Abstract: An improved electrical appliance with short-circuit hazard protection includes a plug unit adapted to be connected to a source of electricity and a feed cord extending from the plug unit to the electrical appliance for supplying electric current thereto. The feed cord has a connector terminal by which the feed cord is rotatably or detachably coupled to the appliance. The appliance incorporates a first hazard sensor which detects an electrical hazard or short-circuit condition caused by moisture, water, or the like conductive medium. The plug units includes an interrupting circuit which disconnects the feed cord from the source of electricity in response to the detection of the hazard condition.

Abstract: A safety device adapted for use in a hand held tool for minimizing electrical shock from an AC power supply to a user includes a gound plane disposed inside the electrical tool, which, should the tool become immersed in water or become unreasonably wet, provides a path for electrical current, which energizes a solenoid which, in turn, disconnects the AC power supply. The safety device is encased in a cartridge or module. The safety device contains a power supply, such as a electret and/or a battery, that is independent of the AC power supply. Thus, the safety device can be tripped even if the tool is not plugged in or turned on.

Abstract: A modular water distillation apparatus includes a distillation unit which may be manually operated by adding water manually to the steam generator. The apparatus further includes an add-on holding tank and an add-on control unit which mounts to the holding tank and provides automatic control of the distillation unit by providing feedwater to the steam generator when the steam generator is deenergized and the holding tank is not full. The add-on control further includes a power receptacle for an add-on distilled water demand pump.

Abstract: The system is designed to shut-off the flow of liquid in a conduit, unattended, i.e., automatically, in the event of a liquid conduit rupture, liquid overflow, or the like. A float which carries a mercury switch is set over a recess formed therefor and into which liquid can flow and collect. The float rises with the collected liquid, and the mercury switch activates a solenoid valve which is interpositioned in a pressured-liquid conduit, to halt the flow of liquid through the conduit. The recess is formed in a lowermost portion of an area in which the subject conduit is sited.

Abstract: An electro ballistic escape sequencing system is actuated only by the seat initiators. Current entering the system by any other means will see only open circuits. A pressure sensitive switch is provided in each circuit subject to outside interference and is normally in the open position. When ejection is required, pressure from one of the seat initiators activates the thermal battery and closes all circuits required for ejection.

Abstract: A system to be used in combination with an air conditioning assembly and designed and structured for the detection of collected condensation at a predetermined level within a collection facility associated therewith and prior to actual over flow and also the detection of any leakage from any of the collection facilities or various plumbing components throughout the air conditioning system such that the detection of either excess collected condensation or leakage serves to shut-down the air conditioning assembly. The subject system may also be structured to restart the air conditioning assembly automatically once a level of collected condensation has receded or any leakage has been alleviated.

Abstract: A carpet mat switch system is provided in which a person when stepping on a mat structure will electrically activate a lamp, burglar alarm, program talking clock or any other appliance connected thereto. A manual override is also provided to either turn off an actuating unit in the mat structure or manually operate a switch therein without stepping on the mat structure.

Abstract: The apparatus is of the kind comprising a flow detector supplying, in the absence of flow, a stop down signal for the pump, a pressure detector supplying, for a predetermined minimum value of the pressure, a start up signal for the pump, and impeller means for the pressure detector, and is featured by the fact that the pressure detector comprises a movable part (1, 2) which is integral with a membrane (3) closing a cavity (3b) communicating with the hydraulic network, and a fixed part (4, 5) arranged in the apparatus body at the displacement position of the movable part (1, 2), the impeller means for the movable part of the pressure detector are constituted of a spring (8) mounted between the said movable part (1, 2) and the apparatus body (9), the flow detector comprising a part (6, 7) which is movable in the vertical direction and performs the function of gravity closing valve, and a fixed part (4, 5) which is arranged in the apparatus body.

Abstract: The liquid level in a tank is determined by measuring the current supplied to an elctromagnet from which a rod having a specific gravity greater than that of the liquid is suspended in the liquid.

