US3829845A
Expired / Lapsed
US
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Process control method and apparatus
Assignee: Reliance Electric Co
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Filing: 1973-08-24
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Granted: 1974-08-13
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Expires: 1993-08-24
Abstract
Abstract Noise immunity is enhanced in a digital computer controlled process by phase-shifting input signals before they are sampled by the computer to remove high frequency noise using small filters having short time constants, by sensing the phase-shifted signals when they are near their peak amplitudes, which is arranged to occur when line voltage is not at its peak amplitude, then processing the sensed signals and transmitting command signals either the first or a subsequent time after such sensing that the line voltage passes through zero.
Inventors
- 👤 D Means
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 12:50
CPC Classifications
G; G05; G05B; G05B9/00; G05B9/02; G05B19/00; G05B19/02; G05B19/04; H; H04; H04B; H04B1/00; H04B1/06; H04B1/10; H04B1/1018; G05B2219/00; G05B2219/20; G05B2219/21; G05B2219/21136
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
104 words
The method of controlling a process control system which is powered by an alternating voltage source comprising the steps of continuously filtering a first group of signals representing process control parameters to remove high frequency noise components from said signals and to provide a second group of filtered signals each shifted in phase by a predetermined amount from said voltage source; sensing said second group of signals at a time which is later than the time at which said alternating voltage source is at its maximum amplitude; processing said sensed signals to provide process control command signals; and executing said process control command signals.
Claim 2
Independent Claim
104 words
The method of controlling a process control system which is powered by an alternating voltage source comprising the steps of continuously filtering a first group of signals representing process control parameters to remove high frequency noise components from said signals and to provide a second group of filtered signals each shifted in phase by a predetermined amount from said voltage source; sensing said second group of signals at a time which is later than the time at which said alternating voltage source is at its maximum amplitude; processing said sensed signals to provide process control command signals; and executing said process control command signals.
Claim 3
Dependent Claim
24 words
The method according to claim 1 wherein said step of filtering said first group of signals comprises low-pass filtering said first group of signals.
Claim 4
Dependent Claim
48 words
The method according to claim 1 wherein said step of filtering comprises shifting the phase of said first group of signals so that said signals of said second group lag said signals of said first group more than five degrees of a cycle of said alternating voltage source.
Claim 5
Dependent Claim
47 words
The method according to claim 1 wherein said alternating voltage source has a frequency of substantially 60 hertz and said step of filtering is operative to provide said signals of said second group each with a phase lagging at least ten degrees behind said alternating voltage source.
Claim 6
Dependent Claim
30 words
The method according to claim 1 wherein said step of sensing comprises sampling said signals of said second group at a time when they are substantially at their maximum amplitudes.
Claim 7
Dependent Claim
29 words
The method according to claim 1 wherein said step of sensing comprises sampling said signals of said second group during alternate half-cycles of said signals of said second group.
Claim 8
Dependent Claim
35 words
The method according to claim 1 wherein said step of executing said process control command signals comprises transmitting said command signals at a time when said alternating voltage source is substantially at its minimum amplitude.
Claim 9
Dependent Claim
74 words
The method according to claim 7 wherein said step of processing said sensed signals comprises processing said sensed signals until after the first time at which said voltage source passes through its minimum amplitude after said step of sensing, and wherein sAid step of executing comprises transmitting said command signals at substantially the second time or a later time at which said voltage source passes through its minimum amplitude after said step of sensing.
Claim 10
Dependent Claim
58 words
The method according to claim 7 wherein said step of executing comprises transmitting said command signals at substantially the first time at which said voltage source passes through its minimum amplitude after said step of sensing, and wherein said step of processing comprises processing said sensed signals in between said step of sensing and said step of transmitting.
Claim 11
Dependent Claim
147 words
A process control system, comprising, in combination: data-processing apparatus for receiving sensed signals, processing said sensed signals, and providing process control command signals, said apparatus including sampling means for periodically sensing input signals; a plurality of process control parameter sensing means for providing a first group of signals each representative of a process condition; an alternating voltage source connected to power said sensing means and connected to said data-processing apparatus; and a plurality of filter means connected to respective ones of said sensing means to remove high frequency noise components from said signals of said first group and to provide a second group of filtered signals shifted in phase relative to said voltage source, said sampling means being arranged to sense said signals of said second group at a time which is substantially later than the time at which said voltage source is at its maximum amplitude.
Claim 12
Dependent Claim
147 words
A process control system, comprising, in combination: data-processing apparatus for receiving sensed signals, processing said sensed signals, and providing process control command signals, said apparatus including sampling means for periodically sensing input signals; a plurality of process control parameter sensing means for providing a first group of signals each representative of a process condition; an alternating voltage source connected to power said sensing means and connected to said data-processing apparatus; and a plurality of filter means connected to respective ones of said sensing means to remove high frequency noise components from said signals of said first group and to provide a second group of filtered signals shifted in phase relative to said voltage source, said sampling means being arranged to sense said signals of said second group at a time which is substantially later than the time at which said voltage source is at its maximum amplitude.
Claim 13
Dependent Claim
16 words
A system according to claim 10 wherein each of said filter means comprises a low-pass filter.
Claim 14
Dependent Claim
22 words
A system according to claim 10 wherein at least one of said filter means comprises a series resistance and a shunt capacitance.
Claim 15
Dependent Claim
28 words
A system according to claim 10 wherein said sampling means is arranged to sample said signals of said second group substantially at the time of their peak values.
Claim 16
Dependent Claim
30 words
A system according to claim 10 having resistance means associated with at least one of said filters for attenuating the input signal received by said one filter at all frequencies.
References Cited (Backward Citations)
US3651477A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-12 | 1978-02-11 | 1978-08-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-12 | 1982-02-11 | 1982-08-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-12 | 1986-02-11 | 1986-08-13 | $7700.00 | Window Closed / Lapsed |