CN102023259A - Method for improving measuring accuracy and correcting measuring range of ground resistor - Google Patents

Abstract

The invention relates to a ground resistance measuring method, in particular to a method for improving the measuring accuracy and measuring range of a ground resistor. The method includes the following steps: 1, compensation voltage is calculated; and 2, ground resistance is calculated by combining the compensation voltage. According to the invention, measurement parameters can be effectively compensated under the condition that probe resistance and auxiliary resistance are varied widely, thus improving the measuring accuracy and expanding the measuring range.

Description

A kind of modification method that improves grounding resistance measurement precision and scope

Technical field

The present invention relates to a kind of measuring method of stake resistance, especially a kind of modification method that improves grounding resistance measurement precision and measurement range.

Background technology

The overwhelming majority's earth resistance tester on the market, the grounding resistance measurement scope is in 0-10 kilohm, during measurement of Grounding Resistance that main cause is three-way (four-wire system), stake resistance, probe resistance influences each other between three resistance of auxiliary resistance, and due to the amplifier nonlinearity, the algorithm that this patent relates to is according to the substantive test data.Find an effective compensation formula.Can be at probe resistance (Rs), auxiliary resistance (R _h) under the situation of wide variation, effective compensating measure parameter.Reach the raising measuring accuracy, enlarge stake resistance scope to 300 kilohm.Fig. 1 is the measurement of Grounding Resistance schematic diagram, and G is a ground-electrode to be measured, and the equivalent resistance between ground-electrode and the earth is R _G, P is a probe electrode, and the equivalent resistance between probe electrode and the earth is Rs, and C is an auxiliary electrode, and the equivalent resistance between auxiliary electrode and the earth is R _h, E is an AC power, electric current flows between C and G, can produce an alternating voltage between G and P, by measuring voltage U between the electric current I passed through between C and the G and P and the G _G, can try to achieve stake resistance R _G

Find that in test current value is basically only with R _GWith R _hRelevant, Rs influences seldom its, but voltage U _GMeasuring accuracy, be subjected to R _hVery big with the Rs influence, if do not try every possible means this influence is eliminated, directly have influence on the full test range of instrument, and measuring accuracy.

Summary of the invention

The invention provides a kind of modification method that improves grounding resistance measurement precision and scope.

To achieve these goals, the present invention adopts following technical scheme:

Comprise the steps:

1, calculates bucking voltage;

2, calculate stake resistance in conjunction with bucking voltage.

Preferably, described calculating bucking voltage step comprises step:

11. measure R _GThe series value of two resistance of+Rs;

12. measure R _G+ R _hThe series value of two resistance;

13. measure R _GEstimated value R _G';

14. can calculate Rs and R by 3 values in front _hEstimated value;

15, by Rs and R _hEstimated value calculate the bucking voltage value.

Preferably, described step 14 is specially by formula U _Rscomp=(k1+k2*R _G) * R _SBe compensated voltage, wherein k1 is a constant coefficient, only with supply voltage V _eRelevant.K2 is a slope coefficient, it and R _G+ R _hTotal resistance value relevant.

Preferably, described k1=t1+t2*V _e, $\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="H2009101926317E00012.png,H2009101926317E00021.png"\; state="\{\{state\}\}">k</figure-callout>}2=\frac{1}{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="H2009101926317E00021.png"\; state="\{\{state\}\}">t</figure-callout>}3+\mathrm{<figure-callout\; id="4"\; label="t"\; filenames="H2009101926317E00021.png"\; state="\{\{state\}\}">t</figure-callout>}4*(R_G+R_h)}$ T1-t4 is a constant in, and is relevant with circuit design parameter, can be approximately constant likes); V _eWith (R _G+ Rh) directly measure by circuit.

Preferably, described in conjunction with bucking voltage calculate stake resistance comprise do not do earlier voltage compensation measure an approximate value, substitution formula U again _Rscomp=(k1+k2*R _G) * R _SIn, calculate bucking voltage, pass through formula at last $R_G=\frac{U_G+U_{\mathrm{Rscomp}}}{I}$ Try to achieve accurate relatively R _GResistance.

Owing to adopted said method, the present invention effectively compensates measurement parameter under the situation of probe resistance, auxiliary resistance wide variation, thereby reaches the raising measuring accuracy, enlarges measurement range.

Description of drawings

Fig. 1 is the syndeton synoptic diagram that trilinear method is surveyed stake resistance;

Fig. 2 is the process flow diagram of the embodiment of the invention;

Fig. 3 is that the embodiment of the invention is calculated the bucking voltage flow chart of steps;

Fig. 4 is a comparative effectiveness form before and after the embodiment of the invention compensation.

The object of the invention, function and advantage will be in conjunction with the embodiments, are described further with reference to accompanying drawing.

