Abstract: An apparatus for use in the simultaneous deactivation of a set of series-connected switching devices includes gate command control logic to generate a gate command signal for application to a selected switching device of the set of series-connected switching devices. A command compensation circuit processes the gate command signal. The command compensation circuit includes a time differential measurement module that forms a time differential signal indicative of the time from the previous turn-off of the selected switching device and the previous turn-off of the last switching device in the set of series-connected switching devices. A time difference processing module of the command compensation circuit process the time differential signal and creates a delay signal. A delay module of the command compensation circuit delays the gate command signal in response to the delay signal. Each switching device of the set of series-connected switching devices includes a command compensation circuit.

Abstract: The saturation of interphase transformers connected to an inverter is prevented through the use of an inverter switch firing control circuit. The inverter switch firing control circuit includes a control module to execute a standard switch firing scheme to produce a set of inverter pole output signals including a first inverter pole output signal and a second inverter pole output signal, with the first inverter pole output signal having a predetermined phase displacement from the second inverter pole output signal. The circuit also includes a control module to execute a system transient switch firing scheme wherein the inverter reduces the predetermined phase displacement between the first inverter pole output signal and the second inverter pole output signal in the presence of a system transient. This reduction in phase displacement between inverter pole output signals prevents saturation of interphase transformers. Thus, the size, cost, and weight of interphase transformers may be substantially reduced.

Abstract: An electrostatically enhanced separator (EES) which provides mechanical separation and electrostatic separation to yield a compact and highly efficient separation system. The EES (10) may be incorporated in a collection system as well using a conventional collection device such as a cyclone collector (32), bag filter (37) or electrostatic precipitator (38). The EES (10) includes a cylindrical-walled separation chamber (11) with an inlet passage (13), a clean flow outlet (21), and a particle outlet passage (15). The inlet passage (13) and particle outlet passage (15) are both thin elongated slits which open tangentially to the cylindrical wall of the chamber for providing a substantially flush incoming flow path dispersed lengthwise along the wall.

Abstract: There is provided a system and method for locating faults in power distribution systems with complex topology, such as multi-phase urban networks (6), utilizing reliable time-delay techniques as well as a transponder (22) at a monitoring point to sense the arrival of the transient fault pulse and for transmitting a timing pulse a known time delay after sensing the arrival of the transient fault pulse and a calibration pulse a known time delay after transmitting the timing pulse. Installed along the power distribution system at key locations are receiver stations (4, 4a, 4b) capable of sensing the arrival of the transient fault pulse, timing pulse and calibration pulse and measuring the time intervals occurring between each. The location of the fault is then determined based on these timing intervals, known time delays and the known propagation velocity of the electric power cables in the power distribution system.

Abstract: A magnetically annealed amorphous metal motor stator is manufactured by magnetically annealing individually the stator yoke and stator teeth and then assembling the components to form a stator so that the field is radial in the teeth and varies or is circumferential in the yoke.

Abstract: A new class of doubly-salient machines which incorporates a specific stator/rotor pole arrangement to provide a linearly increasing flux linkage over the entire area of pole overlap, and either (1) stationary permanent magnets mounted in the stator, or (2) one or more auxiliary field windings coiled about the stator or (3) a combination of stationary permanent magnets and auxiliary field windings. In each of the three cases, the permanent magnets or auxiliary winding(s) generate the primary flux and block and thereby limit flux in the ordinary path of the secondary flux (due to the stator windings) through the stator. The altered magnetic structure utilizing four stator and six rotor poles increases efficiency when operated as a generator, and provides greater output torque when operated as a motor.

Abstract: This invention provides cost-effective suppressing conducted radio-noise emissions from industrial inverter-motor drives whose EMI performance is able to meet the CISPR or FCC limits on conducted emissions. The invention includes some small size L,C filtering elements built inside the inverter, e.g., two grounding capacitance connected from both side of DC link to grounding heat sink of devices, a line capacitance across a DC link, three line capacitances across phase leads in AC input side of the diode rectifier, a zero sequence inductance both in each phase input and in each phase output lead of the inverter. Optionally, an extra secondary winding of the zero sequence inductor is connected to main circuit of inverter via a L, R, C network.

Abstract: A four pole induction machine with an extended speed range includes a stator with six independent stator coil groups (a pair of said coil groups constitutes a stator phase winding) and two current regulated inverters. Each of the inverters supplies currents to three said stator coil groups belonging to three different phases. The induction machine is operated in two operation modes: as a four pole machine, when both inverters supply currents of identical polarity, and as a two pole machine, when the polarity of currents supplied by one inverter is reversed in respect to the polarity of currents supplied by another inverter. The switching from the four pole operation mode to the two pole operation mode takes place during a constant power operation of the induction machine.

Abstract: A new class of higher phase-order (five or more) quasi square-wave back emf permanent magnet machines including radial, axial and linear embodiments which employ a greater number of active phase windings during continuous operation, thereby utilizing more of the machine copper and magnet material.

Abstract: A power switching apparatus includes a positive-sequence fundamental signal magnitude detector. The positive-sequence fundamental signal magnitude detector derives a positive-sequence fundamental signal from a three-phase voltage signal carried by a power line; it also generates a switch firing command when the positive-sequence fundamental signal exceeds a predetermined threshold value indicative of a fault condition on the power line. The power switching apparatus also includes a solid state switch connected to the power line and the positive-sequence fundamental signal magnitude detector. The solid state switch bloch power on the power line in response to the switch firing command.

