CN101217594A - A test method of insulation resistance and capacitance on telephone lines - Google Patents

Abstract

The invention provides a test method of insulation resistance and capacitance on a circuitry, comprising the steps that: a line A of two circuitries on a telephone circuitry is short connected to the ground, and then a constant-current source is used for exciting a line B, and a first common insulation resistance value and a first common capacitance value between the line A and the line B as well as between the line B and the ground are tested; the line B of the two circuitries of the telephone circuitry is short connected to the ground, and then the constant-current source is used for exciting the line A, a second common insulation resistance value and a second common capacitance value between the line B and the line A as well as the line A to the ground are tested; the line A is short connected with the line B, and then the constant-current source is used for exciting the short connected line A and line B, and a third common insulation resistance value and a third common capacitance of the short connected line A and line B to the ground are tested; the line A and the line B are hung in the air and then a fourth common insulation resistance value between the line B and the line A, the line A to the ground as well as the line B to the ground is tested; the capacitance value between the line A and the line B, the capacitance value between the line A to the ground, and the capacitance between the line B to the ground are calculated.

Description

The method of testing of insulation resistance and electric capacity on the telephone line

Technical field

The present invention relates to the measurement of resistance and electric capacity in the telephone subscriber line test, comprise to the electric capacity between two outside lines on the telephone line and resistance and two outside lines separately over the ground resistance and electric capacity measure.

Background technology

In the maintenance work of present communication network, the maintenance of user outline has accounted for very big ratio, so a route survey system accurately and efficiently is provided, the efficient that improves lineman's fault location has great importance.

As everyone knows, modal kind comprises in the communication line fault: ground vapour, swinging cross, broken string, defective insulation or the like.Present most route survey system carries out the test of 12 parameters of outside line earlier, comprises between A, the B line, and the A line over the ground direct voltage, alternating voltage, insulation resistance of B line, also has electric capacity over the ground; And then these 12 parameters are carried out analysis-by-synthesis provide fault judgement qualitatively.

This paper mainly discusses the method for testing of insulation resistance and electric capacity on the circuit, and this also is two big class parameters of difficult test in 12 parameters of outside line.Existing method of testing mainly contains two classes: the first kind is based on the test of stable state, that is to say to wait for that test circuit enters stable state and just can calculate, and as application number 97108938.8 Chinese patent application.These class methods often need the measurement of resistance and electric capacity is separated, to get rid of the influence of electric capacity during measuring resistance, to get rid of the influence of resistance when measuring electric capacity, but user outline resistance and electric capacity often is simultaneous, can't get rid of resistance simply and go single survey electric capacity or get rid of electric capacity and remove single measuring resistance, a shortcoming that causes this method be measure accurate inadequately.In addition, owing to need circuit to reach constant-current source excitation stable state, so the testing time that this method needs is long.Another kind of method does not need circuit to reach constant-current source excitation stable state, do not need the test of resistance and electric capacity is separated yet, and as application number 00114864.8 Chinese patent application.The test speed of this method is very fast, but owing to be based on and differentiate, the noise on the circuit often produces bigger influence to result of calculation, causes resistance and electric capacity to calculate inaccuracy.

Summary of the invention

The present invention overcomes problem and the defective that precision, the stability of the insulation resistance of the line circuit that exists in the prior art and electric capacity is not enough and can not test the outside line backward resistance, and the method for testing of insulation resistance and electric capacity on a kind of circuit is provided.

