Abstract: An improved electrical circuit configuration for a chopper circuit is disclosed which is particularly adapted for use with an inductive load such as a braking resistor of the type used in many rapid transit vehicles. Instead of connecting a di/dt reactor directly in series with the electronic switch of the chopper circuit, a di/dt reactor is connected in series with the freewheeling diode. Using this configuration, the di/dt reactor does not have to continuously handle the average current through the electronic switch during the entire chopping operation. Hence, a much smaller, lighter, and less expensive di/dt reactor can be utilized.

Abstract: A power supply has a stack formed by a first bus plate, a gate take off (GTO) thyristor, a second bus plate, a bypass diode and a third bus plate all mounted to a heat sink by a single clamp, with the anode of the thyristor closest to the heat sink. Preferably, the bus plates are sized and of a material to provide local thermal storage. The heat sink then can be sized to handle only the average heat dissipation requirements, rather than the peak requirements, and the total power supply can be very compact.

Abstract: A compartmentalized tank divided into a plurality of compartments are fluidly connected to a filling chamber wherein the filling chamber has an overflow fluid passage to each of the plurality of compartments and a fluid channel elevationally below the overflow fluid passage which conducts fluid flow during filling of the compartments but does not conduct fluid flow between the compartments when the tank is improperly oriented. Each of the plurality of compartments may include an orientation restrictive air vent, such as one formed by an elongated air channel positioned to reduce the loss of fluid in the event the tank is tipped on its side. The fluid channel has a plurality of orifices for conducting fluid flow from the filling chamber to the plurality of compartments which prevent fluid loss when a compartment is damaged.In another embodiment, the tank includes a supply line and a return line in each compartment.

Abstract: Flashover protection is provided for a locomotive propulsion system including a plurality of d-c traction motors each having a commutator subject to flashovers, a traction alternator having armature and field windings and a rotor driven by a prime mover, a controllable source of excitation current connected to the alternator field, and means including an electric power rectifier for connecting the alternator to the motor commutators. It comprises means for producing a fault signal whenever a flashover occurs in any motor, a solid-state controllable electric valve connected between the excitation current source and the alternator field and having alternative conducting and non-conducting states, and means for changing the valve from conducting to non-conducting states in response to a fault signal being produced, whereupon the magnitude of excitation current in the alternator field is rapidly reduced toward zero and the alternator's output current is correspondingly decreased whenever a flashover occurs.

Abstract: A method and apparatus for controlling an inverter circuit to convert dc voltage to variable amplitude and frequency ac voltage use firing pattern tables which are stored and selected in accordance with a required voltage level for the ac voltage. The firing pattern tables are accessed by writable timers which both address the firing pattern tables and define the times between readout of consecutive entires of the firing pattern tables. If requirements of the ac voltage being produced are changed, a new firing pattern table is selected at the end of the currently selected pattern table. Further, as the required frequency of the ac voltage being produced changes during the readout of a selected firing pattern table, the times written into the writable timers are changed accordingly to vary the frequency of the ac signal on the fly. Angle tables corresponding to the pattern tables are stored and accessed by a control processor to determine the times written into the timers.

Abstract: A mounting arrangement for a pair of relatively high voltage, press-pack semiconductors positioned in spaced apart relationship on a support surface of a heat sink comprises an enclosure formed of electrically insulative material having a mounting surface mating with the heat sink support surface. The arrangement has a pair of spaced openings extending through the mounting surface, each of which is configured for relatively accurately positioning a respective one of the semiconductors. A groove circumscribes each opening with a third groove spaced from and circumscribing the pair of grooves on the mounting surface. An O-ring in each groove defines an area between the grooves isolated from environmental contaminants when the enclosure is clamped to the heat sink. An electrically conductive mounting plate is positioned in each opening and electrically insulated from the heat sink but electrically connected to a respective semiconductor.

Abstract: A motor support bearing assembly is provided for a live axle used in locomotives. A wheel is press fit on each end of the axle under high pressure, with a gear secured between the wheels adjacent the pinion end of the axle. The motor support bearing assembly is located between the plain end wheel at the commutator end and the axle gear at the other end, and includes a housing, a tapered roller bearing adjacent the plain end wheel, and another tapered roller bearing adjacent the axle gear. In the motor support bearing assembly process, a master spacer made of hardened metal is placed in a selected space in the assembly. The plain end wheel is pressed onto the axle under high pressure. Axial end play in the motor support bearings is set by applying a spike of additional pressure to the plain end wheel, pressing the bearings together tightly and in some cases pre-loading the bearings.

