Abstract: An apparatus for providing a test load includes a current source in series with a resistor circuit. The current source may be a MOSFET, a shunt resistor, and operational amplifier. The resistor circuit includes a plurality of resistors and a plurality of switching semiconductors. The resistors and Insulated Gate Bipolar Transistors are arranged so that the Insulated Gate Bipolar Transistors can be switched on or off to place the resistors in series, parallel, or both with one another, thereby affecting the resistance of the resistor circuit. A microprocessor or digital signal processor outputs signals to switch the Insulated Gate Bipolar Transistors on or off.

Abstract: An ionizing bar assembly having a plastic housing with two individual ionizing electrode modules disposed on opposite sides. The ionizing electrode modules each include a plurality of printed circuit boards having signal traces thereon with ionizing electrodes or pins extending therefrom. The printed circuit boards are electrically coupled together by conductive rods or tubing positioned adjacent to the traces on the boards and soldered at various positions along the traces. The ionizing electrode modules are placed at opposing angles and are offset laterally from each other in such a way that the ionizing electrodes or pins extending from one module are located between the ionizing electrodes or pins extending from the opposite module, with the tips of each aligned along a common central linear axis.

Abstract: The total of the ion current leaving electrodes of one polarity and the ion current flowing to those electrodes, is measured as the current in the ground return path of the corresponding generator. For a brand-new ionizer, the value of that total ion current for electrodes of each polarity under normal operating conditions will substantially be the maximum ion current the positive and negative electrodes are capable of generating. The changes in the current in the ground return path reflect changes in the ionizing efficiency of the electrodes caused among other factors, by contamination. The values of the currents may be scaled up or down to the arbitrary unit. Using this scaling allows to have a signal that is normalized regardless of the length of the ionizer and number of the ionizing electrodes.

Abstract: The total of the ion current leaving electrodes of one polarity and the ion current flowing to those electrodes, is measured as the current in the ground return path of the corresponding generator. For a brand-new ionizer, the value of that total ion current for electrodes of each polarity under normal operating conditions will substantially be the maximum ion current the positive and negative electrodes are capable of generating. The changes in the current in the ground return path reflect changes in the ionizing efficiency of the electrodes caused among other factors, by contamination. The values of the currents may be scaled up or down to the arbitrary unit. Using this scaling allows to have a signal that is normalized regardless of the length of the ionizer and number of the ionizing electrodes.

Abstract: A capacitor is serially-connected to apply alternating line signal to ion generators that are normally operable on alternate half cycles of line signal for safely inhibiting further operation of a generator of air ions of one polarity in the event a generator of air ions of opposite polarity incurs circuit malfunction. In an alternative embodiment, serially-connected capacitor are shunted by serially-connected diodes poled for unidirectional conduction in opposite directions, with junctions of capacitors and diodes connected together.

Abstract: A reflector/lamp assembly employs a heat-sink component that includes a rigid, elongate, relatively wide and thin conductor element which is disposed forwardly of the reflector rim and extends radially to a distal point lying substantially beyond the axial projection of the rim. The heat-sink component efficiently dissipates thermal energy without attenuating the reflected radiation and without imposing physical constraints or stresses.

Abstract: Ionizing method and apparatus includes a pair of inverters to supply ionizing voltages to ionizing electrodes only during alternate halves of a duty cycle in which one inverter is actuated to operate at high oscillating frequency while the other inverter is inactive, and thereafter in an alternate half of the duty cycle in which the one inverter is inactive and the other inverter is actuated to operate at high oscillating frequency. Each inverter includes a return current path that combines in a common return path in which return currents may be monitored for selective control of one or both of the inverters. Small step-up transformers and other components operating at high oscillation frequency promote confined packaging of high voltage generators for convenient mounting adjacent a pair of ionizing electrodes to reduce lengths of heavily-insulated high-voltage cables between generators and electrodes.

Abstract: An active interphase reactor for twelve-pulse diode rectifiers is disclosed. The system draws near sinusoidal currents from a power utility. In one embodiment, a low kVA (0.02 P.sub.o (PU)) active current source injects a triangular current into an interphase reactor of a twelve-pulse diode rectifier. This modification results in near sinusoidal utility input currents with less than 1% THD. In alternative embodiments, a low kVA, 12-pulse system with an autotransformer arrangement (kVA rating of 0.18 P.sub.o (PU)) is implemented with the proposed active interface reactor. The resulting systems draw clean power from the utility and are suitable for powering larger kVA ac motor drive systems.

Abstract: Described is an active filter (10) for removing harmonic currents from a neutral wire (24) to reduce the current I.sub.n in the neutral wire. The filter (10) typically is located away from the source (26) and near the load (28). The filter (10) comprises generally a multi-phase transformer (12), a neutral current monitoring device (14), and a harmonic current injection device (16). The components of the present invention operate to draw a corrective harmonic current (I.sub.N) from the neutral wire (24) at a tap point (T) near the load (28) and inject the corrective harmonic current (I.sub.N) through the multi-phase transformer (12) into the phase wires (20). The corrective harmonic current (I.sub.N) substantially cancels the harmonic current (I.sub.n) in the line on the source side of the tap point (T) and therefore eliminates over-current conditions in the neutral wire. The device preferably includes a rectifier (36) connected by the secondary windings (34) of the transformer (12) to power a DC bus (38).

