SU1645184A1 - Device for measuring conductivity of rail line insulation - Google Patents

Abstract

The invention relates to railway transport and can be used to measure from a vehicle the conductivity of insulating individual sleepers, grounding structures on a rail, insulated posts, and also to detect foreign metal objects or objects with metal parts located under or near the rail. and endangering the movement of trains or disrupting the operation of automatic locomotive signaling. The purpose of the invention is to improve accuracy by reducing the effect of currents in a rail lining. A generator 1 of measuring frequency is connected with rails 2 and 3, and receivers 4.5 are installed above the rail, each of which is designed as two inductive coils located obliquely on either side of a vertical plane passing through the longitudinal axis of the rail 2. 5 or . /; h (I C

Description

but

sixteen

IL

/ J

Zy.

15

18

FL / FTG one

31

The invention relates to railway transport and can be used to measure from a vehicle the conductivity of insulating individual sleepers, grounding structures on a rail, insulated posts, and also to detect foreign metal objects or objects with metal parts located under or near the rail. and may pose a danger to train movement or disrupt the operation of automatic locomotive signaling (ALS).

The purpose of the invention is to improve accuracy by reducing the effect of currents in a rail lining.

On -fig. 1 shows a functional scheme of the device; in fig. 2 - vector diagram of currents and voltages in the presence of a metal object under the sensor and the absence of current leakage from the rail; in fig. 3 -

vector diagram of rail-ground voltage, currents in the rail and point of leakage from the rail; in fig. 4 - - the location of the coils of the sensor relative to the rail rail lining and foreign metal object under the rail, side view; in fig. 5 shows section A-A in FIG. four.

The device contains a measuring frequency generator 1 connected to rails 2 and 3, receivers 4 and 5 connected to selective amplifiers B6 and 7, which are connected through frequency multipliers 8 and 9 to a phase meter 10 connected to a two-pole recorder 11, for example, a switch device with a zero in the middle of the scale.

FIG. 1 also shows a metal object 12 and sleepers 13-15 with metal linings 16,17 and 18

Each inductive sensor consists of two inductive coils 19 and 20, connected according to the current I, (I) in the rail.

As a phase meter 10, a digital phase meter with a direct conversion is used a phase shift — time interval — constant voltage, taking into account the voltage sign. Such a phase meter contains input blocks at the input; therefore, the signal at the phase meter output depends only on the phase shift of the compared voltages and does not depend on their amplitudes.

844

 The device works as follows.

From generator 1 in rail 2, a current flows which induces an emf in rail 2, receivers 4 and 5, pads 16-18 and in the desired metallic object 12. All induced emfs are out of phase with the current in the rail by 90 °,

The voltages from the EMF in the receivers 4 and 5 after amplification and filtering in the selective amplifiers 6 and 7 are fed to the multipliers 8 and 9 frequencies. When multiplying by n times the frequency f of two voltages shifted with each other by an angle (0, voltages appear at the outputs of the frequency multipliers shifted with each other by an angle ntp.

Thus, due to the use of frequency multipliers, a sufficiently large phase difference of the signal voltages is obtained at both inputs of the phase meter with a small phase difference of the EMF of the signal induced in the receivers.

At the output of the phase meter 10, a DC voltage appears, which is proportional to the phase shift pSp.

between the voltages at its inputs.

i

If there is no current leakage from the rail section between the receivers 4 and 5, then the phase shift between the currents Ij and 1.2 in the rail below the receiver is zero

% If in the absence of leakage current (), receivers 4 and 5 are located between the sleepers so that the receivers are not affected by loop currents in the linings, and there are no foreign metal objects in the sensitivity zone of the device, then EMF E and Eg are induced in the receivers. from currents 1 (and 1 in the rail, coinciding in phase with each other (Fig. 2), so in this case the phase shift between E and E is zero, the voltage at the output of phase meter 10 is zero and recorder 1 shows zero.

If at D1 0 the receivers 4 and 5 are located between the sleepers, and under the receiver 4 there was a metal object 12, then on, the receiver 4 will have currents I in the rail and 1 in the metal object, and on the receiver 5 only current 1 in the rail

i izТок Т ц induces in a metallic, subject EMF Em, lagging behind 1 c by 90 °, and from Em in% of subject 12, a circuit current 1M occurs, lagging behind Ew by

l1

& 70-80 °, and from 1 (in the 90s + 0 (160-170 ° m (Fig. 2).

In the receiver 4, EMF E is induced, from current 1 in the rail and E from the current IMB to a metallic object, and in receiver 5 only EMF E from current 1 in the rail is induced, and E and E coincide in phase, but in amplitude may not be equal (Fig. 2). The inequality E, and E when possible due to the different displacement of the sensors relative to the rail when the device moves.

The total emf in receiver 4 is equal to EU E, + EMC. As can be seen from FIG. 2, the induced EMF E / J in the receiver 5 is ahead of the phase E c by the angle C (with 4, a constant voltage, such as positive polarity, appears at the output of the phase meter 10 EMF 2 and ESC proportional to the angle O {5p, and the recorder arrow 11 deviates from zero in the middle to the right.

As the device progresses

(in Fig. 1 to the left) the metal object 12 will be under the receiver 5, now the receiver 5 will be affected by the current 10 in the rail and the loop current 1d in the desired object, and the receiver 4 will be affected only by the current in the rail i, equal to the current 1 .

The current in the rail will induce 5 EMF U in the receiver, and the loop current 1 in a metal object will induce EMU EM 5 in the sensor 5, while induced in the receiver 4 EMF E, ahead of the total “

EMF Е E, j + EMЈ in the receiver 5 at the angle 0, .., equal in magnitude and opposite in sign to the angle 0 /,).

