Measuring probe and a device for measuring the level of conductive material
(57) Abstract:Usage: determining whether the location of the probe conductive material in granules or in liquid form. The inventive measuring probe contains a first electrode separated from a second electrode electrically insulating porous gas-permeable material, means for conducting gas through the gas-permeable material, and means for communicating the first and second electrodes with a source of electrical energy, when the gap between the electrodes is electrically shorted by a conductive material. 2 S. and 11 C.p. f-crystals. 3 Il. The invention relates to the field of measuring probes designed to determine whether the location of the probe conductive material in granules or in liquid form.The probe can be used to generate an electrical signal indicating that the conductive material in granules or in liquid form is present at least at the level of the probe. This signal can be used to determine the amount of granular or liquid material in the container, the location of the probe, given the speaker of the location of the probe electrically conductive material in granules or in liquid form contained the first electrode and the second electrode, placed at some distance from the first electrode, and means for connecting the first and second electrodes for supplying electric energy, so that, when the gap between these electrodes is electrically shorted by conductive material, the electrical circuit of the probe is formed according to the invention, the first electrode is separated from the second electrode placed in between electrically insulating porous gas-permeable material and a means for passing the gas from the probe through the gas-permeable material between the electrodes.In the case when the amount of bulk material consisting of conductive granular substances, falls below the level of the probe, this bulk material may remain on the electrodes in the form of threads or grains adhering granular substance that ensures the existence of residual conductive bridge between the electrodes. The presence of such residual bridge can cause spurious signals in the electric circuit connected with the electrodes, and the issuance of false testimony that the amount of bulk material is still reaches level so the probe can be self-cleaning. In the case when the probe is used to determine the presence or absence of conductive fluid at the level of the probe and the liquid level drops below the electrodes, the gas flow from the probe can blow away or dry any liquid residues, resulting in liquidated liquid conductive path between the electrodes.The invention is further explained by means of examples with reference to the accompanying drawings, in which:
Fig. 1 depicts a lateral projection (partial sectional view) of the measuring probe with the gas source, shown schematically, and an electric circuit according to the invention; Fig. 2, a modification of the probe shown in Fig. 1, according to the invention; Fig. 3 variant execution and layout multiple probes, each of which is shown in Fig. 1 with the gas source and the electronic indicator circuit.Made of heat resistant material measurement probe 2 (Fig. 1) contains the electrode 4, which in turn includes a tube 5, round in cross section, around which is placed a concentric cylindrical electrode 6. These electrodes 4 and 6 may be made of any suitable teploty, formed in substantially a flat plane 8, which leaves an annular skirt 10. Two electrodes 4 and 6 are separated from one another heat-resistant non-conducting electricity gasket 12, which has a mechanical strength. The strip 12 may be a ceramic. Possible ceramic material for the insulating gasket 12 is SCHUMALITH SC (trademark), Filter Candle, Mark 5, which comes Schumacher Filters Ltd. of Parkway Industrial Estate, Sheffield, England.The strip 12 has a cylindrical shape, and its cylindrical surface 14 attached to the inner surface of the skirt 10 by using, for example, heat-resistant adhesive material. The electrode 4 is placed in the axial hole 16 in the strip 12 and attached thereto, for example, using a heat resistant adhesive material. The material of the strip 12, is a porous gas-permeable substance, consisting of many interconnected cells or cavities, forming passages through which the gas stream passes through the strip from one end 18 to the opposite 20. The end surface of the strip 18 is shown flush with the end 22 of the tube 5, but such an embodiment is not the only and the lower end 24 is Astelin. The end surface 18 of the strip 12 is at a distance from the inner surface of the unit cover 8, so that the inside electrode 6 remained narrow cylindrical lumen 26. The electrode 4 includes next tee 28 and tube 30 and 32. The ends 34, 36 and 38 of these tubes are attached to the branches of the tee using a gas-tight connections, including conducting electricity olives, secured in place with nuts 40, 42 and 44.Tube 5, the electrode 6 and the spacer 12 may be in the cross section of not only the round.Heat resistant electrical cable 46, for example, RYROTENAX (trademark) passes through the tube 5 and the tee 28 with good insulating gap. The cable 46 has a heat resistant outer shell, for example, stainless steel, secured in gas-tight heat-resistant adapter 48 in the end 50 of the tube 32. The connection 48 may be a soldered connection. Inside electrode 6 is lived 52 cable, it comes out of the sheath of the cable and soldered with hard solder at the point 54 section 8 of the electrode tip. Between the outer jacket of the cable 46 and the conductive housing posted by mineral insulation, for example, magnesium oxide.When the probe 2 is in operation, the tube 30 waspresented pressure environment, surrounding