Spark interval responsive precipitator voltage control

Claim 2

A digital control for an electrostatic precipitator comprising: a detector for supplying a signal in response to the occurrence of a spark in the precipitator; a source of clock pulses; a precipitator voltage controlling digital counter connected to said source for stepwise periodic advancement by the clock pulses from said source; and circuit means connected to said detector for inhibiting the advancement of said counter by disabling the generation of one of the clock pulses by said source upon the detection of successive sparks within a predetermined time interval.

Claim 3

The control of claims 1 wherein said counter is reversible and wherein said circuit means includes means for reducing the count in said counter upon the detection of successive sparks within a second Predetermined time interval less than said first mentioned predetermined time interval.

Claim 4

The control of claim 2 wherein said circuit means includes means for additionally reducing the count in said counter upon the detection of successive sparks within a third predetermined time interval less than said second predetermined interval.

Claim 5

An automatic energization control for an electrical precipitator supplied with current by a high voltage transformer and rectifier from a source of alternating current comprising: gating means connected in the line between said source and said transformer for selectively supplying power from said source to said transformer; means for generating a signal for controlling the operation of said gating means; and circuit means substantially independent of the phase of said alternating current source and responsive to the time interval between immediately successive sparks in said precipitator for modifying the phase of said generated signal with respect to the phase of said source.

Claim 6

An automatic energization control for an electrical precipitator supplied with current by a high voltage transformer and rectifier from a source of alternating current comprising: gating means connected in the line between said source and said transformer for selectively supplying power from said source to said transformer; means for generating a signal for controlling the operation of said gating means; and circuit means substantially independent of the phase of said alternating current source and responsive to the time interval between immediately successive sparks in said precipitator for modifying the phase of said generated signal with respect to the phase of said source.

Claim 7

The control of claim 4 wherein said circuit means includes means for advancing the phase of said generated signal with respect to the phase of said source in the absence of a spark within a predetermined time interval.

Claim 8

The control of claim 5 wherein said circuit means includes means for inhibiting the advancement of the phase of said generated signal with respect to the phase of said source in response to the occurrence of a spark within a second predetermined time interval.

Claim 9

The control of claim 6 wherein said circuit means includes means for retarding the phase of said generated signal with respect to the phase of said source in response to the occurrence of a spark within a third predetermined time interval.

Claim 10

The control of claim 7 wherein said circuit means includes means for additionally retarding the phase of said generated signal with respect to the phase of said source in response to the occurrence of a spark within a fourth predetermined time interval.

Claim 11

The control of claim 8 wherein each of said predetermined time intervals are concurrently initiated and includes each of the subsequently mentioned ones of said predetermined time intervals.

Claim 12

An automatic energization control for an electrical precipitator supplied with high voltage direct current by a high voltage transformer and rectifier from a source of alternating current comprising: gating means connected in the line between said source and said transformer for selectively supplying power from said source to said transformer; means for generating a signal for controlling the operation of said gating means; and circuit means responsive to the time interval between immediately successive sparks in said precipitator for modifying the phase of said generated signal with respect to the phase of said source, said circuit means including: means for stepwise advancing the phase of said generated signal with respect to the phase of said source in the absence of a spark within a predetermined time interval, a counter connected to said signal generating means for controlling the relative phase of said generated signal, an AND gate connected to receive spark-responsive signals on one input terminal thereof, timing means for enabling said AND gate for a predetermined time interval commencing with the detection of each spark in the precipitator, means for generating periodic pulses for advancing said counter, and a bistable circuit connected to the output terminal of said AND gate for inhibiting the generation of said periodic pulses when in a set condition, said bistable circuit being placed in said set condition by the passage of a spark responsive signal through said enabled AND gate.

Claim 13

An automatic energization control for an electrical precipitator supplied with high voltage direct current by a high voltage transformer and rectifier from a source of alternating current comprising: gating means connected in the line between said source and said transformer for selectively supplying power from said source to said transformer; means for generating a signal for controlling the operation of said gating means; and circuit means responsive to the time interval between immediately successive sparks in said precipitator for modifying the phase of said generated signal with respect to the phase of said source, said circuit means including: means for stepwise advancing the phase of said generated signal with respect to the phase of said source in the absence of a spark within a predetermined time interval, a counter connected to said signal generating means for controlling the relative phase of said generated signal, an AND gate connected to receive spark-responsive signals on one input terminal thereof, timing means for enabling said AND gate for a predetermined time interval commencing with the detection of each spark in the precipitator, means for generating periodic pulses for advancing said counter, and a bistable circuit connected to the output terminal of said AND gate for inhibiting the generation of said periodic pulses when in a set condition, said bistable circuit being placed in said set condition by the passage of a spark responsive signal through said enabled AND gate.