As a result of the effects on the phase meter 10 EMF E (and the EC5, a constant voltage appears at its output, equal in magnitude and opposite to the polarity of the voltage when the receiver 4 is over the desired object, the arrow of the recorder 11 deviates from zero middle left.

Thus, a sign of the presence of a metal object in the absence of leakage current is that when the device advances along the rail for a segment equal to the distance between the receivers, the recorder at the beginning of the segment gives a positive polarity indication, and at the end of the segment the same largest, but negative polarity.

846

If there is a current leakage from the section of rail enclosed between the receivers, the equality of checks I and 1 "in the rail under the receivers is violated. Current 1 from generator 1 is branched to current In in the rail and leakage current H1 (Fig. 3), which is determined by Ohm's law.,

U uH YP-r

(D

5 20

five

}about

0

five

Q:

five

where Up-r. rail-ground voltage

at the leak;

Yp ,,, - the measured concentrated conductance of the rail-to-ground insulation is practically active. Consequently, the leakage current UI almost coincides in phase with the voltage Up. city (Fig. 3).

The leakage current i.1 from rail to rail is determined similarly. I

The complex input resistance of a rail circuit is inductive in nature, so a current of 1 l is lagging in phase from the voltage Up--, and therefore from the current DT.

Thus, in the presence of a leakage current on the rail section between the receivers 4 and 5, the current I2 lags behind the current 1.1 ,, + D1, while the current induced by the 1g EMF of the receiver 5 lags in phase from the E induced in the receiver - +. 15 as a result of the action of EMF E, and K. on the phase meter 10 in the absence of a metal object at the output of the phase meter there appears a constant negative polarity voltage, which is displayed on the two-pole recorder 11 by a deviation of the arrow to the left of zero.

If the leakage current is outside the rail section between the receivers, the device does not react to this leakage current, since in this case the current in the rail is the same under both receivers.

Thus, a sign of the presence of a leakage current in the absence of a metallic object is that when the device advances along the rail for a distance equal to the distance between the receivers, the recorder 11 gives only one indication, and a negative polarity.

The higher the measured concentrated conductance of the Yn insulation. , the greater the current D1, the stronger the deviation of the arrow of the recorder 11, and therefore the left side of the recorder's scale can be calibrated in units of conductivity - Siemens.

It is possible, although rare, when there is a current leakage from the rail to the ground in the presence of a metal object. In this case, when the receiver 4 is located above the metal object and if there is a leakage of current from the rail section enclosed between the receivers, the loop current Iw in the metal object and the leakage current D1 from the rail will act on the device through the rail 14 into the ground.

Depending on the ratio of these effects, the recorder 11 gives an indication of either positive or negative polarity.

At the moment of being above the metal object 12 of the receiver 5, only the circuit current of 1 dd will act on the device and the recorder 11 will give an indication of negative polarity, which differs in magnitude from the value when it is above the metal object of the receiver 4.

Therefore, a sign of the presence of a metal object in the presence of a leakage current & I from the rail is that the recorder 11 on the length of the path of the device, equal to the distance between the receivers, gives two readings, different in magnitude.

Thus, in the three cases considered, the response of the recorder C is different, which allows detecting a metal object both in the presence of a leakage current and in its absence, as well as measuring the insulation conductivity in the track circuit in the absence of a metal object.

If the distance between the sleepers is equal to the distance between the receivers, the loop currents in the pads induce the same emf in both receivers and the recorder 11 does not respond to the pads.

However, a slight shift of the sleepers is possible, which can cause an imbalance in the effect of the contour currents in the pads on the device. To reduce this effect, the coils 19 and 20 of each receiver are set at an angle at which the continuation of the axis of the coil passes through the center of the cross-sectional vertical section of the pad (Fig. 4). In this case, the continuation of the axis of the coil 19 (20) passes through the center of the loop current 1 "in the lining, which reduces the value of the emf induced by the current 1I in the coil.

In the process of moving the device along the rails, the horizontal displacement of inductive receivers 4 and 5 may vary, especially in curved sections of the path, which can cause imbalances in the effects of loop currents in the pads on the device, even if the distances between the sleepers and the receivers are equal.

To reduce this effect, each inductive receiver is made of two coils 19 (20), installed symmetrically about the vertical axis of the rail (Fig. 4).

If the inductive receiver is shifted relative to the vertical axis of the rail, for example, to the right, the continuation of the axis of the coil 19 will cross the plane of the loop current 1p, substrates above the center of the current loop 1Л, and the coil 20 - below the center. As a result, in both coils 19 and 20 of the receiver an emf of the same magnitude and opposite in phase will be induced by a circuit current. Since both coils of the receiver are connected according to, the induced currents 1 of the EMF in the coils are mutually destroyed.

Claims (1)

Invention Formula A device for measuring the conductivity of the insulation of a rail line, containing a measuring frequency generator connected to the rails and installed above the rail at a distance equal to the distance between the axles of the co-sleeper, two measuring frequency receivers having each inductive coil, the winding of which connected through a selective amplifier and frequency multiplier with a corresponding phase meter input, and a recorder, in order to improve the accuracy by reducing the influence of currents in the rail track, each minutes snabzhenSdopolnitelnoy inductive receiver coil winding which is connected in series and in accordance with the first winding between it and the selective amplifier, wherein each receiver coil arranged symmetrically relative to the vertical plos9164518410 the bone passing through the acute angle of the longitudinal with the top of the rail cross with an inclination from it and with the formation of the longitudinal axes of the roll, the cross section of the vertical and transverse axes of the lining. T 5-4 Fm.g () . Editor A.Dolinich Compiled by E.Kondratenko Tehred S.Miguno.va nineteen; 20XL L sixteen FIG. ./ Y // 7 V16 FIG. five Proofreader L. Beskid