A method and apparatus for near real-time in-situ soil solution measurements is presented. An outer sleeve is placed in soil where ionic concentrations of organic or inorganic species are to be measured. A porous section connects with the outer sleeve (the porous section initially loaded with distilled water) equilibrates with the solution present in soil pores to form a solution to be measured. The initial distilled water is displaced within the porous section by a removable plunger. After substantial equilibration of the solution to be measured within the apparatus, the plunger is removed and a removable probe replaced. The probe may be an Ion Selective Electrode, or a transflection dip probe. The probe then may be used under computer control for measurement of solution properties. The Ion Selective Electrode may measure nitrate (NO 3 − ) concentrations. The transflection dip probe may be read with spectrometer with an input deuterium light source.

In-situ soil nitrate ion concentration sensor

A voltage regulator for AC single phase and three phase systems. An output voltage is controlled by controlling a preset stepped addition to or subtraction from the input voltage. The controlled addition or subtraction is performed by a series injection transformer whose secondary is in series with the input voltage and whose primary is controlled by a microprocessor based switch matrix. The switch matrix imposes various voltage levels and phasing on the primary winding so as to produce a regulated system output voltage.

Voltage regulator for AC single phase and three phase systems

A protection circuit is provided for a tap switching line voltage regulator of the type which selectively switches in one of a predetermined number of taps on a winding of a transformer. The selective switching of the taps is controlled in response to the sensed load voltage to provide a regulated voltage to a load in the presence of a varying input line voltage. The tap switching line voltage regulator in response to the sensed load voltage controls the conductive state of a solid state series switching element in each of the switched tap lines. The protection circuit provides current limiting inductors in series with each of the solid state switching elements with all the inductors being wound on a common magnetic core. When switching from one tap to another tap, the tap switching line volage regulator in response to the sensed voltage operates to select an adjacent tap to the tap currently selected. Thus, tap switching proceeds in a sequential fashion up and down along the taps. The series inductors are wound on the common magnetic core such that the direction of the windings alternates between adjacent taps. Accordingly, the protection circuit provides a current limiting impedance to circulating currents that is four times the impedance to normal load currents. Accordingly, the circulating current caused by leading or lagging power factor operation is limited to prevent damage to the solid state switching elements.

Tap switching protection circuit

An autotransformer is connected to an unregulated voltage source, and serves as a supply transformer for a load. Interposed between this supply transformer and the load is the secondary winding of a regulating transformer, whose primary winding may be selectively coupled between various taps on the supply autotransformer winding. The primary winding of the regulating transformer is coupled to the desired points on the autotransformer winding by means of semiconductor switches, actuated when the system current waveform approaches zero.

Voltage regulator with zero current static switching between taps for a regulator transformer

A microwave oven for a camping or other vehicle includes a heating room in which an object is heating by applying microwaves thereto, a microwave guide to propagate the microwaves into the heating room, a magnetron to produce the microwave for the microwave guide, and a voltage supply device to supply the magnetron with an appropriate voltage. The voltage supply device includes a transformer to boost the three-phase AC voltage from an alternator mounted on the vehicle, and a rectifying circuit to rectify the three-phase AC voltage boosted by the transformer. The magnetron receives the voltage rectified. The heater terminal and other main terminal of the magnetron are connected to terminals of the battery mounted on the vehicle.

Microwave oven for vehicles

The control of thyristors used in alternating-voltage regulators employing synchronous tap changing is normally complicated when there are wide variations in load power factor. The modified form of tap changing circuit described here simplifies these control problems and because of the different operating mode produces less distortion in the output waveform. The essential feature of this circuit is that a tapped inductor carrying a controlled direct current is connected in the output circuit of the regulator. This inductor prevents tap-to-tap short circuits and effectively provides an additional output voltage level.

A Thyristor Alternating-Voltage Regulator

Regulator apparatus including static switching circuit having mid-tapped inductor

A probe assembly including an oxygen ion conductive solid electrolyte electrochemical cell is preheated under controlled conditions to a temperature equivalent to the temperature of a high temperature oxygen containing fluid such as a gas or molten metal prior to insertion of the probe into the fluid for measuring the oxygen concentration of the fluid. The preheating of the solid electrolyte electro-chemical cell coupled with the use of thermal shield elements within the probe assembly prevents physical deterioration of the solid electrolyte electrochemical cell due to the thermal shock produced when contacting the high temperature fluid.

Raymond Thompson

Papers

A Thyristor Alternating-Voltage Regulator

Regulator apparatus including static switching circuit having mid-tapped inductor

Apparatus for monitoring the oxygen content of high temperature fluids

Three-phase regulator systems

Firing circuit for controlling two circuit parameters