Abstract: The magnitudes of currents in the armature and field windings of a separately excited d-c motor are compared, and a fault signal is produced in response to the field current magnitude either rising above a first reference level (which varies as a first predetermined function of the armature current magnitude) or falling below a second reference level (which varies as another predetermined function of the latter magnitude).

Abstract: A variable speed 3-phase a-c motor is connected via a plurality of controllable bidirectional switches to a 3-phase source of alternating voltage having a variable fundamental frequency (f) and an rms magnitude (v) that varies with f, and the switches are suitably arranged and controlled so that motor speed can be reduced by skipping selected cycles of the source voltage. When operating at a fraction of full speed, the magnitude-to-frequency ratio of motor voltage is maintained substantially the same as at full speed by varying the "firing angle" at which the switches start conducting current so as to minimize any deviation of the rms magnitude of the motor voltage from the product of v times said fraction.

Abstract: Two separately-excited d-c electric motors are used to drive the wheels of a traction vehicle. The magnitude of motor field current varies as a function of the value of a variable control signal, which value is representative of any deviation of the field current magnitude from a given reference magnitude. When electric braking of the vehicle is desired, the reference magnitude is normally determined by the difference (if any) between the actual rotational speed of the slower motor and a predetermined desired speed, whereby motor field current is varied as necessary to regulate the retard speed of the vehicle. Means is provided for automatically initiating the retard speed regulation mode of operation as the vehicle accelerates and the actual rotational speed of the faster motor approaches the aforesaid desired speed.

Abstract: A hybrid phase-controlled rectifying bridge includes both controlled and uncontrolled electric valves referred to as thyristors and diodes, respectively. Each of a pair of thyristors is periodically fired at an "angle" that can be advanced or retarded as desired, whereupon load current commutates to the thyristor from the corresponding diode. Subsequently the thyristor is turned off at a desired extinction angle by the action of cyclically operative forced commutation means. To avoid reverse recovery overvoltages across a diode when the desired extinction angle is only slightly larger than the firing angle, means is provided for temporarily preventing any turnoff action during the diode-to-thyristor commutation interval and for an additional interval that gives the diode sufficient time to fully recover its reverse blocking capability.

Abstract: A phase-controlled ac-to-dc rectifying circuit includes a pair of alternately conducting main controllable electric valves and cyclically operative forced commutation means for turning off the main valves. The forced commutation means comprises a pair of auxiliary controlled rectifiers respectively connected, in circuit with a commutating capacitor, across the main valves, and the auxiliary rectifiers are alternately turned on in response to periodic trigger signals that are normally produced by associated control means. Protective means is provided for inhibiting the trigger signals when the magnitude of voltage across the commutating capacitor is lower than a critical level which depends on the magnitude of the current being conducted by the main valves, thereby avoiding a risk of commutation failure due to low capacitor voltage.

Abstract: Apparatus for controlling wheel slip in a locomotive driven by d.c. motors which receive power from a diesel driven generator, has sensors which provide signals representing speeds of different driven wheels to a velocity unit. The velocity unit derives a differential signal representing the difference between the highest and the lowest wheel speeds. A sensor detects current or power in the generator output and the signal from this sensor is sampled periodically and the latest two sampled values are stored. The sampled values are compared to provide a creep reference signal. The differential signal and the creep reference signal are compared and the resulting difference signal is used to control generator output to maximize current during acceleration.

Abstract: A variable speed 3-phase a-c motor is connected to a 3-phase source of alternating voltage via five controllable bidirectional solid state switches which are so arranged and controlled that motor speed can be reduced by skipping selected cycles of the source voltage. For example, for half speed operation three of the switches are arranged respectively to connect phases A, B and C of the source to phases A, C and B of the motor, and over two consecutive periods of the source voltage three separate, uniformly spaced "firing windows" are selected during which the conducting states of these switches are initiated in a predetermined pattern that results in the phase A-to-phase B source voltage being applied to the motor during the first window, the phase C-to-phase A source voltage being applied during the next window, and the phase B-to-phase C source voltage being applied during the last window.

Abstract: In the propulsion system of an electric locomotive, a-c wayside power is converted to direct current for the traction motors by means of several phase-controlled rectifying bridges having serially connected outputs. The bridges are controlled sequentially so that their respective output voltages are introduced in stages as increasing amounts of voltage are required at the motors of an accelerating locomotive. Normally certain thresholds of speed need to be attained before the second bridge, and later the third bridge, are permitted to be phased on. Means is provided for changing the bridge control sequence in response to faults in the first or second bridges.

Abstract: The rotatable impeller of a single-stage centrifugal blower is housed in a casing one side of which comprises a spiral plenum having an opening which extends along a predetermined limited portion of the perimeter of the impeller and the other side of which includes a port located near the periphery of the impeller but displaced from the opening of the plenum so that it is out of register with that opening. The spiral plenum includes an exit section that provides a first fluid outlet from the casing, and the port serves as a second, independent fluid outlet.

Abstract: In the propulsion system of an electric locomotive, a-c wayside power is converted to direct current for the traction motors by a plurality of phase-controlled rectifying circuits having serially connected outputs. To improve power factor, forced commutation means is provided for turning off the controllable valves in one of the circuits at a desired "extinction angle." This angle is varied with motor speed, but its effective range of variation is restricted so as to avoid undesired leading power factor at low speeds, to optimize power factor when the locomotive is running at full power, and to prevent misoperation when the level of load current is low.

Abstract: A circuit having means responsive to a plurality of electric signals representative, respectively, of the speeds of a plurality of traction motors in a propulsion system for a traction vehicle, wherein the circuit provides a digital output signal having a frequency representative of the average speed of the respective motors.