Abstract: A liquid level control in a refrigeration system operates a solenoid valve to maintain the level of liquid refrigerant in a vessel within a range defined by predetermined lower and upper liquid levels, sounds an alarm if the upper level is exceeded and stops a pump if the lower level is violated. The control comprises a float assembly and a switching assembly. The float assembly comprises a float chamber connected to the vessel, a float ball therein, a vertically extending float rod connected to the float ball and movable along a vertical path, and a pair of spaced apart stop members on the float rod disposed within the switching assembly. The switching assembly comprises a switch actuator permanent magnet, having magnet poles at opposite ends, slidably mounted on the float rod between the stop members and movable thereby along the said path.

Abstract: A safety device to protect a piece of domestic electrical apparatus connected by means of a flexible supply lead to a plug to be attached to a conventional mains outlet. Between the pins of the plug and the exposed electrical working components of the apparatus is provided an on-off switch which will isolate the electrical operating components from the mains supply when the switch is in the "off" position. Sensor means are positioned within the piece of domestic electrical apparatus adjacent any exposed electrical components and control means for detecting a path of conduction between the sensor means and those exposed electrical components. Magnetically controlled release means including a permanent magnet and an electrically induced magnetic field in opposition thereto, preferably a DC motor provides movement when energized by the control means when the latter detect a path of conduction.

Abstract: A fail-safe immersion detector has a reset button which may be operated to return an appliance to operation after an immersion-caused short circuit has disappeared. However, if the short circuit remains, an operation of the reset button has no effect. Therefore, the user cannot defeat the fail-safe detector by the expedient of taping or otherwise holding down the reset button. A rocker switch enables a testing of the immersion detector, to be conducted to either side of the A.C. power line while preventing a short circuit across the line if an effort is made to simultaneously conduct tests to both sides of the line. Two test wires extend from the detector through the power cord to the appliance, where they are joined. The immersion detector operates via one of the two wires. The rocker switch conducts the test via the two test wires in series. Therefore, the rocker switch controlled test verifies the integrity of the one test wire.

Abstract: A high-voltage switchgear having a fixed and a moving contact member includes a hydraulic drive for operation of the moving contact member having a piston and cylinder configuration with a piston coupled to the moving contact member. A fluid reservoir configuration supplies fluid under pressure to the piston for driving the piston. A compressor unit at ground potential charges the fluid reservoir configuration. Electrically-insulating, pressure-resistant lines respectively connect the compressor unit with the piston and cylinder configuration and with the fluid reservoir configuration. The piston and cylinder configuration and the fluid reservoir configuration are disposed spatially close to and at the same electrical potential as the moving contact member.

Abstract: An electronic relay control circuit is provided for liquid cooled electric power transformers. The control circuit senses the rate of change of internal tank pressure and operates its relays in response to a sudden pressure increase. Relay control connections are provided for operating transformer trip and annunciator circuits. The relay response is field adjustable.

Abstract: An improved capacitance bridge type liquid level control system for use in refrigeration applications is disclosed which provides improved apparatus for sealing the probe in its mounting and for insulating same against the condenser reservoir stand pipe in which it is mounted. Improved sealing between the probe and probe body is accomplished through an annular PTFE seal which when compressed pushes inwardly to seal a tubular PTFE insulation against annular ridges in the side of the probe rod proper. The improved probe rod shape also maintains a proper stabilized axial alignment between the probe rod and the probe body.

Abstract: A ground fault interrupter (GFI) circuit is wired to a main circuit breaker panel. A first output of the ground fault interrupter circuit provides electrical current to a solenoid valve that controls the supply of cold water to a conventional hot water heater. The solenoid valve is held in its open position by 110 V. alternating current and is closed by spring biasing means when the current is cut off. The other output of the GFI circuit provides 110 V. alternating current to a leak detector. A leak detecting system directs leakage to a collector wherein the presence of water in the collector completes the circuit between the hot wire and ground of the second outlet. When the circuit is shorted out to ground by the presence of water the GFI circuit is tripped at the main circuit breaker panel and simultaneously cuts off current to the solenoid valve controlling the flow of water to the heater permitting the spring to bias the valve shut and preventing any water damage due to leakage.