This method of testing may further comprise the steps: with the short circuit over the ground of the A line in two circuits on the telephone line, with constant-current source the B line is encouraged then, measure the response voltage on the B line, by the time constant-current source excitation stable state, measure the steady state voltage on the B line, and measure between A line and B line and first common insulating resistance value and the first common capacitance of B line between over the ground; With the short circuit over the ground of the B line in two circuits on the telephone line, with constant-current source the A line is encouraged then, measure the response voltage on the A line, by the time constant-current source excitation stable state, measure the steady state voltage on the A line, and measure between B line and A line and second common insulating resistance value and the second common capacitance of A line between over the ground; With A line and B line short circuit, then with A line and the B line excitation of constant-current source after to short circuit, by the time constant-current source excitation stable state is measured A line behind the short circuit and the response voltage on the B line, and measures A line and B line the 3rd common insulating resistance value and the 3rd common capacitance over the ground behind the short circuit; A line and B line is all unsettled, then with constant-current source to A line excitation, the stable state of constant-current source excitation is by the time measured the response voltage on the A line, and measure between B line and A line, the A line over the ground between and the four common insulating resistance value of B line between over the ground; And calculate A line and B wire insulation resistance value, B line and A wire insulation resistance value, A line insulating resistance value and the insulating resistance value of B line between over the ground between over the ground, and calculate A line and B line capacitance value, A line capacitance and the capacitance of B line between over the ground between over the ground according to the first common capacitance, the second common capacitance, the described the 3rd common capacitance according to the first common insulating resistance value, the second common insulating resistance value, the 3rd common insulating resistance value and the 4th common insulating resistance value.

Wherein, A line on telephone line in two circuits over the ground short circuit, with the described B line in two circuits on the telephone line over the ground short circuit, with described A line and described B line short circuit or with described A line and described B line all unsettled after, further comprising the steps of: to described two line discharges.

Compare in insulating resistance value, A line and B line capacitance value between over the ground of insulating resistance value between over the ground of the A line that calculates and B wire insulation resistance value, B line and A wire insulation resistance value, A line, B line, A line capacitance and the capacitance and the corresponding standard value of B line between over the ground between over the ground, and determine whether to exist fault according to comparative result.

According to method of testing of the present invention, A line and B wire insulation resistance value, B line and A wire insulation resistance value, A line insulating resistance value and the insulating resistance value of B line between over the ground between over the ground calculates by following formula:

$\left\{\begin{array}{c}G1=\mathrm{Gba}+\mathrm{Gag}\\ G2=\mathrm{Gab}+\mathrm{Gbg}\\ G3=\mathrm{Gag}+\mathrm{Gbg}\\ G4=\frac{1}{\frac{1}{\mathrm{Gba}}+\frac{1}{\mathrm{Gbg}}}+\mathrm{Gag}\end{array}\right.$

Wherein, G1=1/R1, G2=1/R2, G3=1/R3, G4=1/R4, Gab=1/Rab, Gba=1/Rba, Gag=1/Rag, Gbg=1/Rbg, R1 be the first common insulating resistance value, R2 be the second common insulating resistance value, R3 be the 3rd common insulating resistance value, R4 be the 4th common insulating resistance value, Rab be A line and B wire insulation resistance value, Rba be B line and A wire insulation resistance value, Rag be the A line over the ground between insulating resistance value and Rbg be the B line over the ground between insulating resistance value.

According to method of testing of the present invention, it is characterized in that A line and B line capacitance value, A line capacitance and the capacitance of B line between over the ground between over the ground calculates by following formula:

$\left\{\begin{array}{c}C1=\mathrm{Cab}+\mathrm{Cag}\\ C2=\mathrm{Cab}+\mathrm{Cbg}\\ C3=\mathrm{Cag}+\mathrm{Cbg}\end{array}\right.$

Wherein, C1 be the first common capacitance, C2 be the second common capacitance, C3 be the 3rd common capacitance, Cab be A line and B line capacitance value, Cag be the A line over the ground between capacitance, Cbg be B line direct-to-ground capacitance value.

The time that constant-current source excitation arrives stable state is by the parallel resistance value of the common insulating resistance value of circuit in the resistance value at the two ends that are connected in parallel on constant-current source and each step and common capacitance decision.

Other features and advantages of the present invention will be set forth in the following description, and, partly from specification, become apparent, perhaps understand by implementing the present invention.Purpose of the present invention and other advantages can realize and obtain by specifically noted structure in the specification of being write, claims and accompanying drawing.