Embodiment

Fig. 1 is the measurement of Grounding Resistance schematic diagram, and G is a ground-electrode to be measured, and P is a probe electrode, C is an auxiliary electrode, and E is an AC power, and electric current flows between C and G, between G and P, can produce an alternating voltage, by measuring voltage U between the electric current I passed through between C and the G and P and the G _G

As shown in Figure 2, the modification method of present embodiment comprises step:

1, calculates bucking voltage;

2, calculate stake resistance in conjunction with bucking voltage.

Wherein, as shown in Figure 3, described calculating bucking voltage step comprises step:

11. measure R _GThe series value of two resistance of+Rs;

12. measure R _G+ R _hThe series value of two resistance;

13. measure R _GEstimated value R _G';

14. can calculate Rs and R by 3 values in front _hEstimated value;

15, by Rs and R _hEstimated value calculate the bucking voltage value.

Concrete measurements and calculations method is as follows: the stake resistance R that at first obtains G by following formula _G:

$R_G=\frac{U_G}{I}---\left(1\right)$

Rs is to U _GIt is linear that the influence of measuring is essentially.Rs is big more, power supply E voltage V _eBig more, U _GLess than normal more, can be as follows with formulae express:

U _Rscomp＝(k1+k2*R _G)*R _S (2)

Wherein k1 is a constant coefficient in (2) formula, only with supply voltage V _eRelevant.K2 is a slope coefficient, it and R _G+ R _hTotal resistance value relevant.Concrete formula is as follows:

k1＝t1+t2*V _e (3)

$k2=\frac{1}{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="H2009101926317E00021.png"\; state="\{\{state\}\}">t</figure-callout>}3+\mathrm{<figure-callout\; id="4"\; label="t"\; filenames="H2009101926317E00021.png"\; state="\{\{state\}\}">t</figure-callout>}4*(R_G+R_h)}---\left(4\right)$

T1-t4 is a constant in the formula (3), (4), and is relevant with circuit design parameter, can be approximately constant; V _eWith (R _G+ Rh) can directly measure by circuit; Because R in the formula (2) _GBe parameter to be measured, can be by the method that returns, do not do earlier voltage compensation measure an approximate value R _G', in the substitution formula (2), calculate bucking voltage again, try to achieve accurate relatively R by following formula (5) at last _GResistance.

$R_G=\frac{U_G+U_{\mathrm{Rscomp}}}{I}---\left(5\right)$

U wherein _GThe magnitude of voltage that directly measures for circuit.I is the current value that circuit directly measures.

Compensate the front and back comparative effectiveness as shown in Figure 4, as seen from Figure 4, after over-compensation, R _GPrecision is at Rs and R _hIn the wide variation scope.Can keep more higher precision.

The above only is the preferred embodiments of the present invention; be not so limit claim of the present invention; every equivalent structure or equivalent flow process conversion that utilizes instructions of the present invention and accompanying drawing content to be done; or directly or indirectly be used in other relevant technical fields, all in like manner be included in the scope of patent protection of the present invention.

Claims (5)

1. a modification method that improves grounding resistance measurement precision and measurement range is characterized in that, comprises the steps:

1, calculates bucking voltage;

2, calculate stake resistance in conjunction with bucking voltage.

2. the modification method of raising grounding resistance measurement precision as claimed in claim 1 and measurement range is characterized in that, described step 1 further comprises step:

11. measure R _GThe series value of two resistance of+Rs;

12. measure R _G+ R _hThe series value of two resistance;

13. measure R _GEstimated value R _G';

14. can calculate Rs and R by 3 values in front _hEstimated value;

15, by Rs and R _hEstimated value calculate the bucking voltage value.

3. the modification method of raising grounding resistance measurement precision as claimed in claim 2 and measurement range is characterized in that: described calculating bucking voltage step is specially by formula U _Rscomp=(k1+k2*R _G) * R _SBe compensated voltage, wherein k1 is a constant coefficient, only with supply voltage V _eRelevant.K2 is a slope coefficient, it and R _G+ R _hTotal resistance value relevant.

4. the modification method of raising grounding resistance measurement precision as claimed in claim 3 and measurement range is characterized in that: described k1=t1+t2*V _e, $k2=\frac{1}{t3+t4*(R_G+R_h)}$ T1-t4 is a constant in, and is relevant with circuit design parameter, can be approximately constant likes); V _eWith (R _G+ Rh) directly measure by circuit.

5. the modification method of raising grounding resistance measurement precision as claimed in claim 4 and measurement range is characterized in that: described in conjunction with bucking voltage calculate stake resistance comprise do not do earlier voltage compensation measure an approximate value, substitution formula U again _Rscomp=(k1+k2*R _G) * R _SIn, calculate bucking voltage, pass through formula at last $R_G=\frac{R_G+U_{\mathrm{Rscomp}}}{I}$ Try to achieve accurate relatively R _GResistance.

Images