Abstract: A locomotive propulsion system includes wheelslip control with the following interrelated features: comparing the rotational speeds of the locomotive's separately driven wheels and detecting the highest and lowest; providing a reference speed value indicative of the rotational speed of a wheel that is not slipping; determining a desired maximum difference between the reference speed and a selected one of the detected speeds; deriving a speed error value by summing the reference speed, selected speed, and maximum difference; obtaining a wheelslip correction value which is a function of the speed error value; reducing the magnitude of voltage applied to the locomotive's traction motors in accordance with the correction value.

Abstract: A bi-stable magnetically latched electromagnetic device has an E-shaped frame, a rocker-type armature spanning the distal ends of the two outer legs of the frame, with the mid-region of the armature being pivotally supported on the distal end of the center leg for reciprocal movement between alternative stable positions, and first and second electrically interconnected helical coils each encircling a magnetizable core in a different one of the two interleg spaces of the frame. First and second permanent magnets are disposed between the base of the frame and the first and second coils, respectively, and first and second magnetic flux diverters are interposed between the respectively associated coils and magnets. The coils are connected to relatively positive and negative control power terminals via selectively operative means for providing alternative first and second current paths.

Abstract: The axial gap between the rotatable hub of a locomotive wheel and the relatively stationary thrust flange of an adjacent axle bearing is covered by a dust guard comprising an annular band of elastomeric material firmly secured to the circumference of the thrust flange and having a portion that overlaps the wheel hub. On the inside circumference of the overlapping portion of the annular band there is attached a narrow felt tape that slidingly engages the perimeter of the rotatable wheel hub to form a seal therewith, and the overlapping portion is encircled by a large-diameter hose clamp that enables a desired amount of radial pressure to be applied substantially uniformly around the felt tape.

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: To detect a d-c component of alternating current in the primary winding of an electric power transformer, a pair of current transducers are provided. Each current transducer has a saturable core adapted to be magnetized by the same current as flows in the transformer primary winding, and bias means associated with both transducers presaturate their respective cores in opposite directions by equal predetermined amounts of magnetomotive force. Secondary windings on the cores of the respective current transducers are connected to means for deriving an output signal in response to voltage induced in one but not both of the secondary windings as a result of alternating current containing a d-c component in the power transformer if such current has sufficient magnitude to unsaturate the core of one of the current transducers, a condition typifying the surge of inrush magnetizing current that flows in the transformer primary when initially energized.

Abstract: For use with an adjustable speed a-c electric motor having a stator adapted to be coupled to a source of variable frequency excitation and a rotor in which torque is developed when the motor is excited, the strength of said torque being dependent on interacting current and flux in the motor, a scheme is provided that comprises means for deriving an angle feedback signal representative of the actual phase angle between the aforesaid current and flux and means responsive to said angle feedback signal for controlling the source of variable frequency excitation so as to control the frequency of stator excitation as a function of the angle feedback signal.

Abstract: Alternating voltage for energizing an adjustable speed a-c motor is derived from unipolarity input voltage by means of electric power inverting apparatus comprising at least one pair of alternately conducting controllable electric valves. The conducting states of these valves are periodically switched by control means responsive to frequency and amplitude command signals, whereby the frequency and the amplitude of the fundamental component of the alternating voltage are varied as functions of the respective command signals. The control means includes means for implementing a triangle interception mode of pulse width modulation (PWM) of the alternating voltage so long as the amplitude command signal does not exceed a predetermined reference value (which is less than 1.

Abstract: A new induction motor control method and system utilizes one more electric power inverters each supplying a separate induction motor with alternating current excitation power. The respective inverters preferably comprise auto-sequential commutated controlled current inverters. Direct current is supplied to each inverter in the system from a common direct current power supply preferably comprising a phase controlled rectifier circuit with individual current smoothing inductors connected in the direct current link to each power inverter for isolation purposes. A common operator controlled power level control module is provided for controlling the magnitude of the output current supplied from the common phase controlled rectifier to all of the inverters in parallel. Respective motor flux sensing means are provided for each induction motor for deriving individual feedback control signals representative of the flux developed by the respective induction motors.

