CN2074913U - Digital soil conductivity testing instrument - Google Patents

Abstract

Disclosed is a digital soil conductivity testing instrument which is composed of a host machine, conductive electrical cables and measuring electrodes. A plug-in type probe electrode that is composed of a guide cone, polar rings, an insulation support, electrode posts, a junction box and a leading wire socket is developed. The utility model is multi-purpose for directly measuring the conductivity of field soil and liquids, such as laboratory solution, pure water, etc. The utility model can be inserted into soil and measure the conductance values of soil layers with different depths directly without sampling and stirring the soil body and can achieve initial state and in situ measurements at a long distance.

Description

Digital soil conductivity testing instrument

The utility model relates to a kind of laboratory and testing tool is led in the field test electricity consumption.

Field to soil conductivity is directly measured, and domestic now do not have an instrumentation, and the external four electrode methods that adopt are measured more.Four electrode method be since the seventies more external scholars with the method for using in the geophysical survey, draw to borrow and develop on the soil conductivity mensuration, when being the research soil conductivity, its advantage do not take a sample, do not stir the soil body, can survey at need and carry out ortho states---original position Continuous Observation in the soil, measured value and soil extraction electric conductivity value have correlativity preferably.

Four electrode method is a DC-method.The DC-method electrode polarization is serious, generally is not used in two determination of electrode.Because the electric current line is non-enclosed type between the four electrode method electrode, if when being used for experimental determination small size pure water and solution example, because the container interface influence, error is bigger and inapplicable, makes the usable range of this method be subjected to significant limitation.

The conductance for alternating current instrument that present domestic use is more because the influence of electrode shape and electrode conductive wire line capacitance can only be confined to closely measure in the laboratory and use, can't be used for remote ortho states---the in-site detecting that the field soil electricity is led.

The purpose of this utility model be to develop a kind of connect current electrode or electrode special after, the conductance measurement that can be used for laboratory small size pure water and solution example, can be used for the field soil electricity again and lead ortho states---the precision of original position multi-site determination is higher, stable performance, convenient reading, volume is little, and is in light weight, portable multi-usage galvanic size tester.

The technical solution adopted in the utility model is to exchange determination method, design, employing insertion probe electrode, nothing appearance conducting cable and fully integratedization circuit.Its concrete technical measures are: develop an insertion probe electrode of being made up of leading cone, polar ring, insulation support, electrode column, terminal box and lead socket; The effect of leading cone is the pressure that improves probe, makes it insert in the soil easily; Polar ring is a potential electrode, and each conductance cell constitutes by two polar rings, and is middle by the insulation support and connection; Insulation support and electrode column by acid and alkali-resistance, ageing resistance is strong, resistance is big, moisture absorption is little, not only tough but also hard tubular material is made, the size of probe internal diameter goes between and is as the criterion not influence overall construction intensity and can pass polar ring; The effect of terminal box and lead socket is to be connected the polar ring lead-in wire and not have the appearance conducting cable.

Technical measures that do not have to hold conducting cable are each heart yearn to be carried out individually shielded, and like this, screen layer is after ground connection, and the distributed capacitance between its heart yearn is zero substantially, and do not change with the variation of cable length.It can overcome the influence of lead capacitance, prolongs the distance between sensor and control and the measuring equipment, is convenient to operation.Can also improve the precision and the reliability of measurement.

The electricity principle is please referring to accompanying drawing 3, at A ₁Output terminal be connected to D ₆, at D ₆With T ₅Between and be connected with R ₁₀, C ₃, integrated transporting discharging A ₁And A ₂Constitute the high precision sine-wave generator, and by integrated transporting discharging A ₃Carry out providing conductance cell to measure voltage V after the power amplification ₁The conductance cell that provides of the circuit stability of measuring voltage and frequency can realize 0.1% precision at an easy rate thus.Change capacitor C according to measuring needs ₄, C ₇With regulator potentiometer W ₁, the conductance cell that can obtain different frequency and voltage is measured AC power source of sine wave, and when its output voltage was the 1V left and right sides, its temperature coefficient approached zero.Integrated transporting discharging A ₄With V ₁The bucking voltage V that eliminates electrode and measure the remaining distributed capacitance influence of cable is provided after anti-phase ₂Capacitor C ₉With R ₂₂Parallel connection is to bucking voltage V ₂Carry out phase compensation, to compensate distributed capacitance to measuring voltage V ₁Phase shift affects.Capacitor C ₁₅With R ₃₂Parallel connection is to current rectifying and wave filtering circuit A ₆Carry out frequency compensation, make it when measuring same resistance, obtain identical electric conductivity value with different frequency.

