Abstract: An electromagnetic flowmeter for measuring the flow rate of a ferromagnetic slurry which is conducted through a flow tube having electrodes mounted thereon, the slurry intercepting a magnetic field to induce a signal in the electrodes which depends on flow rate. The field is established by an electromagnetic circuit whose core has a gap defined by the tube, an excitation coil being wound about the core. The magnetic resistance of the circuit changes as a function of the ferromagnetic concentration of the slurry, this change affecting the inductance of the coil. To provide an output signal which accurately reflects flow rate regardless of ferromagnetic concentration, the output signal is corrected in accordance with the changing inductance of the excitation coil.

Abstract: An apparatus is disclosed for converting a physical quantity into variations in electric current. The apparatus comprises a power source, a control circuit for controlling an output amplitude of the power source, a detecting circuit supplied with the output of the power source, the electrical characteristics of the detecting circuit being varied in accordance with a physical quantity to be measured and ambient conditions, a converting circuit for amplifying the difference between a first electrical output of the detecting circuit and a reference value, and for converting the amplified difference into an output of the apparatus, and a negative feedback circuit for feeding back a portion of the output to the control circuit. A second electrical output of the detecting circuit is also input to the control circuit whereby the output of the control circuit controls the output amplitude of the power source.

Abstract: A capacitance type displacement conversion device is provided in which a physical displacement resulted from a change of a physical value such as pressure or tension is converted into an electrical signal. The device is comprised of a capacitance sensor and an improved circuitry whereby conversion characteristics are linear and free from erroneous measurements caused by distributed capacitances and other circuit elements related thereto. The type of the sensor may be either a single capacitance or a differential capacitance type.

Abstract: A pressure transducer which produces an output capacitance signal which is unaffected by temperature or mechanical distortion. A sensing chamber is provided at the center of a pressure sensor body with the sensing chamber being filled with a sealed liquid. A moving electrode of a cantilever structure is disposed in the sensing chamber and a through hole extends from the sensing chamber to at least one side of the pressure sensor body. A pressure receiving element is disposed on at least one side of the pressure sensor body and a rod couples the pressure receiving element and the moving electrode through the through hole. Two fixed electrodes of a cantilever structure are disposed opposite the moving electrode to form first and second variable capacitance elements together with the moving electrode.

Abstract: An electromagnetic flowmeter in which the fluid whose flow rate is to be measured is conducted through the flow tube of a primary provided with a pair of diametrically-opposed electrodes to intercept a magnetic field established by an electromagnet whose coil is excited by a current having a rectangular waveform whose frequency is low relative to that of a commercial a-c power line. The electrodes of the primary are connected through a transmission line to the input amplifiers of a secondary, the transmission line being constituted by a pair of shielded cables each including an inner line connecting an electrode to the input of a respective amplifier and an outer shield connected to the output of the amplifier, the cables being surrounded by a common outer shield.

Abstract: A displacement converter useful for pressure gauges and similar instruments, the converter including a displacement detector provided with a variable capacitor responsive to the displacement to be metered and a fixed capacitor insensitive thereto. Also included is an amplitude-controllable oscillator whose AC output is applied to both capacitors, means being coupled to the capacitors to derive therefrom electrical signals which are a function of their capacitance values. These electrical signals are fed to a control circuit to produce a control signal corresponding to the difference therebetween, the control signal being applied to the oscillator to govern the output amplitude thereof in a manner maintaining the control signal at a constant value.

Abstract: A signal generator for reducing the influence of fluctuations in flow rate distribution in a fluid passing through the flow tube of an electromagnetic flowmeter, which fluid intercepts a magnetic field therein to induce an emf which is transferred to the meter electrodes, thereby yielding a signal as a function of flow rate. To this end, the tube is provided with auxiliary electrodes disposed at arbitrary positions at which the potentials developed thereon are equal to each other when the existing flow rate distribution is symmetrical with respect to the flow tube axis, the auxiliary electrodes being interconnected.

Abstract: A probe submersible in a liquid to continuously analyze the concentration of a gas such as oxygen dissolved therein. The probe is constituted by a casing having an open mouth covered by a gas-permeable membrane to define a chamber filled with an electrolyte. Disposed within the chamber is a measuring electrode and a counter-electrode, the front face of the measuring electrode being slightly spaced from the rear surface of the membrane to create a gap that is filled by the electrolyte. Holes are formed in the measuring electrode to permit the passage of electrolyte between the front and rear faces thereof, the rear face being coated with an insulating layer to prevent an electrochemical reaction between this face and the electrolyte whereby the probe is then insensitive to dissolved gas contained in the electrolyte and responds only to gas contained in the liquid being analyzed. The walls of the holes may also be lined with an insulation layer for the same purpose.

Abstract: An electromagnetic flowmeter for measuring the flow rate of a fluid passing through a flow tube, the fluid intercepting a magnetic field established by an excitation coil supplied through an excitation circuit with a direct current or a current whose frequency is lower than that of a commercial AC power source. A DC reference voltage is derived from the excitation circuit which is either used in a feedback arrangement to maintain the excitation current constant or in a divider arrangement to correct for the adverse effects of fluctuations in the excitation current of the flow rate signal yielded by the flowmeter.

Abstract: A ratio meter adapted to determine the ratio of a first input signal representing the difference between two input voltages and a second signal representing the sum of both input voltages.

