US3772853A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic voltage control apparatus for electrostatic precipitators
Assignee: Siemens Mobility Ltd
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Filing: 1971-09-09
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Granted: 1973-11-20
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Expires: 1991-09-09
Abstract
Abstract A thyristor power supply control circuit for an electrostatic precipitator which operates to tend to drive up the volts applied to the precipitator load and step it back by increments in response to sparking, the sparking being detected as a change from predominantly capacitive load circuit to a predominantly inductive load circuit and the change being instanced by current tending to flow after a.c. supply voltage zeros. Arcing within the precipitator is detected as such an inductive condition existing in two successive supply half cycles and leads to suppression of the arc by collapsing the precipitator volts for a suitable interval.
Inventors
- 👤 J Burge
- 👤 D Chilton
- 👤 D Rich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:29
CPC Classifications
B; B03; B03C; B03C3/00; B03C3/34; B03C3/66; B03C3/68; Y; Y10; Y10S; Y10S323/00; Y10S323/903
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
154 words
An automatic voltage control apparatus for an electrostatic precipitator, said apparatus comprising semiconductor controllable rectifier means for controlling the electrical power supplied to the precipitator and control means for controlling the conduction of said semiconductor controllable rectifier means so as to maintain the operation of the precipitator notwithstanding the tendency of the voltage supplied to the precipitator to be such as to cause a voltage breakdown thereacross, said control means including flashover sensing means including means for sensing the current waveform flowing to the precipitator, means for sensing the voltage waveform across the precipitator, and means responsive to said current waveform sensing means and said voltage waveform sensing means for detecting the presence in said current waveform of current flow in excess of a predetermined value subsequent to a voltage zero as sensed by said voltage waveform sensing means and for pRoducing a control signal for controlling said semiconductor controllable rectifier means responsive thereto.
Claim 2
Dependent Claim
154 words
An automatic voltage control apparatus for an electrostatic precipitator, said apparatus comprising semiconductor controllable rectifier means for controlling the electrical power supplied to the precipitator and control means for controlling the conduction of said semiconductor controllable rectifier means so as to maintain the operation of the precipitator notwithstanding the tendency of the voltage supplied to the precipitator to be such as to cause a voltage breakdown thereacross, said control means including flashover sensing means including means for sensing the current waveform flowing to the precipitator, means for sensing the voltage waveform across the precipitator, and means responsive to said current waveform sensing means and said voltage waveform sensing means for detecting the presence in said current waveform of current flow in excess of a predetermined value subsequent to a voltage zero as sensed by said voltage waveform sensing means and for pRoducing a control signal for controlling said semiconductor controllable rectifier means responsive thereto.
Claim 3
Dependent Claim
46 words
An automatic voltage control apparatus as claimed in claim 1 wherein said current waveform responsive means includes means responsive to a widening of the output current pulses produced by said semiconductor controllable rectifier means corresponding to an increase in the inductive reactive nature of the apparatus.
Claim 4
Dependent Claim
39 words
An automatic voltage control apparatus as claimed in claim 1 wherein said current waveform and voltage waveform responsive means includes means for sensing at least a predetermined reversal of the voltage waveform following a supply voltage a.c. half cycle.
Claim 5
Dependent Claim
61 words
An automatic voltage control apparatus as claimed in claim 3 wherein said current waveform and voltage waveform responsive means comprise first and second switching devices responsive to said voltage waveform, the second switching device switching to the same condition as the first switching device in response to a said predetermined reversal of the voltage waveform to produce a said control signal.
Claim 6
Dependent Claim
18 words
An automatic voltage control apparatus as claimed in claim 4 wherein said first and second switches comprise transistors.
Claim 7
Dependent Claim
42 words
An automatic voltage control apparatus as claimed in claim 4 wherein said first and second switching devices comprise first and second pairs of series connected switching transistors, one transistor of each pair being provided for each polarity of the a.c. supply waveforms.
Claim 8
Dependent Claim
53 words
An automatic voltage control apparatus as claimed in claim 1 further comprising arc control means responsive to the presence of current flow in excess of said predetermined value for a predetermined number of successive half cycles of the a.c. supply for controlling said semiconductor controllable rectifier means so as to control precipitator arcing.
Claim 9
Dependent Claim
79 words
An automatic voltage control apparatus as claimed in claim 7 wherein said arc control means includes a storage capacitor, a further capacitor, and means responsive to the said presence of current flow in excess of said predetermined value for said predetermined number of cycles for connecting said further capacitor to said storage capacitor to effect an elemental transfer of current between the capacitors and means responsive to said charge transfer for controlling conduction of said semiconductor controllable rectifier means.
Claim 10
Dependent Claim
140 words
An automatic voltage control apparatus as claimed in claim 7 wherein said arc control means includes a bistable circuit for, when switched between a first state and a second state, overriding said control signal to reduce the output of said semiconductor controllable rectifier means to a value such that precipitator arcing is extinguished within a half cycle of the supply voltage, a capacitor the charge upon which controls switching of said bistable circuit, and a capacitor charge transfer circuit for, upon detection of the presence of current flow in excess of said predetermined value subsequent to a voltage zero, transferring a predetermined charge to said capacitor, said capacitor including a charge leakage path requiring a plurality of said charge transfers within a given time interval before causing switching of said bistable circuit from said first state to said second state.
Claim 11
Dependent Claim
31 words
An automatic voltage control control apparatus as claimed in claim 7 further comprising light emitting visual indicator means for indicating the occurrence of sparks and for indicating the occurrence of arcs.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-19 | 1977-05-21 | 1977-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-19 | 1981-05-21 | 1981-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-19 | 1985-05-21 | 1985-11-20 | $7700.00 | Window Closed / Lapsed |