Claim 14

An electrostatic precipitator comprising: a source of alternating current; a transformer; gating means connecting said source to said transformer; a plurality of precipitator electrodeS; a detector of sparks between said electrodes; rectifier means connecting said transformer to one of said electrodes; a digital counter connected to said gating means for controlling the current through said gating means; and circuit means connected to said detector and said counter for modifying the output of said counter in accord with the elapsed time interval between immediately successive sparks between said electrodes, said circuit means including: an AND gate connected to said detector, timing means connected to said detector for enabling said AND gate for a predetermined time interval following the detection of a spark, a source of pulses connected to said counter for periodically advancing the output thereof, and a bistable circuit for inhibiting said source, said circuit being connected to the output of said AND gate.

Claim 15

An electrostatic precipitator comprising: a source of alternating current; a transformer; gating means connecting said source to said transformer; a plurality of precipitator electrodeS; a detector of sparks between said electrodes; rectifier means connecting said transformer to one of said electrodes; a digital counter connected to said gating means for controlling the current through said gating means; and circuit means connected to said detector and said counter for modifying the output of said counter in accord with the elapsed time interval between immediately successive sparks between said electrodes, said circuit means including: an AND gate connected to said detector, timing means connected to said detector for enabling said AND gate for a predetermined time interval following the detection of a spark, a source of pulses connected to said counter for periodically advancing the output thereof, and a bistable circuit for inhibiting said source, said circuit being connected to the output of said AND gate.

Claim 16

The precipitator of claim 11 wherein said counter is reversible and includes: a second AND gate having one input connected to said bistable circuit; second circuit means connected to receive the output of said second AND gate and said source; a NOR gate connected to receive the output of said second circuit means and to supply an input to said gating means, said NOR gate being connected to the other input of said second AND gate.

Claim 17

The control of claim 10 wherein said counter is reversible and wherein said circuit means further includes: a second AND gate connected to receive a spark-responsive signal to one input terminal thereof; second timing means for enabling said second AND gate for a predetermined time interval less than said first predetermined time interval and commencing concurrently therewith; and a second bistable circuit connected to the output of said second AND gate for applying a count down pulse to said counter when in a set condition, said second bistable circuit being placed in said set condition by the passage of a spark-responsive signal through said enabled second AND gate.

Claim 18

The control of claim 13 wherein said circuit means includes: a third AND gate connected to receive spark-responsive signals on one input terminal thereof; third timing means for enabling said third AND gate for a predetermined time interval less than said second predetermined time interval and commencing concurrently therewith; and a third bistable circuit connected to the output terminal of said third AND gate for applying a plurality of count down pulses to said counter when in a set condition, said bistable circuit being placed in said set condition by the passage of a spark-responsive signal through said enabled third AND gate.

Claim 19

An electrostatic precipitator voltage control comprising: timing means for determining whether the time interval between successive precipitator sparks is less than a first predetermined value, greater than said first predetermined value but less than a second higher predetermined value, or greater than said second predetermined value; and precipitator voltage modifying means responsive to said timing means for increasing precipitator voltage responsive to a determination that the time interval between said sparks is greater than a said second predetermined value, decreasing precipitator voltage responsive to a determination that the time interval between said sparks is less than said first predetermined lower value, and maintaining precipitator voltage responsively to a determination that the time interval between said sparks is greater than said second predetermined lower value and less than said first predetermined value.

Claim 20

An electrostatic precipitator voltage control comprising: timing means for determining whether the time interval between successive precipitator sparks is less than a first predetermined value, greater than said first predetermined value but less than a second higher predetermined value, or greater than said second predetermined value; and precipitator voltage modifying means responsive to said timing means for increasing precipitator voltage responsive to a determination that the time interval between said sparks is greater than a said second predetermined value, decreasing precipitator voltage responsive to a determination that the time interval between said sparks is less than said first predetermined lower value, and maintaining precipitator voltage responsively to a determination that the time interval between said sparks is greater than said second predetermined lower value and less than said first predetermined value.

Claim 21

An electrostatic precipitator voltage control comprising: means for providing electrical signals related in occurrence to two successive precipitator sparks; timing means substantially independent of the phase of the precipitator voltage source for detecting whether the time interval between said spark-related electrical signals is less than a first predetermined value, and for generating a first output signal responsive thereto; and voltage means responsive to said first output signal for reducing precipitator voltage.

Claim 22

An electrostatic precipitator voltage control comprising: means for providing electrical signals related in occurrence to two successive precipitator sparks; timing means substantially independent of the phase of the precipitator voltage source for detecting whether the time interval between said spark-related electrical signals is less than a first predetermined value, and for generating a first output signal responsive thereto; and voltage means responsive to said first output signal for reducing precipitator voltage.

Claim 23

The control of claim 16 wherein said timing means includes: clock means, and means for detecting whether the time interval between said spark related electrical signals is less than a second predetermined value and for generating a second output signal responsively thereto; and wherein said voltage means is responsive to said clock means to raise precipitator voltage at clocked time intervals, the raising of precipitator voltage by said voltage means responsively to said clock means being inhibited for a fixed period of time responsively to said second output signal.

