings. The AC is induced in the auxiliary rotor winding by having an auxiliary winding on the stator (2), distinct from the main stator winding (1). The input to the stator auxiliary winding may be from an inverter (5) whose frequency may be adjustable.

Abstract: An apparatus for limiting a peak voltage of a generator provides an auxiliary winding within the stationary exciter filed magnetic structure. The auxiliary winding is coupled to a controllable current source that provides a current to the auxiliary winding based upon an operating speed of the generator. The current flow is effective for moving the quiescent flux bias point of the exciter field magnetic structure for limiting the peak voltage for any operating speed of the generator.

Abstract: A power device including a magneto and a rectification circuit for rectifying an output of the magneto is provided which is capable of adjusting an output of the magneto without any specific control circuit. A field adjusting excitation coil is arranged on a side of a stator of the magneto so as to generate a field adjusting magnetic flux when it is excited, resulting in a magnet field of the magneto being varied by means of the magnetic flux. The field adjusting excitation coil is connected to an intermediate portion of a current flow circuit for a load current, to thereby be excited by the load current, so that a magnet field of a rotor of the magneto is varied depending on the load current, leading to adjustment of an output of the magneto.

Abstract: A voltage controller for a three-phase generator is disclosed in which the phase voltage of the generator is evaluated. This phase voltage is evaluated with the aid of a window comparator with variable thresholds. Via a VCL signal, which switches over each time a threshold adaptation occurs, a frequency-dependent signal can be generated that can be evaluated as a measure for the generator rpm.

Abstract: A control device for a motor vehicle electric generator takes into account the relationship between field currents flowing through field windings of charging generators having different generation powers and output currents. The field current is increased once and instantly at the time of loading but prior to suppressing the increasing speed of the field current. The amount of the increase of the field current is controlled to be proportional to the field current before the loading. The control device according to the invention can be used for charging generators having different power generation capacities, and the battery voltage drops at the moment when switching in a motor vehicle electric load are reduced to substantially the same level.

Abstract: In a power control system for a vehicle battery charging ac generator that has a switching element for turning on or off field current, the switching element is turned on at a first duty cycle less than a sum of a predetermined value and a value inversely proportional to rotation speed of the ac generator if the rotation speed is higher than a predetermined speed and at a second duty cycle more than 100% if the rotation speed is not higher than the predetermined speed.

Abstract: A method for controlling the duty cycle of a pulse width modulated (PWM) output signal applied to a field winding of an alternator of a motor vehicle. The PWM signal is generated from a controller associated with a vehicle engine to control the output current from a vehicle alternator during engine operation. The method involves determining a desired duty cycle for the PWM signal to be applied to the field winding of the alternator. The method then involves determining the PWM signal's "ON" and "OFF" pattern to deliver the desired duty cycle. This is accomplished by adding the value corresponding to the desired duty cycle to a running sum value. The PWM signal to the alternator is turned "ON" if the new running sum value exceeds or is equal to 100. One-hundred is then subtracted from the running sum value before it is stored. However, if the new running sum value is less than 100, then the PWM signal is turned "OFF" and the new running sum value is then stored without subtracting 100.

Abstract: A regulator for a brushless synchronous alternator that includes a rotary exciter having a stationary excitation inductor. The regulator includes, in combination, a power stage connected to the alternator, an analog regulator circuit connected to the power stage to regulate a plurality of parameters, a digital regulator circuit connected to the power stage to regulate a plurality of parameters, and a control circuit designed to enable the regulator unit to operate in two modes: a normal mode in which the regulation function is performed by the digital regulator circuit and a fault mode in which the regulation function is performed by the analog regulator circuit. The digital regulator circuit is isolated from the alternator, in particular mechanically and/or magnetically, and is connected to the control circuit via insulated electrical connections.

Abstract: A method of regulating voltage output from an alternator of a vehicle charging system is provided in response to transient alternator loads during idle speed operating conditions. The method comprises the steps of: (a) delivering a first alternator field control signal to the alternator; (b) detecting an impulse electrical load based on a variation in battery voltage; and (c) gradually increasing the alternator field control signal duty-cycle over a time period, such that the time period is based on the magnitude of the alternator field control signal duty-cycle, with respect to a maximum alternator field control signal duty-cycle, and based on the engine rotational speed of the vehicle, thereby regulating voltage output and torque load of the alternator.