the electrodes 6 and 4. Thus, gas from the source 58 flows along the tube 30 and through the tee 28 and the tube 5 enters into the gap 26 from which it passes through the porous pad 12 to exit end surface 20. The gas exits the strip under pressure, producing the effect of an explosion near the end surface 20. The gas pressure in the gap 26 can have a value whose magnitude is within the specified limits and exceeds the ambient pressure around the electrode 6. The pressure difference in the gap 26 and the ambient pressure around the electrode 6 may be about 20 psi (about 1.4 kg/cm2). To ensure that a given pressure difference arising between the gap 26 and the ambient atmosphere around the electrode 6, not only is there pressure at the outlet of the gas source 58 in accordance with a given pressure value, but can be provided by a special device in the probe 2, to provide a given pressure difference, for example, the probe can be placed a device that restricts the flow of gas to provide the desired pressure drop through the restrictive device.In Fig. 1 restrictive device is depicted in the form of plastic flow of gas, placed between the two parts of the tube 30.As an alternative means of limiting the flow of gas, for example, instead of the plate 60 or gate 63 or in addition to the stated means may be proposed gas-permeable or porous insulating gasket 12, which provides the desired pressure difference between the end surfaces 18 and 20 of the strip 12. It is desirable that the permeability of the insulating strip 12 was such that the gas stream emerging from its end surface 20, was almost homogeneous over the entire surface 20.As the gas source 58 may be used, for example, nitrogen. Gas supply of the probe 2 may be continuous. The electric power source is also connected to the probe 2. This source may be a constant current source 64, when one pole is connected to the conductor 52 of the cable 46, and the other pole connected to the electrode 4. This connection option to the electrode 4 shows the pipe 30 as an example.To detect the presence of conductive material in free-flowing granular material, the probe is placed so that the granular material could accumulate and such quantity that simultaneously confiscated, granular material forms a conductive bridge between the electrode 6 and the electrode 4, closing thus the circuit 66 includes a detection device, such as a voltmeter, which signals that the circuit is closed. This means that some of the probe 2 is as much of a granular material, which it reaches at least the level of the end 24 of the electrode 6 above the level of the baseline, which is a measure of how much of a granular material is above the baseline. If you remove part of the bulk granular material, so that the remaining amount held amount commensurate with the volume, when the matter was below the level of the end of the electrode 24, the continuously flowing through the surface 20 of the strip 12, the gas will blow away any particles or threads sticky granular material, which may have a tendency to remain and form a bridge between the electrode 6 and the electrode 4. The chain 66 opens, and the detecting device 68 will register that the level of granular material, which may still remain in the vicinity of the probe 2, is located below the end of the electrode 24. Because of the probe 2 is continuously supplied gas, which acts as a washing liquid, predotvraschaet is the more than it is actually.If the probe 2 to be used for level measurement of conductive liquid when the liquid level drops below the level of the end 24 of the electrode, continuously flowing the gas will blow away or dry out the liquid remaining on the surface 20 of the strip, and thus removes the cause of the existence of the conductive paths between the electrodes 4 and 6.To determine the level of granular material or liquid located between vertically spaced upper and lower limits, can be used many probes 2, are configured on different vertical levels on the vertical interval between the limits.In the device shown in Fig. 3, the number of probe 2 is used to measure the level of charred substances accumulated in the lower part 70 of the tubular device or hydrogenator 72 with the upper part, in which small pieces of coal hydrogensource or react in a hydrogen gas environment with the formation of methane, waste coal falls in the form of pellets burned substances in direction 1 and is collected in the form of a loose mass of granules sintered substance in the lower part 70, where it is removed through the opening 74. In In Fig. 3 probes labeled 202, 302, 402, 502, 602 and 702. In hydrogenator these probes are at a high temperature, for example several hundred degrees Celsius. Tube 30 probes are in electrical contact with conductive material, forming part of the wall 76 72 installation. The cable 46 from the respective probes 202, 302, 402, 502, 602 and 702 are used as inputs of the respective amplifiers 278, 378, 478, 578, 678, and 778. All these amps are essentially the same. The energy source 64, such as a constant current source connected to the amplifiers, as well as conducting material, forming part of the wall 76 to form an electrical circuit that includes probes. When conductive charred substance closes the gap between the two electrodes 4 and 6 of any of the probes, an electric current is passed through the probe, that is, an electrical signal is sent to the corresponding wire 46 that serves as the input of the corresponding amplifier 278, 378, 478, 578, 678, and 778.Four probe 302, 402, 502 and 602 are positioned to measure the accumulation of charred substances in the lower part 70 hydrogenator, and depending on the degree of accumulation level charred substances will be