Claim 24

The control of claim 17 wherein said fixed period of time is substantially equal in duration to the duration of a clocked time interval.

Claim 25

The control of claim 17 wherein said clock means is reset responsively to said second output signal so that said clocked time intervals commence with the occurrence of said second output signal.

Claim 26

An electrostatic precipitator voltage control comprising: means for providing electrical signals related in occurrence to two successive precipitator sparks; timing means for detecting whether the time interval between said spark-related electrical signals is less than a first predetermined value and for generating a first output signal responsive thereto, and for detecting whether the time interval between said spark-related electrical signals is less than a second predetermined value and for generating a second output signal responsively thereto, said timing means including clock means; and voltage means responsive to said first output signal for reducing precipitator voltage, and responsive to said clock means for raising precipitator voltage at clocked time intervals, the raising of precipitator voltage by said voltage means responsively to said clock means being inhibited for a fixed period of time substantially equal in duration to the duration of a clocked time interval responsively to said second output signal.

Claim 27

An electrostatic precipitator voltage control comprising: means for providing electrical signals related in occurrence to two successive precipitator sparks; timing means for detecting whether the time interval between said spark-related electrical signals is less than a first predetermined value and for generating a first output signal responsive thereto, and for detecting whether the time interval between said spark-related electrical signals is less than a second predetermined value and for generating a second output signal responsively thereto, said timing means including clock means; and voltage means responsive to said first output signal for reducing precipitator voltage, and responsive to said clock means for raising precipitator voltage at clocked time intervals, the raising of precipitator voltage by said voltage means responsively to said clock means being inhibited for a fixed period of time substantially equal in duration to the duration of a clocked time interval responsively to said second output signal.

Claim 28

An electrostatic precipitator voltage control comprising: means for providing electrical signals related in occurrence to two successive precipitator sparks; timing means for detecting whether the time interval between said spark-related electrical signals is less than a first predetermined value and for generating a first output signal responsive thereto, and for detecting whether the time interval between said spark-related electrical signals is less than a second predetermined value and for generating a second output signal responsively thereto, said timing means including clock means; and voltage means responsive to said first output signal for reducing precipitator voltage, and responsive to said clock means for raising precipitator voltage at clocked time intervals, the raising of precipitator voltage by said voltage means responsively to said clock means being inhibited for a fixed period of time responsively to said second output signal, said clock means being reset responsively to said second output signal so that said clocked time intervals commence with the occurrence of said second output signal.

Claim 29

An electrostatic precipitator voltage control comprising: means for providing electrical signals related in occurrence to two successive precipitator sparks; timing means for detecting whether the time interval between said spark-related electrical signals is less than a first predetermined value and for generating a first output signal responsive thereto, and for detecting whether the time interval between said spark-related electrical signals is less than a second predetermined value and for generating a second output signal responsively thereto, said timing means including clock means; and voltage means responsive to said first output signal for reducing precipitator voltage, and responsive to said clock means for raising precipitator voltage at clocked time intervals, the raising of precipitator voltage by said voltage means responsively to said clock means being inhibited for a fixed period of time responsively to said second output signal, said clock means being reset responsively to said second output signal so that said clocked time intervals commence with the occurrence of said second output signal.

Claim 32

The method of claim 22 including the further step of increasing precipitator voltage when the time interval between detected sparks is greater than a second predetermined value.

Claim 33

The method of claim 23 wherein the second and third values are substantially the same.

Claim 34

The meThod of claim 23 wherein the second value is greater than the first value and wherein precipitator voltage in unchanged when the time interval between detected sparks is greater than the first value and less than the second value.

Claim 35

The method of claim 25 including the step of reducing precipitator voltage by an amount greater than the first predetermined amount when the time interval between detected sparks is less than a third predetermined value less than the first predetermined value.

Claim 36

The method of claim 22 including the further step of controlling the amount of precipitator voltage reduction in dependency on the time interval between the detected sparks.

Claim 37

An electrostatic precipitator voltage control comprising: means substantially independent of the phase of the precipitator voltage source for providing electrical signals related in occurrence to two successive precipitator sparks; timing means for detecting whether the time interval between said spark-related electrical signals is less than a first predetermined value, and for generating a first output signal responsive thereto; and voltage means responsive to said first output signal for reducing precipitator voltage.

Claim 38

An electrostatic precipitator voltage control comprising: means substantially independent of the phase of the precipitator voltage source for providing electrical signals related in occurrence to two successive precipitator sparks; timing means for detecting whether the time interval between said spark-related electrical signals is less than a first predetermined value, and for generating a first output signal responsive thereto; and voltage means responsive to said first output signal for reducing precipitator voltage.