Abstract: Apparatus for producing output signal changes corresponding to fluid pressure changes includes:(a) a transducer responsive to applied input pressure changes to produce capacitance changes at a variable capacitor,(b) a first circuit to produce a cyclic wave, and connected with the variable capacitor,(c) a second circuit including a switch to connect the capacitor to ground when the cyclic wave is at a first level, thereby to charge the variable capacitor, and to connect the variable capacitor to a second capacitor when the cyclic wave is at a second level, whereby the charge becomes distributed on the variable and second capacitors, and whereby a sawtooth signal is produced at a junction associated with the capacitors,(d) an operational amplifier electrically coupled with that junction for integrating the sawtooth signal to produce a first output voltage,(e) the first circuit including a voltage controlled oscillator having an input side coupled with the output side of the operational amplifier thereby to prod

Abstract: An immersion detector circuit interrupter having a sensor located around the electrical components of an appliance and a relay for interrupting the delivery of alternating current to the appliance whenever the sensor conducts a current at a predetermined voltage. The sensor is connected in series with a zener diode, a regular diode, the coil of the relay and to another two diodes which are connected to two alternating current conductors which provide electrical current to the appliance. The sensor is generally always at an electrical potential opposite or substantially different than the electrical potential of the electrical components at any particular point in time.

Abstract: Basement flooding due inter alia, to drain overflow or sump pump failure is a common problem. An apparatus for solving the problem includes a cover for closing a basement floor drain, a tubular casing extending through the cover into the drain, a pair of spaced apart conductors in the casing for completing an electrical circuit when water rises through the open bottom end of the casing to a predetermined level, and a control circuit connected to the conductors and to a solenoid valve in the building water supply pipe for closing the latter, so that no additional water enters the drain to exacerbate an already bad condition. A second pair of spaced apart conductors on the floor of the basement is coupled to the control circuit to give the same response in the presence of floor moisture. An audible alarm is sounded as part of the response to detected water.

Abstract: Well testing apparatus for running on a single-conductor electric cable for gathering reservoir information, the apparatus utilizing two pressure gages and a valve, the valve being landable in a downhole receptacle and being operable to shut in the well or to open it for flow by tensioning or relaxing the electric cable, one of the gages sensing well pressures below the valve and the other gage sensing pressures above the valve, both pressure gages sending signals to the surface corresponding to the pressures sensed thereby both while the well is shut in and while it is flowing, the pressure signals being processed by surface readout equipment for real-time display, recording and/or printout, the apparatus including, if desired, a temperature sensor which sends appropriate signals to the surface which not only indicate the well temperatures sensed but the temperatures are used by a computer and its software to automatically correct the pressure readings for temperature affects.

Abstract: An immersion detection current interrupter circuit with an electric latch for use in small electrical appliances. A sensor wire is positioned within an appliance to sense current leakage when in contact with a conductive fluid. A relay or solenoid connected to the sensor is positioned between the load leads in a latch circuit. When the sensor detects a leakage current, it causes a two-pole double-throw relay to latch, breaking the load lines beyond the relay. The relay will remain latched until the power cord is unplugged or reset by a switch which opens and closes the power lines. Once the component has latched, the maximum leakage current will be limited by the voltage drop across a diode.

Abstract: A pneumatic circuit pressure control device including an electronic comparator for comparing a transducer generated pressure signal from the pneumatic circuit and a desired pressure signal from a desired pressure input generator. The comparison circuit selectively actuates a solenoid-actuated valve which controls the pressure in the pneumatic circuit. Preferably, the solenoid of the solenoid-actuated valve produces an electromagnetic field for electromagnetic induction of a circuit which oscillates the solenoid-actuated valve to produce a variable orifice-like effect when small changes in pressure are demanded by the comparator circuit.