between the upper and lower limits of II and III is shipped one or more. Because the probe 202 is located below the lowest level charred substance III, he is always immersed in a charred substance that forms a continuous conductive bridge between the electrodes of the probe. Thus, the electrical signal on the conductor 46 of the probe 202 (which is a reference probe having a conductive substance) always has a value corresponding to the presence of charred substances defined by the probe. The electrical signal from the probe 202 is input to the amplifier 278, where it is amplified and then the amplified signal is supplied to the input wires 280 compares the device 82. Comparing the device 82 may be a differential amplifier. The reference signal generator 84 delivers the reference setpoint signal to the input 86 comparing device 82. Comparing unit 82 compares the amplified signal at the input 280 with a reference signal, and, if they differ, comparing the instrument displays on the wire 88 adjustable amplifying a signal which is a function of the difference of the signals on the wires 280 and 86. The gain of the signal on the wire 88 changes the gain produced by the amplifier 278 to make an amplified signal on the wire 280 is equal to the reference signal on conductor 86. When this signal is allowing the signal on lead 88 is also fed to amplifiers 378, 478, 578, 678 and 778 to control the gain value to each of these amplifiers had the same gain as the amplifier 278.If all of the amplifiers have the same gain, it's a guarantee that the signal on the wire 46 from any of the probes 302, 402, 502, or 602 recognized and attests to the fact that he filed due to the lack of bridge of charred material between the electrodes of the probe or due to the fact that charred substance is simultaneously in contact with the electrodes. Charred substance may have a very high electrical resistance and low conductivity, such that even if charred substance is simultaneously in contact with both electrodes of one of the probes, electrical signal on the corresponding wire 46 will be weak and it will be difficult to determine when the electrodes are not connected by a bridge made of charred matter. However, it is known that the probe 202 is always immersed in a charred substance, so that the value of the output amplified signal on the wire 280 shows the magnitude of the signal, which indicates that the charred substance is at the level of the probe. Thus, when the amplified signal on the output wire 380, 480, 580 or 680 significant with the level of the corresponding probe 302, 402, 502 or 602.Probes in hydrogenator are exposed to high temperature. This may cause some decrease in the insulation resistance between residential cable 52 and the electrode 4. Therefore, the signal on the wire 46 from the probe 302, 402, 502, or 602 may be substantially in error, he may specify that charred substance is at the level of the probe. Because the probe 702 is never immersed in a charred substance, then, as noted above, any signal on the wire 46 with this design is perceived as the result of a decrease in insulation resistance. It is possible that a similar decrease the insulation resistance of the probes 202, 302, 402, 502 and 602. Thus, if there is a decrease in the insulation resistance in the probe 702 (which is a probe error reference signal), the signal on the wire 46 from this probe has an electrical quantity that is a component of the electrical signal magnitude at the specified wire 46 any other probe. To resolve the enhanced value of this component, the output on wire 780 amplifier 778 subtracted in other amplifiers of the enhanced values of the signals on the wires 46 of the probes 202, 302, 402, 502 and 602. Thus the output signals on the eating definitely known, the probe 202 is in it. Therefore, the value of the signal on the wire 780 amplifier 778 specifies the reference zero or base point when the subtraction in other amplifiers.If the magnitude of the signal on the wire 380, 480, 580 or 680 is substantially different from the magnitude of the signal on the wire 280, for example, significantly less than the value on the wire 280, it shows that charred substance is not on the level of the relevant probes 302, 402, 502 or 602. On the other hand, if the magnitude of the signal on the wire 380, 480, 580 or 680 is close in value to the magnitude of the signal on the wire 280, it shows that charred substance has reached the desired probe and the signal can trigger indicators 390, 490, 590 or 690, respectively, which shows that charred substance is at least at the level of the corresponding probe 302, 402, 502 or 602. Indicators can be any lamp, each of which glows when exposed, and/or indicators may be analog or digital form or any other form of device, or to provide recording. If necessary, the device definition signal 392, 492, 592 and 692 may be installed at the outlet of each wire 380, 480, 580 and 680 to lock the trigger Velicina, for example, 40% or 50% of the value of the reference signal on conductor 86. Secured firing one indicator of 390, 490, 590 or 690, while on the corresponding wire 380, 480, 580 or 680 signal is above a specified value, it is possible to reduce the possibility of a false indication that the level of charred substance is at least at the level of the probe 302, 402, 502, or 602, when in fact it is not.The pressure inside hydrogenator 72 may be P kg/cm2(where R is any suitable value). In this case, a gas such as hydrogen or nitrogen, which is constantly supplied to the probe from the source 58 is in the gap 26 (Fig. 1) in each probe at a pressure (P+1,4) kg/cm2. A constant flow of gas through the probe has a cooling effect, especially on the cables 46, which reduces the possibility or softens the degree of reduction of the insulation resistance. 