Abstract: A brushless synchronous machine, for example a synchronous generator, having an exciter, whose field excitation winding is powered via a regulator connected to a separate auxiliary winding in the stator of the main machine in which the auxiliary winding has a number of phases that differs from the harmonic number of the harmonic wave that is the strongest in the event of a short circuit. In the case of a strong third harmonic wave, the auxiliary winding has a four- or five-phase design.

Abstract: A charge control system for an internal combustion engine which is capable of suppressing electromagnetic noise due to a control signal to a generator, and which prevents overcharging a battery even if an input terminal receiving the control signal is grounded. The charge control system is composed of a generator 1 driven by an engine of a motor vehicle and a battery 4 charged with the output of the generator 1. Also included in the system is a computer unit 2 comprising a microcomputer CPU for calculating a target voltage Vreg on the basis of the operational states of the motor vehicle for comparison with a battery voltage Vb so as to output a drive signal in accordance with the comparison result. This drive signal operates a transistor Tr, incorporated into the generator, to control a field current 1f of the generator 1 so that the quantity of the power generation of the generator 1 increases and decreases to control the quantity of the charge to the battery 4.

Abstract: A switched reluctance generator that can be used in an air cycle machine, where the generator uses the energy from the shaft of the air cycle machine to provide a back-up power supply to the magnetic bearings supporting the shaft. The generator includes circuitry for comparing the non-commutated excitation current with a command signal to regulate the excitation current, thereby regulating the generator output voltage.

Abstract: A three phase four pole alternating current generator includes an AC exciter including a series winding for each phase of the main generator windings and a shunt winding for each of the main phase windings. The series exciter windings includes two coils. In a high Y connection of the winding, the two coils are connected in series with each other and with the main phase winding. In the low voltage Y connection, series coils are separated and each is located in a paralleled leg of the same main phase winding. The shunt winding is connected directly across a corresponding main phase winding. An electronic voltage regulator includes phase voltage sensing which is coupled to a reference control circuit to produce a control signal if the voltage varies from a reference voltage. The current to the shunt winding of the exciter is controlled to maintain the desired output voltage.

Abstract: The invention relates to a turbine generator set comprising a turbine and a generator coupled to each other without a step-down gear box, and a static frequency converter connected in series between said generator and an AC electricity grid having a given operating frequency, said static frequency converter operating while the turbine generator set is generating electricity to convert the frequency of the voltage and of the current delivered by the generator into the given operating frequency of the AC electricity grid. According to the invention, while the turbine generator set is being started, said static frequency converter powers the generator which operates as a motor so as to ignite the combustion chambers of the turbine, by taking power from the AC electricity grid.

Abstract: A full-wave-rectifying-circuit is composed of six diodes and six transistors inversely connected in parallel with the diodes. A phase-control-circuit has three magnetic sensors each of which corresponds to one of the phase-windings and positioned so as to lag by an electric angle of 90.degree. to provide digital signals which lag an electric at an angle of 60.degree. behind the induced-phase-signal. The six transistors are driven by the digital signals to form controlled AC voltages which lag behind the induced line voltages by an electric angle 60.degree. so that the alternator increases the output power without increase of the body size.

Abstract: Apparatus and method for connecting a generator to an energized bus includes a circuit for determining voltage differential between the generator voltage and the bus voltage; a circuit for connecting the generator to the bus when the voltage differential reaches a predetermined threshold; a circuit for limiting the generator field current during build-up so that the generator reaches a predetermined speed before the generator is connected to the bus.

Abstract: A vehicle based AC power system includes a specialized high efficiency vehicle alternator capable of supplying its maximum rated DC output current, even when being driven by an idling vehicle engine, to power a DC to AC inverter and provide maximum rated AC power at any engine speed. The alternator is preferably a wound field and permanent magnet hybrid alternator employing a three state bridge-type voltage regulator. An electrical load monitor electrically connected to monitor the electrical load on the alternator and a transmitter and receiver are used to remotely signal a user whenever there is an excessive load on the system.

