RU187823U1 - Cable humidity and leakage sensor - Google Patents

Abstract

The utility model relates to measuring technique. The cable humidity and leakage sensor is made in the form of internal and external conductive plates, between which a dielectric strip of moisture-absorbing material is placed, and the conductive plates are made to be included in a serial circuit with a current source and a capacitance meter, the external conductive plate is made in the form of a grid of electrically conductive threads , the inner conductive lining is made in the form of a conductive metal core placed in an electrically conductive shell, and the dielectric The spherical gasket is made of polymer fibers, and an outer three-layer shell is introduced, covering the outer conductive lining, consisting of an internal dielectric capillary-porous layer and an external dielectric capillary-porous layer, between which a conductive grounded layer in the form of a network of electrically conductive threads is placed, with the following characteristics : diameter of conductive filaments 0.01-0.3 mm; coefficient of surface density 50-95%. The technical result is to increase operational reliability, including mechanical reliability, electromagnetic immunity and safety of use. 1 ill.

Description

The utility model relates to measuring technique and is intended for continuous monitoring of air humidity and leaks at its locations.

A device for measuring air humidity [RU 2184369 G01N 25/56, G01N 27/22, G21C 17/00, 06/27/2002], comprising a capacitive humidity sensor and a resistive temperature sensor, an alternating voltage amplifier, an alternating voltage level meter, a functional unit, an alternating voltage generator, an electronic converter of the resistance of the resistive sensor into voltage (current), a registrar, the output of the generator being connected by a long line to one of the contacts of the capacitive sensor, the output of the voltage amplifier is connected to the input of the level meter voltage, the output of which is connected to one of the inputs of the function block, the second input of which is connected to the output of the resistance transducer into an electrical signal (current, voltage), to the input of which a resistive temperature sensor is connected using a long line, and the output of the function block is connected to the registrar, characterized in that the primary winding of the matching transformer is connected to the second contact of the capacitive sensor, the second end of which is connected by a long line to the alternating voltage generator And to the secondary winding of the transformer is connected to the signal line characteristic impedance, the second end of which is connected to the input terminals of the voltage amplifier, wherein the modulus of the complex impedance of the primary winding of the transformer is connected to the signal line must be 100-200 times smaller than the modulus integrated capacitive sensor resistance.

The disadvantages of this device is the relatively low sensitivity, high inertness and structural complexity.

A humidity sensor is also known [RU 2263936, G01W 1/11, G01N 25/56, 10.11.2005], comprising an electrical insulating base, an electrical insulating substrate with a moisture sensitive coating based on gelatin on its surface, the outer layer of which is roughened, two patch electrodes, a contact the surface of which is made oxidized and flat and is in contact with the moisture-sensitive layer, and a measuring device connected to the terminals of the overhead electrodes, as well as two clamping nodes, each of which is designed to create a constant detecting respective applicator on the working surface of moisture-sensitive coatings.

The disadvantage of this device is the relatively low accuracy caused by the non-linear relationship between the electrical signal and the humidity level.

In addition to the above, a humidity sensor is known [RU 2365908, G01N 27/12, 08/27/2009] having an insulating dielectric substrate made of borate-bismuth glass, a moisture-sensitive layer, which is obtained by special etching of the substrate, as well as two electrical contacts located in the recesses on the surface of the substrate, in this case, the measurements are carried out on alternating current with a frequency of 1 kHz using an immitance meter.

The disadvantage of this device is its relatively high complexity and high cost.

In addition to the above, also known humidity sensor [RU 2167414 G01N 27/22, 05/20/2001], including conductive plates and a moisture-absorbing layer made of sheet filter material impregnated with alkali metal carbonates, and the conductive plates are placed in a sealed dielectric cover.

The disadvantage of this capacitive humidity sensor is its relatively low sensitivity.

A humidity sensor is also known [RU 2167414, U1, G01N 27/00, 06/10/2015], including a moisture-absorbing layer impregnated with alkali metal salts and conductive plates, while the conductive plates are made in the form of two metal grids, between which there is a moisture-absorbing layer, made of thin paper impregnated with sodium chloride, metal grids are fastened around the perimeter and connected in series with a current source and a measuring device.