Abstract: A liquid level sensor and controlling assembly disposed and mounted in direct communication with a reservoir of liquid to be monitored and including a float structure connected to an elongated stem formed of magnetic material which is disposed to selectively move, in accordance with the movement of the upper surface level of the liquid between a primary coil and a secondary coil. A constant voltage supplied to the primary coil results in a magnetic flux and a voltage being induced into the secondary coil based upon position of the magnetic material stem relative to the secondary coil thereby determining that the induced voltage in the secondary coil is directly related to the level of the liquid since the position of the magnetic stem within the secondary coil is controlled by the level of liquid within the reservoir.

Abstract: A water pump control system, such as for a boat, including a battery operated main motor-and-pump unit and a backup motor-and-pump unit. A pump turn-on transistor operates a relay to turn on the main motor-and-pump unit when the water level rises to a high level. A touch switch may be used to turn on the pump turn-on transistor independent of the water level. A pump turn-off transistor, which is turned on by the relay, keeps the main motor-and-pump unit on until the water level drops to a low water level. A backup motor-and-pump unit comes on if the main motor-and-pump unit has not come on after the pump turn-on transistor has been turned on.

Abstract: A motor vehicle suspension control includes a solenoid actuator having an actuating coil connected in series with a transistor across an electric power source and circuit protection apparatus for the transistor. The voltage across the transistor is monitored, after a short time delay following turn-on, as a signal indicative of excessive current therethrough. If the signal so indicates, the transistor is turned off for a period of time and then turned on again for another try. This continues for a predetermined maximum number of attempts. Specific clocked digital circuitry is disclosed for controlling the operation and producing the different required time delays or counts.

Abstract: The invention is in the field of electrical switching. The contactor includes a control member (5) which moves in translation and is placed between two bars (12) and (13) made from an electrically conducting material. The control member includes a monobloc part interposed between the two bars and has bearing surfaces (5', 5") enabling the control of the pivoting of the bars about axes perpendicular to the translation axis of the control member (5), to produce a sequential opening or closing of one set of pairs of contacts (8, 11) and of another set of pairs of contacts (9, 10). The invention is applicable to the control of the electrical powering of a pump to maintain the pressure of a fluid within a predetermined range.

Abstract: An improved automatic train-line air brake pressure monitoring system includes circuits that emulate an automatic brake valve and cause an automatic brake manifold release whenever a four psi increase in pressure is sensed. The system includes a pressure sensor amplifier (10) which provides a signal proportional to the sensed pressure in a brake pipe. This signal is tracked by a peak hold circuit (12) that stores the peak value of the signal. The output of the sensor amplifier is subtracted from the output of the peak hold circuit in a subtractor (14) to provide a difference signal. The difference signal is tracked by a reduction hold circuit (22) which stores the minimum value of the difference output from the subtractor. An increase in measured pressure from the stored minimum value is compared in a comparator (24) with a reference value representing the four psi level, and when the increased pressure exceeds the reference value, a system reset is generated.

Abstract: An electrohydraulic switching device for emitting electric control signals in dependence on supplied pressure signals. The switching device has a housing wherein a piston pressurizable by the inlet pressure is arranged so as to be axially displaceable. The piston is spring-loaded against the inlet pressure by means of a compression spring arranged between a spring plate and a guide means. The spring plate is secured at the piston by means of a snap ring, and the switching device has an actuating plate for actuating an electric switching mechanism. The actuating plate is positively connected with the piston, with the compression spring at its end facing the switching mechanism being axially guided by the guide sleeve.

