Abstract: A method for removing precipitate from a collecting surface of an electrostatic precipitator by rapping a point on the surface. Mechanical energy is applied a plurality of times with a rapper wherein the level of mechanical energy increases from one application of energy to another. Thus preciptate is removed from regions of the collecting surface progressively more distant from the energy application point. The time period between applications is selected to cause removal of precipitate from a region of the surface to be coincident with falling precipitate from regions above. The level of mechanical energy is controlled by applying to the rapper a sequence of full half-cycles of electrical energy followed by a single phase conduction cycle. The applied current is sensed and the duration of current application is adjusted to provide a predetermined energy level to the rapper. The polarity of the current is reversed to prevent magnetization of the rapper.

Abstract: A method for removing precipitate from a collecting surface of an electrostatic precipitator by rapping a point on the surface. Mechanical energy is applied a plurality of times with a rapper wherein the level of mechanical energy increases from one application of energy to another. Thus precipitate is removed from regions of the collecting surface progressively more distant from the energy application point. The time period between applications is selected to cause removal of precipitate from a region of the surface to be coincident with falling precipitate from regions above. The level of mechanical energy is controlled by applying to the rapper a sequence of full half-cycles of electrical energy followed by a single phase conduction cycle. The applied current is sensed and the duration of current application is adjusted to provide a predetermined energy level to the rapper. The polarity of the current is reversed to prevent magnetization of the rapper.

Abstract: A control system for controlling high power from an AC source for electrostatic precipitators. The AC power is gated both on and off during the same half-cycle of the AC sources. The gating off of the AC power occurs at a time substantially different from the time of the zero crossings of the AC source. The AC source may be gated on and off respectively before and after each peak to provide high voltage to the precipator electrodes while the period of such pulsing is kept short enough to prevent arcing. Additionally, the source may be gated on after one peak and gated off before the next peak, thereby providing high voltage to the electrodes without applying the peak voltage of the AC. Further in accordance with the invention, such gating may be performed using gate turn-off thyristors. The pulses may be symmetric about the peaks or about the zero-crossings of the source. The source may also be gated on and off a plurality of times during each half cycle.

Abstract: An improved disconnect/ground switch assembly for use in conjunction with a high voltage DC power supply is disclosed. High voltage rectified DC power is provided on a conductor through an insulating bushing. An electrically conductive contacting mechanism mounted on the end of the bushing and in electrical contact with the conductor serves as a source of power for driving a pair of loads through respectively associated switching contact members. Actuating mechanisms for switching either or both of the switch contacts to associated grounded contacts are shown. Opposed apertures in the switch housing are adapted for receiving load driving conductors positioned in conductor conduits. A transparent covering of a viewing aperture for observing the positions of the switch contacts is shown.

Abstract: A high voltage DC power supply has a transformer rigidly mounted within a tank containing fluid and a support assembly, which houses various electrical components, detachably mounted therein. The support assembly, which forms a ladder-type arrangement, is held in a vertical position and at a distance away from any wall within the tank. A flexible strap containing plugs connects to mating sockets on the support assembly for electrically coupling the transformer to the electrical components housed in the support assembly.

Abstract: A high voltage DC power supply having a transformer and other electrical components housed within a tank containing fluid. A transformer is rigidly secured to the tank. There is further provided a compact, easily removable insulated support assembly for carrying at least a major portion of the other electrical components including rectifiers. The support assembly is removably secured and suspended by a support structure so that the support assembly extends within the tank independent and free of attachment to other portions of the power supply. A top of the tank is formed of a first cover and a second removably secured cover for covering an opening in the tank only substantially large enough to receive the transformer. The support assembly by itself may be quickly installed and by itself quickly removed.

Abstract: A back corona detector that reduces current flow to the plates of an electrostatic precipitator when a corona occurs between a plate and the dust layer that forms on the plate thereby minimizing the corona condition. The ramping voltage in a transformer/rectifier set under usual operating conditions will vary proportionally with current flow. At the onset of a back corona condition, a comparator senses a sudden increase in current with respect to the voltage indicating that the current is being consumed to maintain the corona rather than providing for particulate precipitation. A current set-back circuit is then pulsed periodically so that the current is continuously reduced until the voltage/current relationship is maintained at the knee of the voltage/current curve.

Abstract: A control system for automatically maintaining a maximum output voltage across the electrodes of a precipitator under varying load conditions without requiring manual readjustment of sensitivity controls. A spark threshold detector provides a threshold crossing signal when a spark occurs across the electrodes of the precipitator. Control circuitry including a ramp generator is responsive to the threshold crossing signal for providing a ramp signal which is effective to vary the voltage applied to the precipitator as a function of the desired spark rate. A sensitivity adjust circuit produces a compensating signal proportional to the magnitude of the ripple on the voltage applied to the precipitator. The DC level of the spark threshold detector is adjusted in accordance with the compensation signal so that the detector is insensitive to variations in the ripple whereby the predetermined spark rate is automatically maintained.