Abstract: A new and improved motor control method and system wherein the frequency of the rotating electro-magnetic flux produced in an alternating current machine, is sensed and compared to a desired value of machine flux frequency to derive an output error control signal. The output error control signal is then applied to control the frequency of the alternating current supplied to the machine in a direction and by an amount necessary to zero any difference in the sensed frequency and the desired frequency of machine flux. In preferred embodiments the actual value of the electromagnetic flux produced across the rotor-stator gap of the motor, is sensed and used as the controlling criterion in the motor control system. The magnitude of the alternating current supplied to the motor is separately controlled in accordance with some other predetermined motor operating characteristics such as motor torque, load current, etc.

Abstract: An electrical contact brush having interposed in a central longitudinal slot an abrasive element which frictionally contacts the commutator surface at crests where the radius of curvature of the commutator is less than that of a concave contact surface preformed at the distal end of the brush but which does not contact the commutator at valleys where the radius of curvature of the commutator is greater than that of the brush contact surface, said element in operation mechanically reducing the average radius of the commutator at a rate faster than the rate at which the commutator surface is electrically eroded, thereby tending to maintain a true cylindrical commutator surface with uniform wear characteristics.

Abstract: A multi-axled traction vehicle is equipped with a plurality of means for sensing the speeds of its respective drive axles, and control means is provided for producing a predetermined warning signal if the sensed speed of any one of the axles is under a predetermined low threshold level. In addition, means is provided for disabling the control means if none of the sensed axle speeds exceeds a predetermined higher threshold level, thereby preventing the production of a warning signal when the vehicle is not in motion.

Abstract: A torque regulating alternating current induction motor control system comprising a motor flux sensing coil arrangement mounted on the induction motor stator for sensing the actual flux produced across the rotor-stator air gap of the motor and deriving a motor flux voltage signal proportional to the actual motor flux. An integrating circuit integrates the voltage signal to obtain a feedback sensed actual motor flux signal representative of the actual air gap flux. An actual torque feedback circuit converts the actual air gap flux and stator current signal to an actual value of torque feedback control signal. A first feedback control loop is responsive to the actual torque feedback control signal and a command value of torque signal and controls the frequency of operation of a power converter supplying the induction motor.

Abstract: An electrical propulsion control system for self-propelled traction vehicles of the type having a prime mover-driven electric generator supplying energy to traction motors and regulating means for maintaining the electrical output of the generator within desired limits, wherein the limit of generator output voltage is varied between zero and a predetermined maximum level as a function of desired vehicle speed.

Abstract: An electrical propulsion control system for self-propelled traction vehicles having an electric generator supplying energy to separately excited traction motors, each motor field being normally excited with a substantially constant field excitation providing magnetic saturation such that motor load variations produce minimal changes in back emf, and means for equally boosting the excitation of each motor field responsive to the largest one of the individual motor armature currents exceeding a predetermined magnitude which is greater than the maximum attainable armature current during dynamic retarding operation.

Abstract: An improved auto-sequential commutated controlled current inverter for driving a multi-phase load from a source of controlled magnitude direct current is disclosed. The auto-sequential commutated inverter comprises a plurality of parallel connected branch sub-circuits with each branch sub-circuit comprising at least one gate controlled power thyristor device connected in series circuit relationship with a respective power diode. The branch sub-circuits thus comprised are connected between a respective phase input to the multi-phase load and a common direct current power supply terminal for connection to the source of controlled magnitude direct current. A respective commutating capacitor is interconnected between the junctures of the power thyristor and power diode of each respective branch sub-circuit and the power thyristor and power diode of the next adjacent branch sub-circuit.

Abstract: In an electric propulsion control system for self-propelled traction vehicles having reversible, variable speed tractiOn motors, wherein the operation of a direction selector means overrides the normal speed controlling means and initiates a dynamic retardation operating mode so as automatically to decrease the speed of the traction motors, and means responsive to the motors subsequently decelerating to a predetermined relatively slow speed effects a reversal of motor energization so as to reverse the direction of the vehicle.

Abstract: After vacuum pressure impregnating an insulated coil with liquid polyester resin the outer surface of the combination is treated to cause a quick low temperature gellation of an outer shell of the resin to thereby encapsulate the remaining liquid portion. A subsequent high temperature cure is imposed for a relatively long period of time to solidify the liquid inner portion and to fully cure the resin throughout the insulation.