Description of drawings

Accompanying drawing is used to provide further understanding of the present invention, and constitutes the part of specification, is used from explanation the present invention with embodiments of the invention one, is not construed as limiting the invention.In the accompanying drawings:

Fig. 1 is the capacitance-resistance model according to telephone line of the present invention;

Fig. 2 is the flow chart according to method of testing of the present invention;

Fig. 3 is the capacitance-resistance model of telephone line during according to testing procedure S202 of the present invention;

Fig. 4 is the equivalent model of the capacitance-resistance model of telephone line during according to testing procedure S202 of the present invention;

Fig. 5 is the capacitance-resistance model of telephone line during according to testing procedure S204 of the present invention;

Fig. 6 is the equivalent model of the capacitance-resistance model of telephone line during according to testing procedure S204 of the present invention;

Fig. 7 is the capacitance-resistance model of telephone line during according to testing procedure S206 of the present invention;

Fig. 8 is the equivalent model of the capacitance-resistance model of telephone line during according to testing procedure S206 of the present invention;

Fig. 9 is the capacitance-resistance model of telephone line during according to testing procedure S208 of the present invention; And

Figure 10 is the equivalent model of the capacitance-resistance model of telephone line during according to testing procedure S208 of the present invention.

Embodiment

Below in conjunction with accompanying drawing the preferred embodiments of the present invention are described, should be appreciated that preferred embodiment described herein only is used for description and interpretation the present invention, and be not used in qualification the present invention.

The present invention has built circuit model as shown in Figure 1 according to the telephone line situation of practical application.This model comprises 7 elements, owing to consider the situation of practical application, insulation resistance and the insulation resistance between BA between AB are different, has therefore considered this factor in the present invention, has increased a parameter.Parameter shown in Fig. 1 represent respectively insulation resistance Rba, A between insulation resistance Rab, BA between AB to the resistance R ag between the ground, B to the insulation resistance Rbg between the ground and capacitor C ab, A between AB to capacitor C ag and B between the ground to the capacitor C bg between the ground.At this, should be understood that the insulation resistance Rba between insulation resistance Rab and the BA between AB because the excitation orientation of constant-current source is different and different.

Fig. 2 shows the flow chart of the method according to this invention.Describe method of the present invention in detail below in conjunction with Fig. 1 and Fig. 2.Derive for convenience and calculate, resistance all is expressed as electricity leads.

Step S202 is with B line short circuit over the ground, as Fig. 3, at this moment circuit model can equivalence be Rba Rag in parallel and Cab Cag in parallel, as Fig. 4, make G1=Gba+Gag, C1=Cab+Cag, with constant-current source the A line is encouraged then, measure the response voltage y (t) on the circuit, the stable state of constant-current source excitation is by the time measured the steady state voltage U on the circuit, algorithm computation during according to constant-current source excitation stable state goes out G1, and the algorithm computation according to the constant-current source excitation goes out C1 again;

Step S204 is with A line short circuit over the ground, as Fig. 5, at this moment circuit model can equivalence be Rab Rbg in parallel and Cab Cbg in parallel, as Fig. 6, make G2=Gab+Gbg, C2=Cab+Cbg, with constant-current source the B line is encouraged then, measure the response voltage y (t) on the circuit, the stable state of constant-current source excitation is by the time measured the response voltage U on the circuit, algorithm computation during according to constant-current source excitation stable state goes out G2, and the algorithm computation according to the constant-current source excitation goes out C2 again;

Step S206 is with AB line short circuit, as Fig. 7, at this moment circuit model can equivalence be Rag Rbg in parallel and Cag Cbg in parallel, as Fig. 8, make G3=Gag+Gbg, C3=Cag+Cbg, with constant-current source the A line is encouraged then, measure the voltage y (t) on the circuit, when waiting constant-current source excitation stable state, measure the voltage U on the circuit, algorithm computation during according to constant-current source excitation stable state goes out G3, and the algorithm computation according to the constant-current source excitation goes out C3 again;

Step S208, A line and B line is all unsettled, and as Fig. 9, circuit at this moment can equivalence be (Rba+Rbg) Rag in parallel, capacitor C, as Figure 10, order $G4=\frac{1}{\frac{1}{\mathrm{Gba}}+\frac{1}{\mathrm{Gbg}}}+\mathrm{Gag},$ With constant-current source the A line is encouraged then, wait constant-current source excitation stable state, measure the response voltage U on the circuit, the algorithm computation during according to constant-current source excitation stable state goes out G4.

The order that it will be appreciated by those skilled in the art that above three steps can change.