1. The measuring probe to determine whether the installation location of the probe electrically conductive material in pellet or liquid form, containing the first electrode and the second electrode surrounding the first electrode and placed with a certain gap with respect to the first electrode, which is held on the first cone so, what with the closure of the gap between the electrodes through the electrically conductive material, the electrical circuit through the probe is closed, and means for passing the gas between the first and second electrodes and an output at the first end of the second electrode, wherein the second electrode includes a tip, covering the first electrode, between the first and second electrodes posted by ceramic insulating material, the end of which is placed at the first end of the second electrode, and the ceramic insulating material is gas-permeable porous material through which the gas passes between the first and second electrodes and extend from the end.2. Probe under item 1, characterized in that the gas-permeable ceramic porous insulating material is heat resistant.3. Probe under item 1 or 2, characterized in that the first and second electrodes are made of heat resistant material.4. The probe according to any one of the preceding paragraphs, wherein the first electrode includes a tube through which gas enters the probe.5. Probe for p. 4, characterized in that the tube opens into the cavity of the probe, and this cavity is surrounded at least partially ceramic sairl tube, is electrically connected with the second electrode.7. Probe on p. 6, characterized in that the cable is heat resistant.8. The probe according to any one of the preceding paragraphs, characterized in that the first and second electrodes are made of stainless steel.9. Device for measuring the level of conductive material in pellet or liquid form containing multiple probes for level measurement, is connected to the circuit for measuring the level of material, wherein each of the multiple probes made according to any one of the preceding paragraphs and each of the probes to measure the level fixed at different levels within the container to electrically conductive material, the first and second electrodes of each of the probes to measure the level connected to the detector circuit of the measurement scheme to determine when the electrical circuit between the first and second electrodes of any of the probes by means of electrically conductive material, a gas source, connected to the means for supplying gas under pressure into the area between the first and second electrodes of each of the probes to measure the level and exit of gas from the end of the gas-permeable ceramic material problematum level, below which the level of the conductive material in the container does not drop during normal operation of the probe, this probe has a support of conducting material, made according to any one of p. 1 8 fixed in the container below the base level, so that during normal operation, the probe is always immersed in the electrically conductive material, and first and second reference electrodes of the probe are connected with the detector circuit for determining when the electrical circuit between the first and second reference electrodes of the probe by means of electrically conductive material, a gas source, connected to the means for supplying gas under pressure into the area between the first and second reference electrodes of the probe and the gas outlet end of the gas-permeable ceramic material of the reference probe, and each of the probes connected to the corresponding amplifier, the output signal of which is compared with a reference signal to the comparator for receiving amplifying the control signal that is a function of the difference between the output signal and a reference signal, and amplifying the control signal is supplied to each amplifier to change the gain.11. The device according to p. 10, characterized in that the Proa in the container does not rise during normal operation of the probes, there is a probe that supplies the reference signal errors made on any of the items 1 to 8 and secured in the container above the upper basic level so that during normal operation the probe applying the reference signal errors, never immersed in a conductive material, and first and second electrodes of the probe applying the reference error signal, is connected to the detector circuit for determining the moment of closing the gap between the first and second electrodes of the probe by means of electrically conductive material, a gas source connected to the means for supplying gas under pressure into the area between the first and second electrodes of the probe, feed the reference signal, error, and exit of gas from the end of the gas-permeable ceramic material of the probe, while the amplified output signal obtained from the probe applying the reference error signal, is used to change each output signal of each amplifier is connected to the probe for measuring the level of conductive material and the reference probe having a conductive material.12. The device according to p. 11, characterized in that the amplified output signal obtained from the probe reference error signal, is subtracted from each reinforced what I receiving a corresponding output signal from each amplifier, connected to the probes, measuring the level of conductive material.13. The device according to PP.9 to 12, characterized in that the probe is fixed in the part of the container, which is filled with granular material in the form of charred substances resulting from the processing of coal in the device hydrogenation.
