RU1792861C - Joint meter for railway lines adapted to electric power - Google Patents

Abstract

Usage: when measured in rails chains. The essence of the measurement: the butt meter contains a recorder and is connected to the rail line by three rail contacts so that the measured joint is between the first two. The joint meter is equipped with a voltage divider, a threshold element, an alarm unit, a mode switch; an amplifier with an adjustable gain and two operational amplifiers, through which signals from the first, second, and second to third rail contacts are supplied to the two inputs of the voltage divider, the recorder is directly connected to the output of the voltage divider, and the signaling unit through a threshold element - a litel with an adjustable gain, the second input of which is connected to a mode switch.

Description

The invention relates to railway automation and telemechanics and can be used in the maintenance of rail circuits.

Butt meters are known for measuring the resistance of conductive joints of a p-line line, operating on the principle of voltage drop detection on a measured resistance and a reference shunt. These components are rather cumbersome due to the cost of a shunt store, they require a lot of manipulations during the measurement process and provide low measurement accuracy.

A butt meter is also known, comprising a reading and recording device and three rail contacts mounted at fixed distances from each other and connected to the rails of the first and second

the contacts are on opposite sides of the conductive junction and the second and third are to a fixed length rail section.

The disadvantages of the butt meter are the effect on the contact resistance of the contacts, which is comparable to a measured resistance of the order of a milliom, the difficulty of carrying out mass measurements under operational conditions due to the need to perform bridge balancing operations and the absence of automatic fixation of defective joints.

The purpose of the invention is to improve measurement accuracy.

This goal is achieved in that the butt meter is equipped with a voltage divider, a threshold element, a mode switch, an alarm unit, an amplifier with an adjustable coefficient

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00 Os

amplification and operational amplifiers, through one of which the first and second rail contacts are connected to one of the inputs of the voltage divider, the second and third rail contacts are connected to the other input of the voltage divider, and the recorder is connected to the output of the voltage divider and one of the inputs of an amplifier with an adjustable gain, the output of which is connected through a threshold element to an alarm unit, and the second control input to a mode switch.

The drawing shows a structural diagram of the meter.

The junction meter includes a recorder 1, the input of which is connected to the output of the voltage divider 2 and the first input of the amplifier 3 with an adjustable gain, the mode switch 4 is connected to the second control input, and the input of the threshold element 5 connected to its output by alarm unit 6.

The first 7 and second 8 rail contacts are connected to the rails 9 and 10 on opposite sides of the junction 11, and the third rail contact 12 is connected to the rail 10 at a fixed distance Ch1 from the second contact 8. The signal from contacts 7 and 8 through the operating an amplifier 13 is supplied to the first input of the voltage divider 2, and the output of the second operational amplifier 14 connected to its terminals with pins 8 and 12 is connected to its second input.

The joint meter works as follows.

For measurements, the device is connected by rail contacts 7 and 8 to rails 9 and 10 on opposite sides of junction 11, and by rail contacts 8 and 12 to a section of rail 10 of fixed length It.

In sections of railroads with an electric track, a traction current of a certain value b always flows along the rails, while the voltage drop at the measured junction

UcT-lf ZCT

and on a fixed length rail section And

Un IT li Zp, where ZCT is the measured interface resistance;

Zp is the resistivity of one meter of tractive current rail.

These voltages are supplied respectively through the first 13 and second 14 operational amplifiers to the first and second outputs of the voltage divider 2, the output of which will be a signal

Ku U Ku Ui, li Zp

st Ј-st

 kZc

where Ku is the gain of operational amplifiers 13 and 14;

k 1 / liZp is the coefficient of proportionality.

Thus, at the output of voltage divider 2, Ug is proportional to the value of the measured joint resistance ZCT. The rail resistivity Zp is known to the traction current, and the length h is fixed and also known, which allows the scale of the recorder 1 to be calibrated directly in units of measured resistance.

When conducting mass preventive measurements and finding the place of damage in rail circuits, it is enough to know whether the interface resistance ZCT does not exceed the set maximum permissible ZcT-max value. Moreover, the value ZCT.MSX is normalized for different types of joints by the equivalent resistance of a rail of a certain reference length. For an almost instantaneous determination of whether the resistance of the measured joint meets the standards, the second channel at the output of the voltage divider 2 is used, where the signal Ug proportional to the measured resistance, after amplification by the amplifier 3, is fed to the input of the threshold element 5. If the voltage Ug is greater than the acceptable voltage for this at the junction, threshold element 5 should be triggered and alarm unit 6.-J should turn on. The voltage of actuation of threshold element 5 is fixed by Unop. so that the response of the light channel depends on the type of interface, the gain of amplifier 3 is changed by mode switch 4.

The value of the voltage drop Uoi of the traction current on the section of the rail of the threshold length for the i-ro type of joint

Uol 1t loi Zp,

where I0i is the standard value of the rail length / resistance of which is the maximum allowable for the considered} -th type of joint. Then the value of the gain of the amplifier 3 required in this case should change proportionally to the ratio Ii / t0l.

As an amplifier 3 with adjustable gain, operational amplifiers can be used. The magnitude of the gain in this case can be changed using the mode switch.

: The light channel works as follows.

before measurements by means of the mode switch 4, the type of joints used in the section is set and thereby the required value of the Gain coefficient of amplifier 3 is set. If npi / measurement it turns out that the resistance of the joint is less than the maximum permissible, i.e. is within the normal range, then the voltage at the output of amplifier 3 is not sufficient for triggering threshold element 5. If, however, the resistance is higher than what is expected, the voltage drop on it increases, causing the voltage Ug at the output of divider 2 to increase, and the voltage at the output Amplifier 3 is more stressed; triggering of the threshold element 5. The latter is triggered and includes an alarm unit b, built, for example, on LEDs that consume a very small

power. A light signal indicates that the measured joint is defective.

Experimental studies of the prototype of the enclosed joint meters for electrified railway lines under laboratory and operational conditions showed that, compared with a device of a similar purpose (prototype), the results of the measurements with the enclosed joint meter are independent of the magnitude of the transient resistances between the rails and the contacts by which the butt meter is connected to the rail lines. When carrying out measurements, it is not necessary to carry out any manipulations with switching circuit elements The instrument, a presetter type switch on the device interface provides the appearance of a light signal if the measured current is defective.

Claims (1)

The claims A junction meter for electric railway lines containing a recorder and rail contacts, one of which is connected to the rails on one side of the junction, and the second and third on the other along the rail line, characterized in that, in order to increase , it is equipped with a divider, for example, a threshold element, switch l of modes, an alarm unit, yct / lit with an adjustable coefficient; t- L. .., -,: amplification and operational amplifiers, through one of which the first and second rail contacts are connected to one of the inputs of the voltage divider, the second and third rail contacts are connected to the other input of the voltage divider, the recorder and one of the inputs of an amplifier with an adjustable gain, the output of which is connected through a threshold element to an alarm unit, and the second control input to a mode switch.