Abstract: A frequency domain self-synchronization controller for solid state switches is disclosed. The controller analyzes a measured power signal in the frequency domain to identify a frequency domain firing angle and then converts the frequency domain firing angle to a time-domain firing signal command. The time-domain firing signal command is used to fire selected solid state switches of, for example, a static VAR compensator, precisely when the voltage across the selected solid state switches is at or near zero volts, so that the solid state switches are not damaged. The controller also calculates the line voltage level of the power system and in response to the voltage level it automatically executes either a high voltage coarse line conditioning strategy, a high voltage fine line conditioning strategy, a low voltage coarse line conditioning strategy, or a low voltage fine line conditioning strategy.

Abstract: A method is provided for controlling the proliferation of molluscs in target habitat by applying to the habitat a compound or mixture of compounds which are amines, ethoxylated amines, quaternary amines, ethoxylated quaternary amines and cyclic amines.

Abstract: A method is provided for improving the catalytic activity of an alcohol synthesis catalyst. In this method, the catalyst, after activation by exposure to a reducing atmosphere, is improved by contacting with a carbon dioxide-containing gas to convert the zinc oxide in the catalyst to zinc carbonate. This improvement step occurs in situ preferably in the same reactor as used for the synthesizing of the alcohol.

Abstract: An overload management system is provided, including a method and an apparatus, for controlling the operation of electrical equipment in a short-term overload region above the equipment's continuous capability operation curve, without suffering significant loss of equipment life. This overload management system is particularly beneficial for use with equipment having load management capability, such as a modular thyristor controlled series capacitor (TCSC) system using phase controlled firing based on monitored capacitor voltage and line current. For vernier operation, the system predicts an upcoming firing angle for switching a switching device to govern the current received by the electrical device, such as to bypass line current around a series capacitor of the TCSC system. The overload management system may serve as one of several higher-level controllers providing input to a vernier controller for accommodating competing objectives of various system demands.

Abstract: The present invention is directed to a type of flotation machine that combines three separate operations in a single unit. The flotation machine is a hydraulic separator that is capable of reducing the pyrite and other mineral matter content of a coal. When the hydraulic separator is used with a flotation system, the pyrite and certain other minerals particles that may have been entrained by hydrodynamic forces associated with conventional flotation machines and/or by the attachment forces associated with the formation of microagglomerates are washed and separated from the coal.

Abstract: An Uninterruptible Power Supply (UPS) for de-centralized operation in a distributed UPS system is described. The UPS system includes a number of UPS units that do not have communication links between them and therefore operate in a de-centralized manner. Coordinated operation in the UPS system is achieved through a controller associated with each UPS unit. The controller identifies when the operating power signal frequency on the UPS system does not correspond to a nominal operating frequency. In response to this condition, the controller generates a frequency reference signal that is used to control the inverter of the UPS unit. The controller continuously estimates the fractional loading of the distributed system by gauging the system response to disturbances, and sets its own operating point accordingly. The controller also ensures that the system operates at its nominal frequency independent of loading.

Abstract: An electrostatically enhanced separator (EES) provides mechanical and electrostatic separation of particles from gas stream to yield a compact and highly efficient separation system. The EES (10) may be incorporated in a collection system as well using a conventional collection device such as a cyclone collector (32), bag filter (37) or electrostatic precipitator (38). The EES (10) includes a cylindrical-walled separation chamber (12) with an inlet passage (13), a clean flow outlet (21), and a particle outlet passage (15). The inlet passage (13) and particle outlet passage (15) are both thin elongated slits which open tangentially to the cylindrical wall of the chamber for providing a substantially flush incoming flow path dispersed lengthwise along the wall.

Abstract: Methods are provided for the remediation of sites containing coal tar compositions that contain polynuclear aromatic compounds. The remediation entails altering the coal tar compositions to substantially decrease the bioavailability of the polynuclear aromatic compounds. The process includes the contacting and blending of the coal tar with petroleum coke for a time sufficient to produce a uniform admixture. The weight ratio of the petroleum coke to coal tar is generally from about 1:1 to about 10:1. Processes are also disclosed for the determination of the proper blending ratio to achieve a necessary level of remediation.

Abstract: A current source gate drive circuit for simultaneous firing of a set of series or parallel thyristors is described. The circuit includes two current loops, each of which serves as a current transformer primary. Electrically insulating tubes enclose the current loops. Current transformer cores, around which are wound a certain number of secondary turns, surround the current loops, thus magnetically coupling the primary current of the current transformer to the secondary turns. Thyristor gate driver circuits are electrically coupled to the current transformer cores. Each of the thyristor gate driver circuits receives and rectifies ac current signals from the current loops and forms a current pulse train firing signal. Each thyristor gate driver circuit has a corresponding thyristor that is fired by the current pulse train firing signal. The thyristors operate at a high voltage, but are electrically isolated from the current loops by the insulating tubes.

Abstract: A solid-state circuit breaker with fault current conduction is described. The circuit includes a power sensor connected to a power line having an up-stream side and a down-stream side. The output of the power sensor is conveyed to a switch selection circuit that identifies a line disturbance on the power line. In response to a line disturbance, the switch selection circuit generates a set of output signals. The output signals force the opening of a fault current interruption circuit including a set of turn-off thyristors. The turn-off thyristors respond to the line disturbance within a fraction of a power signal cycle to provide isolation between the up-stream side and downstream side of the power line. An alternate power source may then be applied to the down-stream side of the power line. If the line disturbance exists on the down-stream side of the power line, the output signals force the closing of a fault current conduction circuit including a set of thyristors connected in series with a reactor.