Process control system

Claim 2

Apparatus for controlling a process according to means responsive to the operational state of the process producing a process variable output signal indicative thereof, comprising: a source for producing a common zero reference signal; an operational integrator connected to receive at the input thereof said reference signal, including a first capacitive feedback and a second capacitive feedback, for producing an output signal corresponding to an integral of the signals received at the input thereof; combining means adapted to receive the process variable signal and a control input signal for producing an output signal indicative of a linear combination thereof connected to said first capacitive feedback; first input generating means connected to said second capacitive feedback for producing a signal of preselected amplitude and polarity; first switching means disposed to alternatively connect said first or second capacitive feedback to the input of said operational integrator and connecting respectively the other alternative ones thereof to said reference signal; second input generating means for producing a manually variable output signal electrically independent of said operational integrator; second switching means interposed across the output of said operational integrator to alternatively connect to pass said second input generating means or said operational integrator means output signals; isolation means connected to receive said second switching means output signal for producing an output signal; and limiting means operatively connected across said first capacitive feedback for terminating the integral input to said operational integrator upon sensing a signal from said first capacitive feedback above a predetermined amplitude.

Claim 3

Apparatus according to claim 1, further comprising: said second capacitive means further including relay means disposed in series at the input side thereof and adapted to be responsive to the signal level of a power supply, for opening the input signal path when said power supply signal is below a preselected level; and said limiting including circuit elements connected between the output of said first capacitive feedback and the input of said operational integrator for referencing said output and input to said common zero reference signal.

Claim 4

Apparatus according to claim 2 wherein: said input generating means including third switching means for selectively providing signals of preselected amplitude to said second capacitive feedback.

Claim 5

Apparatus according to claim 3 wherein: said limiting means including complementary transistor means connected at the emitters thereof to said integrator output signal and adapted to receive preselected base signals to be selectively rendered conductive when said integrator output signal is above or below corresponding ones of said base signals, and switching transistor means connected to be rendered conductive by the collector signals of said complementary transistor means for conducting to connect the output of said first capacitive feedback and the input to said integrator to said zero reference signal.

Claim 6

Apparatus according to claim 4, further comprising: first meter readout means respectively connected to said combining means for producing a visual display indicative of the output signal thereof; second meter readout means operatively connected to the output of said isolating means for producing a visual display indicative thereof; and third meter readout means connected to the input of said combining means for producing a visual display corresponding to the received control signal thereat.

Claim 7

Apparatus for controlling a process, comprising: a process responsive to a process control signal and producing a process variable output signal indicative of the operation thereof; signal combining means connected to receive said process variable signal for combining said process variable signal with a manually adjustable process input signal and producing an error signal indicative of the combination thereof; first switching means connected to receive said error signal at a first terminal thereof including a contactor terminating at a second terminal and disposed to switch between the first and a third terminal; amplifying means connected to a second terminal of said switching means for amplifying the signal thereat; first capacitive feedback means connected between the output of said amplifying means and said first terminal of said first switching means for feeding back a first feedback signal indicative of a differential of said amplifying means output signal; second capacitive feedback means connected between the output of said amplifying means and the third terminal of said switching means for feeding back a second feedback signal indicative of a differential of said amplifying means output signal; first input generating means connected to said second capacitive feedback for producing a signal of preselected amplitude and polarity; second switching means connected to operate concurrent with said first switching means interposed between said amplifying means and said first and second capacitive feedback means for alternatively connecting selected other ones thereof to said amplifying means or to a zero reference signal; signal isolation means connected to receive the output signal of said second switching means for producing said process control signal indicative thereof; and limiting means operatively connected across said first capacitive feedback for terminating the integral input to said operational integrator upon sensing a signal from said first capacitive feedback above a predetermined amplitude.

Claim 8

Apparatus for controlling a process, comprising: a process responsive to a process control signal and producing a process variable output signal indicative of the operation thereof; signal combining means connected to receive said process variable signal for combining said process variable signal with a manually adjustable process input signal and producing an error signal indicative of the combination thereof; first switching means connected to receive said error signal at a first terminal thereof including a contactor terminating at a second terminal and disposed to switch between the first and a third terminal; amplifying means connected to a second terminal of said switching means for amplifying the signal thereat; first capacitive feedback means connected between the output of said amplifying means and said first terminal of said first switching means for feeding back a first feedback signal indicative of a differential of said amplifying means output signal; second capacitive feedback means connected between the output of said amplifying means and the third terminal of said switching means for feeding back a second feedback signal indicative of a differential of said amplifying means output signal; first input generating means connected to said second capacitive feedback for producing a signal of preselected amplitude and polarity; second switching means connected to operate concurrent with said first switching means interposed between said amplifying means and said first and second capacitive feedback means for alternatively connecting selected other ones thereof to said amplifying means or to a zero reference signal; signal isolation means connected to receive the output signal of said second switching means for producing said process control signal indicative thereof; and limiting means operatively connected across said first capacitive feedback for terminating the integral input to said operational integrator upon sensing a signal from said first capacitive feedback above a predetermined amplitude.

Claim 9

Apparatus according to claim 6, wherein: said first capacitive feedback means including variable resistor means for adjustment of the gain and frequency response thereof.

Claim 10

Apparatus according to claim 7, wherein: said signal combining means includes a differential amplifier connected to respectively receive said process variable signal and said process input signal for producing an output signal indicative of the difference therebetween.

Claim 11

Apparatus according to claim 8 further including: visual displays indicative of said error signal, said process input signal and said process control signal.

Claim 12

Apparatus according to claim 6 wherein: said second capacitive means further including relay means disposed at the input side thereof adapted to be responsive to the signal level of a power supply for opening the input signal path when said power supply signal is below a preselected level; and said limiting including circuit elements connected between the output of said first capacitive feedback and the input of said operational integrator for referencing said output and input to said common zero reference signal.

Claim 13

Apparatus according to claim 10, wherein: said input generating means including third switching means for selectively providing signals of preselected amplitude to said second capacitive feedback.

Claim 14

Apparatus according to claim 11, wherein: said limiting means including complementary transistor means connected at the emitters thereof to said integrator output signal and adapted to receive preselected base signals to be selectively rendered conductive when said integrator output signal is above or below corresponding ones of said base signals, and switching transistor means connected to be rendered conductive by the collector signals of said complementary transistor means for conducting to connect the output of said first capacitive feedback and the input to said integrator to said zero reference signal.