FIELD: measuring engineering.
SUBSTANCE: device comprises fuel level indicator and rheostat pickup made of an analogue-digital converter with the balance input. The three-position switch is connected with the lever indicator. The device additionally has three resistive dividers, voltage stabilizer, and shunting resistor made of a 0.003-0.006-Om resistor. The rheostat level pickup is mounted inside the fuel tank vertically, and its linear horizontal size at this level is directly proportional to the area of the tank section in the horizontal plane at this level.
EFFECT: expanded functional capabilities.
FIELD: measuring engineering.
SUBSTANCE: method comprises pressing unit reinforced by electrodes with simultaneous forming of insulator between the electrodes. The space that is defined by surfaces of the electrodes is filled with casting plastic mass. The pressure tightness is provided by tightening the insulator with electrodes by means of a nut.
EFFECT: enhanced reliability.
FIELD: the invention refers to measuring technique and may be used for controlling bulk and liquid materials.
SUBSTANCE: the oscillating indicator of a level has a sensible element( a probe) 1 connected with an anchor 2, a driving arrangement 4 in the shape of a coil with a ferromagnetic core and also a sensor 5 of the displacements of the anchor, a drive-pulse generator 6 and an amplifier 7 and a relay block 9 successively connected. The amplifier is spanned with a regulated negative feedback fulfilled in the shape of a resistor 8. The sensor 5 of the displacements of the anchor may be fulfilled in the shape of a coil with a ferromagnetic core. At that the section of the anchor 2 between the coils is fulfilled out of non-magnetic material that prevents electromagnetic connection between the coils providing protection from high frequency oscillations in the system anchor-coil-amplifier.
EFFECT: allows to control the levels of the bulk and liquid materials being present in aggressive mediums, under pressure,( discharge)and at temperature till 200 degrees.
FIELD: instrument engineering.
SUBSTANCE: level meter sensor comprises hollow rigid base with the port in its bottom end, diaphragm, strain gage converter with box, flexible spacer arranged over periphery of the box, and tube whose one end is mounted pressure-tightly in the port of the support and the other end is connected to the space of the box. The diaphragm is made of a rigid material and mounted on the flexible spacer for permitting cooperation with the strain gage converter.
EFFECT: enhanced reliability and simplified structure.
FIELD: the invention refers to the field of instrument making and designed for control of the level of dielectric and current conducting liquids in hydraulic systems (fuel, freezing, accumulative etc) for example the level of oil or cooling agent in transport vehicles.
SUBSTANCE: the liquid level meter has a two-electrode capacitance sensor with an external 10 and interior 11 electrodes electrically connected with an electronic scheme having a stabilized source of power supply, an amplifier, a generator and a trigger. According to the first variant the capacitance sensor is fulfilled in the shape of a coaxial condenser "C". The interior electrode 11 of the sensor is fulfilled tubular and is mounted inside a fluoroplastic probing rod 12. The interior electrode 11 is connected to the input of a phase comparator which is additionally introduced in the scheme and whose output is connected with input of the trigger and the output of the last is provided with a line of delay and has two outputs - direct and inverse connected with a transistor key fulfilled with possibility of fulfillment of an operation "switched on" or "switched off". At that the electronic scheme is fulfilled on a digital integrated microchip. According to the second variant the interior electrode 11 of the coaxial condenser "C" is fulfilled tubular and is additionally provided with a protective shield 22. The shield 22 is fulfilled in the shape of a spiral spring out of bronze and electrically connected with the external electrode - the body 10 of the coaxial condenser "C".
EFFECT: increases sensitiveness and accuracy of measuring of the level of liquid.
6 cl, 4 dwg
FIELD: invention refers to control-measuring technique and is assigned for control and signaling about border of interface between mediums petroleum product-water in installations for purification water from petroleum products or watered petroleum products from water.
SUBSTANCE: sensor has flange, three electrodes with sleeves on their low ends filled with fresh water, moreover two of them are covered with dielectric insulation. Electrodes with sleeves are located inside tube of protective screen and are fastened in flange with aid of stuffing boxes-insulators. Screen in upper part has diaphragm ring with openings along circumference coinciding with openings in screen forming swinging compensator and is fastened to flange with aid of screws. Electrodes of sensor together with sleeves and electronic part form oscillating contour going in resonance at presence in space between electrodes of electric conductive medium (water) with following triggering of executive elements and at presence of water between electrodes of petroleum product resonance of contour stops.