Advantage of the present utility model is: 1. electrode is difficult for polarization and the big characteristics of versatility both can be used for the laboratory when having kept AC method and surveying electricity and lead, and can be used for open-air the detection again; 2. the insertion probe electrode has single electrode and compound electrode multiple, can select different electrodes for use according to different test requests; 3. instrument is that liquid crystal digital shows that volume is little, in light weight, power consumption is few, good stability, is easy to carry with dry cell power supply.

Description of drawings:

Fig. 1 is an insertion probe electrode structure synoptic diagram; Fig. 2 does not have the conducting cable of appearance structural representation; Fig. 3 is the instrument host circuit theory diagrams.Wherein: a is a monoelectrode sonde; B is a compound electrode probe of measuring the multiple degree of depth; 1, leading cone; 2, polar ring; 3, insulation is supported; 4, electrode column; 5, terminal box; 6, measure cable gang socket; 7, the electrode retaining collar lead-in wire; 8, copper core; 9, heart yearn polyvinyl chloride insulation layer; 10, the copper wire woven shield; 11, the polyvinyl chloride insulation sheath.

In the circuit theory diagrams: A ₁～A ₄Be the low maladjustment voltage amplifier; A ₅Be the high input impedance amplifier; R ₂₃～R ₂₇For precision less than 0.1% precision resistance.

Embodiment:

Leading cone, the polar ring of probe electrode are made of stainless steel material, and when electrode was had relatively high expectations, polar ring can adopt alloy platinum material to make.Insulation support, electrode column, terminal box adopt nylon material car system or the injection mo(u)lding all can (present embodiment forms for car system).

The polar ring lead-in wire is single-core shielding line, and an end is welded on the electrode retaining collar inboard, and the other end is treated to be welded on the socket when assembling at last.

Each seam crossing of probe will be used epoxy encapsulation.

Do not have to hold conducting cable owing to has on the market and do not sell, can oneself with two no sheath single-core shielding lines also together after, put the polyvinyl chloride insulation sheath again.Can be customized during batch process to producer.

Host shell both can be made of the engineering plastics mold pressing, and also the available metal material is made through plumber's processes.The plastic casing inwall need paste with aluminium foil and shield, and metal shell should be noted and the earth insulation (present embodiment plastic casing).

The first components and parts that are welded in printed board of host circuit board, the lead-in wire that is welded on base plate again carries out general assembly and debugging at last.

Claims (2)

1, a kind of by instrument host, digital soil conductivity instrument that conducting cable and potential electrode constituted, it is characterized in that: A in host circuit ₁Output terminal is connected to D ₆Negative pole, at D ₆Positive pole to T ₅Between be parallel with R ₁₀, C ₃, R ₁₀, C ₃Other end ground connection; R ₂₂With capacitor C ₉Parallel connection, its two 1 ends and R ₂₀, A ₄Inverting input connects, the other end and A ₄Output terminal, C ₁₂, C ₁₃Connect; R ₃₂Be parallel with capacitor C ₁₅, its two 1 ends and R ₃₃, D ₁₀Negative pole connects, the other end and R ₃₀, D ₉Anodal, A ₆Inverting input connects; Two heart yearns of conducting cable have carried out individually shielded separately; Measuring electrode is made of leading cone, polar ring, insulation support, electrode column, terminal box and lead socket.

2, conductivity meter according to claim 1 is characterized in that measuring electrode and is made up of two or more even number polar rings.

Images