The present invention considers with constant-current source circuit is encouraged, have noise on the circuit, exciter response voltage on the disturbing line, in order to reduce interference to the exciter response voltage on the circuit, the present invention selects the constant-current source steady-state method of test for use to resistance test, suppose that constant-current source is I, can calculate insulation resistance R1, R2, R3, R4 according to following formula:

R=U/I can obtain according to this formula:

$\left\{\begin{array}{c}G1=\mathrm{Gba}+\mathrm{Gag}\\ G2=\mathrm{Gab}+\mathrm{Gbg}\\ G3=\mathrm{Gag}+\mathrm{Gbg}\\ G4=\frac{1}{\frac{1}{\mathrm{Gba}}+\frac{1}{\mathrm{Gbg}}}+\mathrm{Gag}\end{array}\right.$

The algorithm of electric capacity adopts the constant-current source excitation, the sampling response voltage, thus calculate capacitance.

Suppose that response voltage is y (t), in order to reduce constant-current source excitation interference to capacity measurement, the integral algorithm of employing, see following derivation:

$I=\frac{\mathrm{\ΔQ}}{\mathrm{\Δt}}=C\frac{\mathrm{\ΔU}}{\mathrm{\Δt}}$

${\∫}_{t2}^{t1}i\left(t\right)\mathrm{dt}=C*\mathrm{\ΔU}$

${\∫}_{t2}^{t1}(I-G*y\left(t\right))\mathrm{dt}=C*(U_{t2}-U_{t1})$

$\underset{t2}{\overset{t1}{\mathrm{\Σ}}}(I-G*y\left(t\right))*\mathrm{\Δt}=C*(U_{t2}-U_{t1})$

$Z=\underset{t2}{\overset{t1}{\mathrm{\Σ}}}(I-G*y\left(t\right))*\mathrm{\Δt}$

$C=\frac{\mathrm{Ut}2-\mathrm{Ut}1}{Z}$

Wherein, Δ t represents the sampling interval.

Therefore, insulation resistance Rab, Rba, Rag, Rbg and capacitor C ab, Cag, Cbg can calculate according to following formula:

$\left\{\begin{array}{c}\mathrm{Gba}=G1-G4\±\sqrt{(G4-G1)*(G4-G3)}\\ \mathrm{Gag}=G1-\mathrm{Gba}\\ \mathrm{Gbg}=G3-\mathrm{Gag}\\ \mathrm{Gab}=G2-\mathrm{Gbg}\end{array}\right.$

$\left\{\begin{array}{c}\mathrm{Cab}=\frac{C1+C2-C3}{2}\\ \mathrm{Cag}=\frac{C1-C2+C3}{2}\\ \mathrm{Cbg}=\frac{-C1+C2+C3}{2}\end{array}\right.$

Wherein, G1=1/R1, G2=1/R2, G3=1/R3, G4=1/R4, Gab=1/Rab, Gba=1/Rba, Gag=1/Rag, Gbg=1/Rbg.

Can calculate 7 parameters on the circuit thus.

In order to improve test speed, reduce the time that circuit reaches stable state, should be when using the constant-current source excitation at the resistance of the two ends of constant-current source suitable size in parallel.Can calculate according to following formula:

τ＝RC

And the step response voltage of firstorder circuit is:

$u_c\left(t\right)=R(1-e^{-\frac{t}{\mathrm{RC}}})*\mathrm{\ϵ}\left(t\right)$

Step response u _c(t) free component u _Ct(t) index law decay is pressed in increase in time, and the speed of decay is decided by the timeconstant=RC of circuit, after the time through 4 τ～5 τ, can think u _Ct(t) disappear, promptly reach lower state.