The specific features of the known humidity sensor is that the moisture-absorbing layer is made of tissue paper, which is made of porous metal mesh made of brass, glued around the perimeter with an adhesive layer and made in the form of rectangles 10 × 10 mm ² in size with each mesh size 1 × 1 mm ² , while a multimeter or a galvanometer is used as a measuring device.

The disadvantage of this technical solution is its relatively low strength and operational reliability, due to the fact that the moisture-absorbing layer is made of thin paper, in particular tissue paper, which is made porous, and also that the conductive plates between which the moisture-absorbing layer is located are made in the form two metal grids.

Closest to the claimed is a device [RU 179730, U1, G01N 27/22, 05/23/2018], made in the form of internal and external conductive plates, between which is placed a dielectric strip of moisture-absorbing material, moreover, conductive plates made with the possibility of inclusion in series a circuit with a current source and a capacitance meter, and the external conductive lining is made in the form of a grid of electrically conductive threads, while the internal conductive lining is made in the form of a conductive metal core, placed in an electrically conductive shell, and the dielectric strip is made of woven from polymer fibers.

The disadvantage of the closest technical solution is the relatively low operational reliability and safety of use. This is due, in particular, to the fact that the grid of electrically conductive threads, which is used for the external conductive lining, is subject to abrasion and integrity damage due to external mechanical influences. In addition, the relatively low safety of the application is a significant drawback, since the outer lining is conductive, which limits the scope of the sensor in places where electrical contact with surfaces on which the sensor is located, for example, inside electronic equipment housings, etc., is not allowed. Another important drawback is the external conductive lining, which is open to the influence of electromagnetic fields of electronic equipment, which, as a result, causes interference in the operation of the device and reduces its operational reliability.

The objective of this utility model is to create a highly sensitive cable humidity and leakage sensor with higher operational reliability, including mechanical reliability, electromagnetic immunity, and application safety.

The required technical result is to increase operational reliability, including mechanical reliability, electromagnetic immunity and safety of use.

The problem is solved, and the required technical result is achieved by the fact that, in a device made in the form of internal and external conductive plates, between which a dielectric strip of moisture-absorbing material is placed, moreover, the conductive plates are made with the possibility of inclusion in a serial circuit with a current source and meter containers, the external conductive lining is made in the form of a grid of electrically conductive threads, the internal conductive lining is made in the form of a conductive metal of a vein placed in an electrically conductive sheath, and the dielectric spacer is made of polymer fibers, according to a utility model, an outer three-layer sheath is introduced, covering the outer conductive sheath, consisting of an internal dielectric capillary-porous layer and an external dielectric capillary-porous layer, between which a conductive grounded layer in the form of a grid of electrically conductive filaments, with the following characteristics:

diameter of electrically conductive threads - 0.01-0.3 mm;

surface density coefficient - 50-95%

The drawing shows the design of a cable humidity and leakage sensor together with a circuit containing a current source and a capacitance meter, grounding and external influence in the form of moisture drops.

In the drawing are indicated:

1 - internal conductive lining, made in the form of a conductive metal core;

2 - conductive sheath of a conductive metal core;

3 - a dielectric strip made of woven from polymer fibers;

4 - external conductive lining, made in the form of a grid of electrically conductive threads;

5 - inner dielectric capillary-porous layer of the outer three-layer shell;

6 - conductive grounded layer of the outer three-layer shell, made in the form of a grid of electrically conductive threads;

7 - external dielectric capillary-porous layer of the outer three-layer shell;

8 - drops of moisture (water or other electrically conductive liquid);

9 is a circuit containing a current source and a capacitance meter;

10 - grounding of the conductive plate-screen.

The moisture and leakage cable sensor is made in the form of an inner 1 and an outer 4 conductive plates, between which a dielectric strip 3 of a moisture-absorbing material is placed.

In the cable humidity and leakage sensor, the conductive plates 1 and 4 are configured to be connected in series circuit 9 with a current source and a capacitance meter, while the external conductive plate 4 is made in the form of a network of conductive threads, the internal conductive plate 1 is made in the form of a conductive metal veins placed in an electrically conductive shell 2, and the dielectric strip 3 is made of woven from polymer fibers.