Abstract: A magnetic flowmeter whose electromagnet is excited by a low-frequency excitation current that is derived from an on-off alternating current whose frequency is higher than that of a commercial power line source, the on-off current being modulated by a low-frequency wave. A reference voltage-detecting transformer is interposed between the excitation coil of the electromagnet and an excitation current source. The primary of the transformer is constituted by a pair of windings wherein the excitation current is caused to flow in one direction in the first primary winding and a current produced by the counter-electromotive force generated in the excitation coil in every on-off transient of the excitation current is caused to flow in the opposite direction in the second primary winding.

Abstract: A technique for exciting the electromagnet of a magnetic flowmeter in which a fluid to be metered is conducted through a flow tube having detecting electrodes, the fluid intercepting a magnetic field established by the electromagnet to induce a signal in the electrodes indicative of flow in a high flow-rate range as well as in a low flow-rate range. In this technique, derived from the electrode signal is a control signal whose frequency is a function of the velocity of the fluid passing through the tube, the excitation current supplied to the electromagnet being governed by the control signal so that it has a frequency which is higher in the high flow-rate range and lower in the low flow-rate range.

Abstract: An electromagnetic flowmeter in which a low-frequency rectangular wave is supplied to the electromagnet coil of the flowmeter to produce an excitation current establishing a magnetic field which is intercepted by the fluid passing through the flow tube to induce a signal voltage in the electrodes disposed in the tube. This signal voltage is proportional to flow rate and is accompanied by an objectionable D-C noise component. To eliminate this noise component, the signal voltage is passed through a first high-pass filter, and to compensate for errors introduced by this filter, the signal voltage derived from the first filter is divided by a comparison voltage derived from the excitation current, but only after this comparison voltage passes through a second high-pass filter having essentially the same characteristics as the first filter.

Abstract: A magnetic flowmeter whose electromagnet is excited by a low-frequency excitation current, the flowmeter including flow tube electrodes yielding a flow rate signal. A reference voltage-detecting transformer is provided in the excitation circuit to produce a reference voltage that reflects fluctuations in the excitation current. Fluctuations in the flow rate signal as a result of fluctuations in the excitation current are eliminated by dividing the flow rate signal by the reference-voltage signal.

Abstract: An excitation system for a magnetic flowmeter provided with a flow tube through which the fluid to be metered is conducted, the tube having a pair of electrodes mounted at diametrically-opposed positions thereon and including an excitation coil to establish a magnetic field in the tube which is normal to the tube's axis and to a transverse axis passing through the electrodes, the fluid intersecting the magnetic field to induce a flow rate signal in said electrodes, the system including a full-wave rectifier coupled to a commercial power line source which produces sinusoidal a-c power whose wave periodically crosses a zero line. A switch is interposed between the rectifier and said excitation coil.

Abstract: Discloses a pneumatic controller having a proportional band altering unit, a proportional plus integral operation unit, a comparator and a manual-automatic transfer means, wherein the proportional band altering unit is combined with the proportional plus integral operation unit to provide a proportional band altering mechanism which limits input to prevent output of the comparator from being saturated whereby to enable the pneumatic controller to perform the transfer between the manual and automatic modes in a balanceless and bumpless manner.

Abstract: A process control system for multiplex operation of several process control loops. The system includes process input and process output units, analog and computer operation units and operator's interface stations, the exchange of process information between these units and stations being carried out by a time-sharing technique. The system is provided with a first data trunk through which process information through the data trunk is carried out in synchronism with address signals supplied to the address trunk in accordance with a cyclic control routine. Also included is a second data trunk which makes it possible at one's option to modify the cyclic control routine to select a desired mode of operation, the analog and computer operation units and the interface stations signalling whether operation in the manual control, analog control, or control mode is possible. State signals are generated at the operator's interface stations to the respective units to control their signal transmitting or receiving state.

Abstract: A resistance-to-current converter in which a sensing resistor, such as a resistance thermometer bulb for sensing changes in temperature, forms an arm in a resistance bridge which is periodically excited by a switching circuit interposed between a power supply and the input junctions of the bridge. The voltage produced at the output junctions of the bridge during the "on" and "off" excitation states are separately detected. The detected signal obtained in the "off" state is subtracted from that obtained in the "on" state to produce an output signal from which there is eliminated the error component resulting from a leakage resistance path coupled to said sensing resistor.

Abstract: A magnetic current meter adapted to sense the flow of liquid through an open channel to produce a mean flow velocity signal that is independent of fluctuations in the level of liquid in the channel. The meter includes a tube of insulation material so positioned in the channel that its longitudinal axis is normal to the direction of flow. Disposed in the tube is a rod having a coil wound thereon, the coil being excited by a low-frequency alternating current to produce an external magnetic field. A pair of electrodes are mounted on opposite sides of the tube on the outer surface thereof whereby the flow of liquid which intercepts the external field induces a voltage signal in the electrodes proportional to the mean flow velocity. The height of the meter exceeds the depth of the channel and is higher, therefore, than the liquid level regardless of fluctuations therein.

Abstract: A magnetic flowmeter whose electromagnet is excited by a low-frequency excitation current having an a-c component and a d-c component, the flowmeter including flow tube electrodes yielding a flow rate signal. A reference-voltage detecting transformer is provided to produce a reference-voltage proportional to the a-c component of the excitation current. Fluctuations in the flow rate signal as a result of fluctuations in the a-c component of the excitation current are eliminated by dividing the flow rate signal by the reference-voltage signal. In order to eliminate from the reference-voltage detecting transformer the unwanted magnetic flux generated by the d-c component of the excitation current, compensating means are provided to generate a counter magnetic flux, whereby saturation of the transformer core and the resultant distortion of the reference voltage signal are avoided.