Be the preferred embodiments of the present invention only below, be not limited to the present invention, for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (6)

1. the method for testing of insulation resistance and electric capacity on the telephone line is characterized in that, comprising:

With the short circuit over the ground of the A line in two circuits on the telephone line, with constant-current source the B line is encouraged then, measure the response voltage on the described B line, by the time described constant-current source excitation stable state, measure the steady state voltage on the described B line, and measure between described A line and described B line and first common insulating resistance value and the first common capacitance of described B line between over the ground;

With the short circuit over the ground of the described B line in two circuits on the telephone line, with described constant-current source described A line is encouraged then, measure the response voltage on the described A line, by the time described constant-current source excitation stable state, measure the steady state voltage on the described A line, and measure between described B line and described A line and second common insulating resistance value and the second common capacitance of described A line between over the ground;

With described A line and described B line short circuit, then with described A line and the described B line excitation of described constant-current source after to short circuit, by the time described constant-current source excitation stable state, measure described A line behind the short circuit and the response voltage on the described B line, and measure described A line and described B line the 3rd common insulating resistance value and the 3rd common capacitance over the ground behind the short circuit;

Described A line and described B line is all unsettled, with described constant-current source described A line is encouraged then, by the time described constant-current source excitation stable state, measure the response voltage on the described A line, and measure between described B line and described A line, described A line over the ground between and the four common insulating resistance value of described B line between over the ground; And

According to the described first common insulating resistance value, the described second common insulating resistance value, the described the 3rd common insulating resistance value, and the described the 4th common insulating resistance value calculate described A line and described B wire insulation resistance value, described B line and described A wire insulation resistance value, the insulating resistance value of described A line between over the ground, and the insulating resistance value of described B line between over the ground, and according to the described first common capacitance, the described second common capacitance, and the described the 3rd common capacitance calculate described A line and described B line capacitance value, the capacitance of described A line between over the ground, and the capacitance of described B line between over the ground.

2. method according to claim 1, it is characterized in that, A line on telephone line in two circuits over the ground short circuit, with the described B line in two circuits on the telephone line over the ground short circuit, with described A line and described B line short circuit or with described A line and described B line all unsettled after, further comprising the steps of:

To described two line discharges.

3. method according to claim 1 and 2 is characterized in that, and is further comprising the steps of:

Insulating resistance value, described A line and described B line capacitance value between over the ground of insulating resistance value between over the ground of the described A line that calculates and described B wire insulation resistance value, described B line and described A wire insulation resistance value, described A line, described B line, described A line capacitance and capacitance and the corresponding standard value of described B line between over the ground between over the ground compared, and determine whether to exist fault according to comparative result.

4. method of testing according to claim 3, it is characterized in that described A line and described B wire insulation resistance value, described B line and described A wire insulation resistance value, described A line insulating resistance value and the insulating resistance value of described B line between over the ground between over the ground calculates by following formula:

$\left\{\begin{array}{c}G1=\mathrm{Gba}+\mathrm{Gag}\\ G2=\mathrm{Gab}+\mathrm{Gbg}\\ G3=\mathrm{Gag}+\mathrm{Gbg}\\ G4=\frac{1}{\frac{1}{\mathrm{Gba}}+\frac{1}{\mathrm{Gbg}}}+\mathrm{Gag}\end{array}\right.$

Wherein, G1=1/R1, G2=1/R2, G3=1/R3, G4=1/R4, Gab=1/Rab, Gba=1/Rba, Gag=1/Rag, Gbg=1/Rbg, R1 be the first common insulating resistance value, R2 be the second common insulating resistance value, R3 be the 3rd common insulating resistance value, R4 be the 4th common insulating resistance value, Rab be A line and B wire insulation resistance value, Rba be B line and A wire insulation resistance value, Rag be the A line over the ground between insulating resistance value and Rbg be the B line over the ground between insulating resistance value.

5. method of testing according to claim 3 is characterized in that, described A line and described B line capacitance value, described A line capacitance and the capacitance of described B line between over the ground between over the ground calculates by following formula:

$\left\{\begin{array}{c}C1=\mathrm{Cab}+\mathrm{Cag}\\ C2=\mathrm{Cab}+\mathrm{Cbg}\\ C3=\mathrm{Cag}+\mathrm{Cbg}\end{array}\right.$

Wherein, C1 be the first common capacitance, C2 be the second common capacitance, C3 be the 3rd common capacitance, Cab be A line and B line capacitance value, Cag be the A line over the ground between capacitance, Cbg be B line direct-to-ground capacitance value.

6. method of testing according to claim 1, it is characterized in that the time that the excitation of described constant-current source arrives stable state is by the parallel resistance value of the common insulating resistance value of circuit in the resistance value at the two ends that are connected in parallel on described constant-current source and each step and common capacitance decision.

Images