In addition, an outer three-layer shell is introduced, covering the outer conductive plate 4, consisting of an internal dielectric capillary-porous layer 5 and an external dielectric capillary-porous layer 7, between which a conductive grounded layer 6 is placed in the form of a network of electrically conductive threads.

The dielectric strip 3 and the capillary porous layers 5,7 can be made of fiberglass or polymer fibers.

The proposed cable humidity and leakage sensor is used as follows.

The design of the cable humidity and leakage sensor is an essentially long cylindrical capacitor. The role of the capacitor plates in this capacitor is performed by the inner surface of the outer conductive plate 4, made in the form of a grid of electrically conductive metal wires or carbon filaments, and the outer side of the electrically conductive shell 2 for the conductive metal core 1. The role of the dielectric strip inside this capacitor is performed by the dielectric strip 3 of the moisture absorbing material woven from fiberglass or polymer fibers. Owing to its design and manufacturing technology, such a “cable-capacitor” can have almost any length, has high strength and operational reliability, in particular, it easily bends, is resistant to external mechanical stresses, vibrations, etc.

To protect against external mechanical influences, to ensure safety when used in places where electrical contact with the surfaces on which the device is not allowed, and to provide electromagnetic protection, it contains an external three-layer shell covering the external conductive lining, consisting of an internal dielectric capillary porous layer 5 and an external dielectric capillary-porous layer 7, between which a conductive grounded layer 6 is placed in the form of an electric circuit leading threads, with the following characteristics, the diameter of the conductive threads is 0.01-0.3 mm, the coefficient of surface density is 50-95%.

If such a cable humidity and leakage sensor is placed in humid air, then the droplets 8 of water or other electrically conductive liquid located there interact with it and, penetrating through the external dielectric capillary-porous layer 7, the conductive grounded layer 6 in the form of a grid of electrically conductive filaments, the internal dielectric capillary porous layer 5, the outer conductive plate 4, made in the form of a grid of electrically conductive metal wires or carbon filaments, is absorbed (sorbed) into the dielectric minutes liner 3 of absorbent material woven from glass fibers or polymer fibers change in its dielectric constant. This leads to a change in the measured electrical capacitance of such a cable humidity and leakage sensor.

The dependence of the capacitance C on the ambient humidity f _a and the basic geometric parameters of the proposed cable sensor is described by the expression

where: S is the area of the outer surface;

1 - the thickness of the dielectric strip 3 of a moisture-absorbing material;

8 - dielectric constant of water;

k1, k2 are constant coefficients.

From the above ratio it follows that a change in environmental humidity leads to a proportional change in the measured capacitance.

With leaks, which manifests itself as a sharp change in the humidity of the environment, the change in capacitance will be spasmodic, which can be taken into account when taking measurements from the capacitance meter.

Due to the long construction of the capacitor cable, its external sensory area and effective sensory volume capturing water molecules are practically unlimited. This circumstance allows, accordingly, to unlimitedly expand the volumes of the space controlled by them without reducing the accuracy of measurements.

Thus, in the proposed design of the humidity sensor, the required technical result is achieved, which consists in increasing operational reliability, including mechanical reliability, electromagnetic immunity and safety of use.

Claims (2)

A humidity and leakage cable sensor made in the form of internal and external conductive plates, between which a dielectric strip of moisture-absorbing material is placed, wherein the conductive plates are capable of being connected to a series circuit with a current source and a capacitance meter, and the external conductive plate is made in the form of a network of electrically conductive threads, the inner conductive lining is made in the form of a conductive metal core placed in an electrically conductive shell, and die the electrical wiring is made of woven polymer fibers, characterized in that an external three-layer shell is introduced, covering the external conductive lining, consisting of an internal dielectric capillary-porous layer and an external dielectric capillary-porous layer, between which a conductive grounded layer is placed in the form of a network of electrically conductive threads, with following characteristics: diameter of conductive threads 0.01-0.3 mm surface density coefficient 50-95%.

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