Abstract: Hand-held electrical apparatus having an electrical detector in the form of a conductive sensor adjacent to any exposed electrical part so that if the apparatus becomes wet or damp the water will form path of conduction between the exposed electrical part and the sensor. A conductive path from the sensor forming part of the supply lead to the plug, and the plug comprising normally closed mechanical switch at least in the live line from the mains supply to the supply lead to the apparatus and a control circuit connected to the said sensor by the conductive path which open the switch as a result of the conductive path having been formed from the exposed electrical part because of the presence of moisture. The switch comprises a length of wire holding electrical contacts closed against the action of a spring. The control circuit fuse the wire, however, to allow the spring to open the contacts when the conductive path is established.

Abstract: There is disclosed an electronic float switch circuit which employs simple immersion probes, one of which is associated with a high fluid level and the other with a low fluid level. Each of the immersion probes operates in conjunction with an oscillator, a detector and a comparator. Essentially, when the associated immersion probe is immersed in a fluid, the oscillator ceases oscillations which therefore provides a first low voltage level via the detector to the comparator to therefore change the state of the comparator. The comparator associated with the high and low level probes operate to set and reset a DC flip-flop which in turn controls an opto-isolator device to trigger a triac. The triac operates the pump. When the fluid level reaches below the level of the low probe, the circuit is disabled allowing the vessel again to be filled with water to allow the pump to operate between the high and low levels by means of the electronic circuit.

Abstract: A monitoring assembly (20) which has a plurality of sensors (24) arranged in spaced relationship along a body (23) which may be suspended from a coded multicore cable (25) in a reservoir to monitor liquid levels therein. Each sensor (24) is connected to a respective coded core (43) of the multicore cable (25) such that any sensor (24) may be selectively coupled to remote control apparatus.

Abstract: A trimmable microminiature force-sensitive switching device for detecting the state of external conditions, such as pressure, acceleration and temperature, is disclosed. The device includes a silicon substrate having a reduced-thickness, deflectable member adapted to change its deflection in response to changes in the external condition to be detected. Increasing deflection of the member establishes electrical contact between a common contact and first one, then progressively more, spaced electrical contacts of a plurality of switches. Each of the spaced electrical contacts is connected to a common terminal. Trimming of the switching device is accomplished by application of a preselected external force, such as pressure, that causes the deflection of the deflectable member and the closing of one or more of the switches.

Abstract: A fuel delivery system which includes a fuel pump and a dc motor, which are preferably contained within a unitary housing. A pressure-sensitive switch, which is either contained within the unitary pump/motor housing or as a separate structure, includes a movable contact positioned within a housing so as to form a first chamber for receiving fuel under pressure and a second chamber for venting to atmosphere. A spring urges the movable contact against a second contact for applying electrical power to the pump motor. When the pump output pressure exceeds the force exerted on the movable contact by the spring, electrical conduction between the switch contacts is broken and motor power is interrupted. Current to the pump motor is thus pulse-width modulated as a function of pump output pressure, fuel demand, and the adjustable force exerted by the pressure switch spring.

Abstract: A circuit arrangement for the electro-thermal measurement of the filling level in the tank of a motor vehicle which includes a resistance sensor adapted to be heated during a heating time of a sampling period. In order to assure that the resistance sensor can cool off again within the sampling period even after several starting attempts of the engine, the sequence control of the circuit arrangement connected with the voltage supply is connected with a further voltage source from which, after turning off the voltage supply, the sequence control is continued to be supplied with voltage by a switching circuit over a time interval which corresponds to the termination of the sampling period.

Abstract: The present invention teaches a system for protecting people and property against electrical shock which includes immersion detecting circuits, broken wire test circuits, electromechanical circuit breaking means including coil/plunger arrangements, and relay circuit breaking mechanisms cooperative with associated circuitry, all of which are able to be incorporated as a system wholly within the load (appliance) and its associated cord set (including a "plug").