EFFECT: increases reliability of work of sensor.
2 cl, 1 dwg
FIELD: physics, measurement.
SUBSTANCE: invention is related to the field of facilities for automation of different liquids level detection in industrial and household reservoirs, and also for detection of liquids availability and flow in pipelines. Method is based on application of two thermistors that have identical thermal characteristics, and includes heating of one of the thermistors by electric current and its cool-down due to heat transfer to environment, periodic measurement of voltage drop at thermistors, calculation of informative parameter, its comparison with threshold value and making decision on availability or unavailability of liquid at controlled level. At that one of thermistors is periodically heated by short pulses from power supply source. After heating is completed, ratio of non-heated and heated thermistors' voltages are repeatedly measured, and as informative parameter scaled time derivative is calculated by means of specified ratio measurement results array processing. Device for method implementation contains two thermoresistors, which are installed in sensitive element, connected to power supply source and which have temperature resistance coefficients (TRC) of the same sign and identical coefficient of heat emission in gas. Besides, it also contains analog-digital transducer and comparator, reference inlet of which is connected to source of reference signal, and outlet is connected with actuating device. Moreover, device is equipped with pulse switch and serially connected regulator of heating time and synchroniser, and also calculator of scaled derivative. For alarm on liquid flow availability, device is additionally equipped with the second comparator that is connected parallel to the first one, and the second actuating device.
EFFECT: higher efficiency of liquid level detection by increase of device actuation fast-action, reduction of power inputs and expansion of its application field.
13 cl, 3 dwg
FIELD: measuring technology.
SUBSTANCE: invention refers to a measuring device for determination of an amount d(V(z)) of conducting liquid of the conductivity LF by a capacity with vertically (z-direction) varied filling points. There is provided conductivity metre which among others has at least two electrodes extended in a z-direction. The capacitance parametres and/or the metres are ensured so that it/they can be described by means of at least one parametric function, fpi (V(z)) depending on V(z). At least one said parametric functions shall have exponential dependence on V(z). There is also described measuring element, and also method for determination of total amount of flowing liquid d (V).
EFFECT: simplified design of the device and method of measuring conductivity of the conducting liquid.
42 cl, 14 dwg
SUBSTANCE: method if based on measuring capacitance of a double-electrode capacitive liquid level sensor, which in turn in any sequence measures capacitance of the double-electrode capacitive liquid level sensor and capacitance of the same sensor is measured after connecting a capacitive sensor of dielectric properties to it, after which the level h from the upper end of the double-electrode capacitive liquid level sensor is calculated using the formula:
, where h is the level of the liquid in the reservior; CA is capacitance of the double-electrode capacitive liquid level sensor; CB is overall capacitance of the double-electrode capacitive liquid level sensor connected in parallel to the capacitive sensor of dielectric properties; A, B and D are structural parametres of the double-electrode capacitive liquid level sensor and capacitive sensor of dielectric properties. The device for measuring liquid level has a double-electrode capacitive liquid level sensor made in form of a coaxial capacitor, and two cylindrical electrodes. The lower end of the inner electrode of the double-electrode capacitive liquid level sensor is connected to one of the electrodes of the capacitive sensor of dielectric properties through the closing contact of a reed relay, and the lower end of the outer electrode of the double-electrode liquid level sensor is connected to the second electrode of the capacitive sensor of dielectric properties.
EFFECT: high accuracy of measuring the level of different liquids, as well as elimination of measurement errors caused by change in dielectric permittivity of the measured liquid.
2 cl, 1 dwg
SUBSTANCE: sensor for monitoring the level of a liquid has a housing and a printed-circuit board on which there is a substrate having one or two identical film resistors (thermistors) and contact pads (conductors). The printed-circuit board is in form of a plate, one short side of which is rigidly attached to the base of the housing and on the edge of the opposite free side there is a hole whose diameter is 2…4 times larger than the width of the substrate lying over the hole and made from thin heat-insulating material. Each film resistor (thermistor) is in 'point' form with dimensions in the range (0.15…0.5) mm • (0.5…0.5) mm and thickness not more than 0.0005 mm. The boundary surface between each film resistor (thermistor) and contact pads of the substrate (conductors) is in form of broken lines consisting of straight sections.
EFFECT: high mechanical strength of the structure.