Abstract: A method of insulating an electromagnetic coil comprises the steps of wrapping first and second overlapping layers of fluorinated ethylene propylene (FEP) resin-coated polyimide tape around distal sections of the end turns of the coil, inserting conforming laminae of FEP resin-impregnated glass cloth between adjacent coil turns, wrapping at least two overlapping layers of FEP resin-coated polyimide tape around the entire coil, heating the coil to at least the resin melting point, applying pressure to compress the tape and laminae and to clamp together the respective turns of the coil, and finally cooling the coil under pressure to allow the resin to resolidify. The resulting product has a thin, uniform coating of impervious electrical insulation characterized by improved heat transfer capability and improved stability at high temperatures.

Abstract: The magnet frame of a dynamoelectric machine comprises a removable, generally cylindrical inner member concentrically disposed inside a cylindrical outer member. The inner member is supported in a cantilever fashion at only one of its ends, and most of its outside surface is normally separated by a relatively small circumferential gap from the cooperating inside surface of the outer member. The outer member of the frame rotatably supports the hub of a motorized wheel, which hub is coupled via a torque tube and gearing to a rotor inside the inner member. Conventional means is provided in the inner member for producing a field of magnetic flux in both the magnet frame and the rotor, and the path of this flux will include parallel branches in the inner and outer frame members.

Abstract: An internal combustion engine overspeed protection system utilizes a spring-actuated expandable overspeed link in the fuel control linkage to shut off fuel independently of governor or throttle action. The link is normally latched in a contracted condition and positioned in the fuel linkage between a manual fuel lever and the fuel cranks for the respective cylinders of the engine. An automatically resetable hydraulic actuating device unlatches the link in high speed response to an engine overspeed condition. A spring coupling in the fuel linkage permits relatching of the overspeed link by manipulation of the fuel lever.

Abstract: A non-micaceous commutator cone for insulating commutator bars from retaining rings of a commutator assembly in a dynamoelectric machine, comprising an annular laminated member including at least one layer of non-conductive, resin-impregnated fibrous elements sandwiched between outer layers of thin, seamless, impervious, non-thermoplastic polymeric films. The wall of this laminate has the dielectric strength, the uniform thickness, the stability, and the resiliency that are required for a commutator cone in a relatively large, high temperature machine.

Abstract: An electromagnet coil comprises a plurality of turns, including a pair of end turns having distal sections wrapped in first and second overlapping layers of fluorinated ethylene propylene (FEP) resin-coated polyimide tape. Conforming laminae of FEP resin-impregnated glass cloth are inserted between and bonded to adjacent turns of the coil. The entire coil is wrapped in at least two overlapping layers of the aforesaid tape, with the inner layer being bonded to the surface of the coil turns that it covers and the respectively adjoining layers of tape being bonded to each other. The resulting product has a thin, uniform coating of impervious electrical insulation characterized by improved heat transfer capability and improved stability at high temperatures.

Abstract: A movable member, including a first piston in a hydraulic cylinder, is biased toward a first position by a reset spring and toward a second position by a trip spring which is compressed between the first piston and a second piston in the same cylinder. The second piston is disposed for limited floating movement relative to said movable member. Hydraulic fluid under pressure is admitted into a first chamber between the first piston and the adjacent end of the cylinder, and a constricted fluid passage in the movable member enables the hydraulic fluid to flow between the first chamber and a second chamber defined by the second, floating piston and the other end of the cylinder. With equal, relatively high fluid pressure in both chambers, the trip spring is charged and the movable member is held by the reset spring in its first position.

Abstract: A traction vehicle propulsion system comprises a d-c motor and an excitation generator for separately exciting the motor field. Current in the field winding of the excitation generator is normally controlled by a control circuit which is arranged to prevent vehicle misdirection due to control circuit failure modes wherein normal excitation current is not supplied. The control circuit comprises means responsive to an acceleration command signal for temporarily removing the field winding from the normal control circuit and for placing it instead in a biasing circuit comprising low impedance paths to the respective terminals of a direct voltage source, thereby presetting the magnetic field of the field winding in the proper direction to prevent vehicle misdirection upon acceleration from rest.

Abstract: A multi-winding a-c electric power supply is connected to a d-c load circuit via a power rectifier assembly comprising at least two legs connected in parallel across the load circuit. Each leg has at least four serially interconnected unilaterally conducting devices. A first one of the power supply windings is connected between the two rectifier legs at points between first and second devices thereof, and a duplicate winding (voltages of both windings are in-phase and of equal amplitude) is connected between the legs at points between third and fourth devices thereof, whereby the windings are effectively connected in parallel. The respective junctures of the second and third devices in all of the rectifier legs are interconnected by switching means which, upon switching to a closed circuit state, short circuits these junctures and thereby changes the connection of the windings from parallel to series.

Abstract: An engine-driven dual winding separately excited alternator supplies electric power to a parallel array of d-c traction motors via a power rectifier assembly comprising three legs of serially interconnected diodes. The alternator has a first set of 3-phase windings respectively connected to the three rectifier legs at points between first and second diodes thereof and another set of duplicate windings respectively connected to the corresponding legs at points between third and fourth diodes thereof. First and second switching means are used to interconnect the respective junctures of the second and third diodes of all three rectifier legs, and in response to transition command signals these switching means are selectively closed (or opened) in sequence to change the connection of the alternator windings from parallel to series (or vice versa). Stabilizing means associated with the excitation system of the alternator is temporarily disabled during the transition interval.