Abstract: A leakage detecting device for electrical appliance is provided with electrodes (17) for detecting a state in which an electrical appliance such as a hair dryer is submerged in water. When the electrodes (17) are in a short-circuited state, relay means (3) is driven to open a contact (7). As a result, supply of the power supply voltage from a commercial power source (1) to the loads such as a motor (15), a heater (16) and the like is stopped so that an accident due to leakage can be prevented in such cases as a case in which the electrical appliance has been dropped into the water.

Abstract: The liquid tank comprises a container (1) containing a level gauge (3), an element (9) indicating the position of the gauge (3) and located outside the container (1), and a filling duct (2) for the container (1) fitted with an electro-magnetic sluice gate (10), a container (1) with a float (3) which modifies the resistance (9) as a function of its level. The value of the resistance (9) is monitored as a function of the time starting from the start of the filling operation so as to detect any fault inside the container (1).

Abstract: In a liquid level detecting device for fuel or oil in a small size boat, a liquid level detecting switch turned on and off in accordance with a vertical movement of a float provided in a tank and a liquid level warning device are connected in series to a power supply circuit from a generator of an engine.

Abstract: The invention concerns a bilge pump control system. Sensing of water level in the bilge is accomplished by the conduction of current (on the order of one milliampere) between two stainless steel probes. The probes are mounted in a triangular package which is placed in the boat bilge. When immersed, a conduction path is provided between the probes. One edge of the package is aligned with the probes to enhance water run-off. An associated circuit is activated when the conduction path is present (when the probes are immersed) which operates the bilge pump in a time-hysteresis fashion.

Abstract: A pressure sensor probe has a first port connectable to a relatively low pressure source in a compressor crankcase and a second port connectable to a relatively high pressure source at the output of an oil pump. A shuttle is slidably disposed in a bore and has a first end which closes the first port when the difference in pressure between the two ports indicative of normal operation exceeds a selected value determined by the relative areas of the shuttle exposed to the respective pressures and by a coil spring which biases the shuttle away from the first port. A passage is formed between the shuttle and the bore leading from the second port to a force receiving surface on the high pressure side of the shuttle. The length and cross sectional area of the passage is selected to provide a desired dampening or time delay between the high pressure source and the force receiving surface. A control circuit includes a reed switch whose state of actuation is dependent upon the position of the shuttle.

Abstract: An electric control element, and more particularly a control that is responsive to a liquid level indicator and is operative to prevent a fuel tank from inadvertently running dry.

Abstract: A moisture sensing detector of snow, sleet, ice and rain. The detector includes a sensing probe and coacting control circuitry for receiving the moisture signal from the probe and actuating associated equipment such as, for example, a railroad switch heater. The probe includes sturdy substantially elongated electrically charged aluminum electrodes spaced apart a very small distance (1/8" gap for example) by fiberglass strip insulation. Any moisture (even a drop of water) bridging the small gap completes a circuit between the electrodes which triggers the control circuit into actuating the railroad track switch heater or any like equipment. The electrodes are substantially elongated to provide a large sensing area. A heating unit is secured to one electrode to heat the entire length of the probe thereby melting any ice, sleet and snow (since they do not conduct an electrical current) thus permitting the probe to detect resultant moisture.

Abstract: The invention relates to an electrical control unit for controlling the speed of a pump motor of a pressurized fluid supply system having a tank. A pressure responsive switch unit connected to the tank has at least three switch positions corresponding to pressure levels in the tank. The switch unit outputs three different voltage levels to a transistor and circuitry responsive to the three voltage levels utilizes this input to control the speed of the pump motor. The circuitry includes an integration capacitor and the effects of charging and discharging the capacitor in accordance with the three voltage levels produced by the switch unit are utilized for controlling the pump motor.

Abstract: Servoed accelerometer with isolated voltage torquing having first and second grounds, a servoed accelerometer having a torque coil, and an amplifier for driving said torque coil. The amplifier has inverting and non-inverting junctions. The second ground is coupled to the non-inverting junction of the amplifier. A torque signal supply is coupled to the first ground. A transformer is provided for coupling the torque signal supply to the non-inverting junction of the amplifier and serves to isolate the torque signal supply from the non-inverting input of the amplifier so that the amplifier and polarity of the torque signal are preserved.