Abstract: A system and method for controlling a DC to AC voltage inverter. The system and method include an inverter for generating a pulse width modulated (PWM) waveform to convert a DC input voltage to an AC output voltage suitable for use with a non-linear electrical load, and a signal generator for generating a AC output voltage signal representing the AC output voltage. The system and method further include a processor for processing the AC output voltage signal to select the PWM waveform, and a control signal generator for generating a control signal based on the PWM waveform selected operative to control the inverter for generating a PWM waveform.

Abstract: An exposure system for light sensitive materials held in a vacuum frame includes an electrical light source and a power supply to the light source, the power supply having a power consumption monitor so it can modify the power supplied to the light source to compensate for any fluctuations in power consumption by the light.The light source is supported in a housing having air exhaust openings proximate the mid-portion of the light source. A blower cools the light source with a helical airflow. The voltage drop across the electrical light source is used to control the speed of the blower to maintain the voltage of the light source at a desired level. The housing has an open face and a removable pane. An indicator indicates the presence of the pane. A metal shutter in the housing has a black ceramic surface adjacent the light source to selectively expose light sensitive materials. A control means closes the shutter when the indicator senses removal of the pane while power is being supplied to the light source.

Abstract: A two terminal control switch having a main switch and a saturable current transformer whose primary winding is series connected with the main switch. A center tapped full wave rectifier has a capacitor connected between its DC sides, such capacitor also being connected to a junction between the primary winding and the main switch.

Abstract: The invention relates to a power processing technique and device wherein a tank circuit is excited at resonance, in association with two phase modulated high frequency link converters in an arrangement wherein control of the operation is easily achieved even with operation at resonance. The tank circuit is series resonant and is connected on the primary side of a transformer between two full bridge inverters and serves to control operation of the device even when operated at resonance. The technique finds special utility in power conversion applications.

Abstract: The present invention provides an electrical power inverter method and apparatus, which includes a high frequency link, for converting DC power into AC power. Generally stated, the apparatus includes a first high frequency module which produces an AC voltage at a first output frequency, and a second high frequency inverter module which produces an AC voltage at a second output frequency that is substantially the same as the first output frequency. The second AC voltage is out of phase with the first AC voltage by a selected angular phase displacement. A mixer mixes the first and second output voltages to produce a high frequency carrier which has a selected base frequency impressed on the sidebands thereof. A rectifier rectifies the carrier, and a filter filters the rectified carrier. An output inverter inverts the filtered carrier to produce an AC line voltage at the selected base frequency.

Abstract: A lag ballast for a high intensity discharge lamp includes a transformer providing voltage at either of two levels. Triacs tied to the transformer supply current at the desired voltage level through either of two inductances. The triacs are controlled by a comparison circuit so that a low voltage and high current are supplied to the lamp during startup and a lower current and higher voltage are supplied as the lamp approaches its normal operating temperature.

Abstract: A mounting arrangement for a photocell is disclosed which allows detection of ambient lighting. A collar is secured to a mounting surface by an integral flange and a locking collar. The photocell is fixed within a body member slidingly positioned within the collar. An adjustable aperture in the body member allows ambient light to be detected.

Abstract: The invention is directed to a circuit and a method for efficiently controlling the output illumination level in gas discharge lighting arrangements. Load side control is provided by a timed interval controlled impedance, serially coupled between the ballast and the lamp(s). A circulating inductor, coupled in parallel with the controlled impedance, provides a current path between the power source and the lamp(s) at least during that portion of the AC waveform where the controlled impedance is in a substantially non-conducting state.

Abstract: The invention is directed to a circuit and a method for efficiently controlling the output illumination level of a gas discharge lighting arrangement having four or more gas discharge lamps with multiple ballasts. Load side control of each ballast is provided by a timed interval controlled impedance, serially coupled between the particular ballast and its associated lamps. A circulating inductor, coupled in parallel with each controlled impedance, provides a current path between the power source and the lamps at least during that portion of the AC waveform when the controlled impedances are non-conducting. The invention is equally operable at both 120 volt and 277 volt AC levels without major component changes.

Abstract: The invention is directed to a circuit and a method for efficiently controlling the output illumination level in gas discharge lighting arrangements. Load side control is provided by a timed interval controlled impedance, serially coupled between the ballast and the lamp(s). A circulating inductor, coupled in parallel with the controlled impedance, provides a current path between the power source and the lamp(s) at least during that portion of the AC waveform where the controlled impedance is in a substantially non-conducting state.

Abstract: The invention is directed to a circuit and a method for efficiently controlling the output illumination level of a gas discharge lighting arrangement having four or more gas discharge lamps with multiple ballasts. Load side control of each ballast is provided by a timed interval controlled impedance, serially coupled between the particular ballast and its associated lamps. A circulating inductor, coupled in parallel with each controlled impedance, provides a current path between the power source and the lamps at least during that portion of the AC waveform when the controlled impedances are non-conducting. The invention is equally operable at both 120 volt and 277 volt AC levels without major component changes.