Abstract: The trailing edge of a carbon brush for commutating electric machines has a notch flanked by an ear on either side. The brush can include one or more wafers. The angular thickness of the trailing brush wafer at the notch is such that the brush does not touch more than n commutator contacts at a time. However, the brush wafer is thick enough at the ears to touch n+1commutator contacts at a time. The relatively high resistance of the ears improves commutation.

Abstract: An electrical propulsion system for a traction vehicle adapted to haul a payload, the vehicle being equipped with weight sensing device for distinguishing between loaded and unloaded conditions and with communication device adapted to receive from an external source a coded signal indicative of a given speed limit, the system including electric motors driving a pair of vehicle wheels, a controllable source of electric power for the motors, a device for switching from propulsion to electrical retarding modes of operation in response to the actual speed of the vehicle becoming greater than a desired maximum, and a device connected to the weight sensing device and to the communication device for automatically adjusting the maximum propulsion speed so that it is lower when said loaded condition is true than when said unloaded condition is true and for automatically changing the maximum propulsion speed as necessary to avoid exceeding the limit indicated by the coded signal.

Abstract: For use in a welded resistor grid assembly moving a plurality of generally parallel, relatively think plate-like metal elements disposed between a pair of spaced-apart insulating support members having a plurality of slotted openings in their opposing sidewalls, a metal element having a substantially rectangular plate-like body of predetermined width, a coplanar flat segment of the same width at one end of the body, a laterally offset flat segment of the same width at the opposite end of the body, the upraised side of the later segment having a flat surface adapted to be joined by a seam weld to the flat surface of the other side of the coplanar segment of another duplicate element after two such elements are placed side by side with opposite orientation so that the offset flat segment of one adjoins the coplanar flat segment of the other, and a border segment of the same width contiguous and generally coplanar with a first one of the flat segments, the border segment being adapted to enter a slotted opening

Abstract: In an electric power converter comprising at least one pair of serially-connected, alternately conducting controllable electric valves spanning a pair of d-c conductors, the conducting state of each valve is detected by comparing the actual magnitude of valve current with a predetermined low threshold level and by comparing the difference between the juncture potential of the two valves and a reference potential of one of the d-c conductors with the potential diffence between both d-c conductors. If both comparisons indicate the valve is in a conducting state and if this state is indicted concurrently for both valves, logic means is operative to indicate that a "shoot through" fault has occurred. In this abnormal event, whatever turn on and turn off signals for the two valves were extant at the time such operation of the logic means commenced will be prevented from changing while both valves are conducting.

Abstract: A condition responsive switching apparatus with an alarm feature for use in refrigeration appliances, such as freezers or the like. The switching apparatus includes a contact operator which moves between first, second, and third positions in response to the pressure changes of a bellows. The bellows pressure increases and decreases in response to changes in temperature sensed at the appliance. The apparatus includes a first set of control contacts to provide energization of a compressor and a second set of alarm contacts to provide energization of an alarm circuit. The contact operator has a first dog which opens and closes the control set of contacts as the operator moves through a snap action increment of travel between the first and second positions. An alarm spring opposes the travel of a second dog of the contact operator beyond the second position with a preload force until the excess of the snap action energy of the operator is dissipated.

Abstract: Magnet wire substrates (1) are described having a layer of polyester tape (2) wrapped thereon, including a layer of spirally wrapped and bonded polyester insulation tape (3) as the outermost layer. The two tape layers are made up of amorphous (4) and crystalline (5) segments unbonded to the wire and bonded to each other to provide the requisite electrical properties and improved physical properties including increased flexibility and ease of strippability. A single multilayer polyester insulation tape can also be used with similar properties and reduced thickness.

Abstract: The invention discloses a high solids wire enamel having a surprisingly low viscosity. The enamel comprises a mixture of high molecular weight and low molecular weight linear hydroxy polyethers, a phenolic resin, an isocyanate and possibly a melamine. The resulting enamel has excellent flexibility and resistance to crazing.

Abstract: A heat deformable tube having a melt liner of noncross-linked, thermoplastic material, such that upon heating to a temperature high enough to cause the tube to return to its original shape; the melt liner melts and encapsulates the substrate.

Abstract: A cable shielding system is disclosed wherein corrugated metal shielding has its edges bent to a predetermined configuration prior to being formed about the cable. Upon being formed around the cable, the sheathing with the pre-bent edges forms a closed passage way within the seam for receiving an adhesive. The pre-bent edge configuration reduces the possibility that the edge of the metallic sheathing will damage an externally applied plastic sheath.