Abstract: In a fluid level measurement system for the measurement of a level of fluid in a vessel the electrical impedance of a first conduction path between a central rod electrode and a surrounding cylindrical electrode and the electrical impedance of the second conduction path between the cylinder and the vessel are established. The first conduction path is restricted to be below the minimum fluid level by an insulating coating on the rod. The second conduction path varies with the fluid level. An output signal is extracted from the electrodes potentiometrically which is indicative of the fluid level. The signal may be linearized by application to a circuit having a matched non-linear transfer function. With this arrangement, a continuous output signal indicative of the fluid level is produced which is not subject to errors due to changes in fluid resistivity.

Abstract: A pressure switch having mechanical and solid state components enclosed within a common cover. The mechanical components and the cover are secured to a support. The mechanical components include a snap acting switch having terminals connected to an alternating current source and an alternating current motor and a diaphragm that operates the snap switch in response to pressure changes in a fluid system. The cover includes a dividing wall that separates an internal cavity within the cover into two chambers with a rear chamber providing an enclosure for the mechanical components and the front chamber providing an enclosure for the solid state components that include means for detecting the motor current and voltage and a microcomputer. The dividing wall has spaced openings for connectors that provide a separable electric connection between the terminals in the rear chamber and the solid state components in the front chamber.

Abstract: An automatic cup-filling control arrangement for beverage dispensers utilizes the spray or mist of liquid droplets, formed by flowing beverage striking beverage already in the cup, to complete an electrical circuit. This electrical circuit extends from an electrically conducting member, such as an actuating lever, to beverage flowing through a dispensing valve. When the mist of droplets permits a pre-established magnitude of current to flow between the actuating lever and the flowing beverage, which occurs when beverage in the cup reaches a pre-determined level, dispensing of the beverage is terminated.

Abstract: In a method for the electrothermal measurement of level which is compensated for ambient temperature and in which a resistance probe is heated with a constant current in each case during a heating time, a comparison is effected between a first variable formed from at least one probe voltage at the start of the heating time and a second variable formed from at least one probe voltage at the end of the heating time. The forming of at least one of the two variables is effected in accordance with a time function. In order to reduce the influence of disturbing effects and, in particular, voltage noise pulses, the first variable is formed by integration of the probe voltages from the start of the heating time up to the middle of the heating time. The second variable is then formed by integration of the probe voltages from the middle of the heating time until its end. The two integrals are then subtracted from one another to produce a measurement value.

Abstract: An improved low liquid level float control apparatus particularly adapted for use in vessels or tanks containing a fluid of the type utilized in liquid vending machines is disclosed. An electronic control unit has a probe section extending downwardly therefrom containing a reed switch, which is activated by the passage of a first magnet located in the lower portion of a float vertically along the probe section. A second magnet is secured along the upper portion of the float. Metal stops are provided along the probe section to determine the range and movement of the float and to effect a time delay, thus reducing the possibility of intermittent on-off operation of associated pump elements.

Abstract: The oil detecting switch includes a light oil float switch, a water float switch and a heavy oil float switch. When the light oil float switch is closed, a relay is activated energizing a light oil indicator light and its associated coil. The coil is part of a relay which inhibits pumping action. When the water float switch is activated, the inhibiting relay is bypassed so that pumping action can continue. When the heavy oil float switch is activated and closed, a relay is activated which energizes a heavy oil indicator light and its associated coil. The coil is part of a relay which inhibits pumping action. The light oil indicator light, its associated coil and the water indicator light are bypassed when the heavy oil float switch is activated. The status of the float switches is monitored by an analog-to-digital converter associated with a Remote Monitoring System Transmitter.