Abstract: The description concerns a voltage regulator (12) for regulating the output voltage (UB+) of an alternator (10) which is driven by an internal combustion engine. The voltage regulator (12) has an additional circuit (24) which evaluates the exciter current duty cycle (T) and supplies a signal (S1) at its output which is high when the exciter current duty cycle is high and low when the exciter current duty cycle is low. The circuit (24) is integrated in the voltage regulator (12) and the output signal (S1) supplied by it is transmitted via an additional regulator terminal (DA) and can be fed to the control device (25) of the internal combustion engine, where it is used, for instance, to increase the idling speed of the engine and accordingly also to increase the alternator speed and thus the power delivered by the alternator (10). It is also possible to switch off unnecessary consumers with this signal.

Abstract: A power generation control system for a generator is provided with a smoothing circuit, a voltage control circuit and an exciting current control circuit including a delaying circuit. When a terminal voltage of a smoothing capacitor is higher than a first reference voltage of a first comparator, a switching element is closed to supply current to an exciting coil. When a divided voltage of a voltage detecting circuit is lower than a second reference voltage of a second comparator, the smoothing capacitor is charged so that the terminal voltage thereof is gradually raised. When a detection voltage of the exciting current control circuit is higher than a third reference voltage of a third comparator, the smoothing capacitor is rapidly discharged so that the terminal voltage thereof is rapidly lowered down to a value not higher than the first reference voltage of the first comparator.

Abstract: A shorted rectififing diode protection system for a synchronous generator having a stationary exciter field which induces a voltage in a rotating exciter armature when energized by an exciter drive current, the voltage being rectified by a plurality of rotating rectifiers and applied to a rotating field winding to induce an output voltage in a plurality of main stator output phase windings, the output voltage being controlled by a voltage regulator having peak excitation current protection means, comprises a circuit for detecting actuation of the excitation current protection and generating a field protection monitor signal, a circuit for discriminating a shorted exciter field and generating a protection lock-out signal, and a logic circuit responsive to the field protection monitor signal and the protection lock-out signal for generating a shorted rectifying diode protection signal.

Abstract: An electronic voltage regulator for generators controlled by means of an exciter field current, comprises an average voltage sensing circuit connected to the output of the generator, a peak voltage sensing circuit connected to the output of the generator, an error signal circuit operatively connected to the average voltage sensing and the peak voltage sensing circuits effective to generate an error signal when the generator's average output voltage varies from a predetermined value or when the peak voltage exceeds a predetermined limit, an exciter field current control circuit operatively connected to the error signal circuit effective to control the generator field current in response to the error signal, and a shock load stabilization circuit operatively connected to the average voltage sensing circuit and to the peak voltage sensing circuit effective to disable the peak voltage sensing circuit upon sensing an application of a shock load to the generator.

Abstract: Loss of excitation and control and subsequent damage to exciter windings in an excitation system for dynamoelectric machines wherein one or more rotating diodes fail in a shorted mode is prevented through the use of an RC circuit for detecting AC voltages in an exciter field winding for the purpose of directly operating a circuit breaker to remove excitation to the field windings and supply or to activate a timer for such purposes while temporarily shorting the AC current through the exciter field winding.

Abstract: An electric power system having line drop compensation includes a controllable electric power source having an output for supplying voltage to a power bus, a local voltage regulator for monitoring the output voltage of the power source and for producing a control signal representative of a desired nominal output voltage of the power source, and a remote voltage regulator for sensing voltage on the power bus at a point of regulation located away from the power source. The remote voltage regulator produces a pulse width modulated signal having a duty cycle representative of the voltage at the point of regulation. A pulse width to trim bias converter receives the pulse width modulated signal and produces the trim signal having a magnitude representative of the duty cycle of the pulse width modulated signal.

Abstract: A stator-excited synchronous machine with an unwound, toothed rotor has a stator which is subdivided into sectors each of which is wound with an excitation winding. Permanent magnets are disposed between the stator sectors tangentially. The permanent magnets' magnetic fields in the stator sector yokes are directed in the circumferential direction, opposite to those of the adjoining excitation windings.

Abstract: A method and apparatus for controlling field current in an alternator maintains the alternator output voltage at a defined level and substantially suppresses transients in the event the alternator is disconnected from a load. A pair of MOS Insulated Gate Bipolar Transistors (MOSIGBT's) are connected one in series and one in parallel with the alternator field winding and current is provided to the field winding through the series connected regulator transistor as needed to maintain the alternator output voltage. The field current is auto-commutated through the parallel connected transient suppression transistor when the regulator transistor is off. When the alternator is disconnected from a load, both transistors are switched off in a controlled manner to discharge the field winding energy at a high voltage and at an accelerated rate within the parallel connected transistor.

Abstract: A power conversion system is operable in a generating mode to convert motive power developed by a prime mover into electrical power and in a starting mode to convert electrical power developed by a source of AC power into motive power for starting the prime mover. The system includes a stepped waveform inverter having a plurality of subinverters that are operable in the generating mode to produce rectangular waveforms wherein the waveforms are summed by a summing transformer to produce a stepped AC output waveform. During operation in the starting mode, the output of a rectifier bridge and an input of one of the subinverters are connected together by an interphase transformer. DC power is developed at a mid-tap of the interphase transformer and is delivered to the remaining subinverters which in turn develop AC power for operating a brushless generator as a motor.

Abstract: A permanent magnet generator system is provided with a permanent magnet generator having a multiple phase armature that includes several circuit branches which are electrically connected to provide a multiple phase output voltage to the output terminals of the generator. At least two of the circuit branches include an armature phase winding and a switching device electrically connected in series with the winding. The switching devices are opened and closed in response to a control signal to disconnect the generator from the remainder of the electrical system and to simultaneously de-energize the individual phase windings of the generator armature to protect against a fault occurring within the generator housing.

Abstract: A P-bar excitation system employs a generator having means for adjusting the voltage and current available from the P-bars. In some installations, the direct output of the P-bars can be connected directly to the rectifier and control circuit for development of dc excitation power. This permits elimination of the conventional excitation transformer and overall simplification of the excitation system. The voltage and current are adjusted using paired P-bars per phase, wherein each pair of P-bars is connected in series, and angularly displaced from each other about the inner circumference of the armature to attain a vector sum of voltages yielding and desired voltage per phase. In another embodiment, the generator magnetic flux, or equivalently, the number of armature turns is adjusted to yield the desired P-bar voltage and current.

Abstract: Voltage regulation of a DC electrical power source having a generator with an exciter field coil for producing an AC output voltage which is rectified to produce a DC output voltage, is accomplished by producing voltage signals proportional to the AC output voltage of the generator and the current in the generator exciter field winding, and combining these signals to produce a control signal. An additional voltage signal proportional to the DC output voltage of the power source is compared to a DC reference voltage signal to produce a trim error voltage signal. The trim error voltage signal is combined with an AC reference signal to produce an additional control signal. These control signals are compared and the result of that comparison is used to control the current in the generator exciter field winding.

Abstract: The present invention relates to a control system for an engine driven generator, and more specifically, to a control system for controlling the field current to the field coil of the generator to prevent a rapid decrease in the engine rotational speed throughout a transient period when an electric load, such as a head light or an air conditioner, is switched on and begins to draw current.In one embodiment of the invention, the control system comprises digital control means for repeatedly alternating throughout the transient period between calculating an on period and switching the field current on for the on period, and then calculating an off period and switching the field current off for the off period. The digital control means also detects a high output torque operating condition of the engine, and when such a condition is present, switches the field current on throughout the entire transient period.

Abstract: An electric braking apparatus for exerting the electric braking action (dynamic braking action) on a generator, further concretely a generator with a brushless exciter which is so constructed that a rectifying circuit for applying field voltage to the brushless exciter as a braking current to be applied to the generator is normally applied with exciting voltage at least during the running of the generator, thereby enabling the electric braking to be applied even on the generator which uses the brushless exciter and which has hitherto never been applicable of the same.

Abstract: "Doorbelling" in a generating system including a fault detecting circuit is prevented without the use of auxiliary power supply for a generator control unit. The generating system includes a permanent magnet generator (14) driving an exciter winding (18) and a relay (26) is utilized for interconnecting the two. Control of the relay (26) is exercised by a microcomputer (32) including a non-volatile memory (48) and programmed to remember the occurrence of a fault and thereafter prevent the relay (26) from cyclically opening and closing in response to power changes occurring as a result of connection and disconnection of the exciter winding (18) from the permanent magnet generator (14).

Abstract: An excitation system of a large dynamoelectric machine includes an excitation transformer having a liquid coolant system. The coolant system of the transformer is supplied with a liquid coolant, preferably from an existing source of de-ionized water, thereby permitting a smaller transformer to be used and/or the output rating of the transformer (and ultimately the output rating of the machine) to be increased, while using the same size transformer. The transformer may be disposed separate from, yet closely proximate, the machine.