RU2807456C1 - Device for monitoring resistance of railway contact network supports - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: used to monitor the electrical resistance of the contact network supports of electrified railways. The device for monitoring the resistance of railway contact network supports contains an electronic switch connected to a high-voltage pulsed power supply, a control microcontroller, an indicator, a power source and a unit for measuring and analyzing the induced potential, allowing the start of measurement at zero or close to zero values of the induced potential. In this case, the unit for measuring and analyzing the induced potential is made on a high-speed analog-to-digital converter and is connected in parallel to the input terminals of the device. A high-voltage switching power supply, a unit for measuring and analyzing the induced potential interact with a control microcontroller, one output of which is connected to the control input of the electronic key, and the other output is connected to the indicator. The control microcontroller is configured to calculate the value of the support resistance. The power source is made using rechargeable batteries.

EFFECT: increasing the reliability of measuring the resistance of contact network supports and increasing the reliability of the device.

1 cl, 2 dwg, 2 tbl

Description

Field of technology to which the invention relates

The invention relates to measuring technology and can be used to monitor the electrical resistance of contact network supports of electrified railways operating on both direct and alternating current.

State of the art

When arranging the infrastructure of the railway contact network, reinforced concrete and metal supports are used. During operation, supports are exposed to the destructive effects of various factors, such as mechanical loads, aggressive components contained in the atmosphere and soil. But the most powerful influence is exerted by leakage currents from the contact network, causing electrocorrosion of the fittings and, as a consequence, destruction of supports, leading to various emergency situations during the operation of rolling stock.

To prevent such situations in a timely manner, the governing documents, when carrying out routine maintenance, require that the electrical resistance of railway contact network supports be measured. Supports with a resistance of less than 100 ohms are considered corrosive and must be repaired immediately. (Instructions for maintenance and repair of supporting structures of overhead contact networks, Moscow, 2008, p. 14). However, due to the presence of significant induced potentials, measuring resistance using conventional technical means is not possible.

Currently, in areas of reconstruction, renovation, and new construction of railways, all-metal supports are installed on reinforced concrete foundations. Reinforced concrete supports with qualitatively improved reinforcement insulation are also used. All this led to an increase in the electrical resistance of the supports and a significant increase in the induced potential to 1600-1800 V in the measuring circuit.

The closest analogue is a device for monitoring the resistance of supports of the contact network of railways (RF Patent No. 2309060, IPC: V60M 5/00, published on October 27, 2007), which contains a power supply, an additional current source, a normalizing amplifier, and an analog-to-digital converter (ADC) , current shunt, current relay, control unit, indication unit, high-voltage pulse source, which is charged to a potential whose value is higher than the induced potential, and is discharged through an electronic switch into the load. The signal enters the control unit, in which the time it takes for the initial potential to fall to a certain specified value, which also exceeds the induced potential, is determined

The known device does not provide for analysis of the induced potential, which leads to additional measurement error due to the possible level of the induced potential exceeding the discharge threshold level of the high-voltage source of the device. In addition, measuring the resistance of all-metal supports becomes impossible due to the induced potential exceeding the capabilities of the modern element base. The complexity of the design is due to the fact that on sections of roads with direct current, measurements are carried out using the ammeter-voltmeter method, and on roads with alternating current - by the pulse method.

The essence of the invention

The technical problem is aimed at creating a device for monitoring the resistance of railway contact network supports on railway sections of both direct current and alternating current, ensuring stable operation of the device with a small scatter of measurement results.

The technical result consists in increasing the reliability of measuring the resistance of contact network supports and increasing the reliability of the device.

To solve the technical problem and achieve the specified technical result, in a device for monitoring the resistance of railway contact network supports, containing an electronic key connected to a high-voltage switching power supply, a control microcontroller, an indicator, a power source, according to the proposed solution, a unit for measuring and analyzing the induced potential is introduced, allowing the start of measurement at zero or close to zero values of the induced potential, while the unit for measuring and analyzing the induced potential is made on a high-speed analog-to-digital converter and is connected in parallel to the input terminals of the device, a high-voltage switching power supply, a unit for measuring and analyzing the induced potential interact with the control microcontroller , one output of which is connected to the control input of an electronic switch that discharges a high-voltage switching power supply to the measured resistance, and the other output is connected to an indicator, while the control microcontroller is configured to calculate the value of the support resistance according to a given formula:

R=-t/(C × ln U1/Uo), where:

R - measured support resistance,

t is the discharge time of the capacitor of the switching power supply,

C is the capacitance of the capacitor of the high-voltage switching power supply,

Uo is the initial voltage of the high-voltage switching power supply,

U1 - source voltage when equal or exceeded

induced potential of the current value on the capacitor

high-voltage switching power supply, and the power supply, made of rechargeable batteries, ensuring autonomous operation of the device, is connected to the corresponding inputs of the unit for measuring and analyzing the induced potential, high-voltage switching power supply, control microcontroller and indicator. Brief description of drawings

In fig. 1 shows a block diagram of the device, Fig. 2 explains the principle of measuring support resistance. Table 1 presents the test results on a road section with alternating current, Table 2 presents the test results on a road section with direct current.

The device consists of the following elements:

1 - electronic key,

2 - high-voltage switching power supply,

3 - block for measuring and analyzing the induced potential, made on

high-speed ADC,

4 - control microcontroller,

5 - indicator,

6 - power supply.

Carrying out the invention

The induced potential measurement and analysis unit 3, made on a high-speed ADC, is connected in parallel to the input terminals of the device. The high-voltage switching power supply 2 and the induced potential measurement and analysis unit 3 interact with the control microcontroller 4, one output of which is connected to the control input of the electronic key, and the other output is connected to the indicator 5. The power source 6 is made of rechargeable batteries and is connected to the corresponding inputs high-voltage switching power supply 2, induced potential measurement and analysis unit 3, control microcontroller 4 and indicator 5.

The device works as follows. Terminal "Cl. 1" is connected to the rail, terminal "Cl. 2" - to the descent of the grounding circuit of the support console above the protective device. The induced potential measurement and analysis unit 3, using a high-speed ADC, digitizes the input signal, measures its value, and at the moment when the induced potential is equal or close to zero, it issues a signal to the control microcontroller 4, which closes the electronic switch 1 and the potential of the switching power supply 2, representing a capacitor pre-charged to the test voltage is discharged into the resistance of the support.

The discharge of the capacitor of a high-voltage switching power supply occurs in accordance with the condition:

Where:

t - time,

U(t) - current voltage on the capacitor,

Uo is the initial voltage on the capacitor,

C is the capacitance of the capacitor,

R - load resistance.

Simultaneously with the closing of the electronic key 1, a timer for measuring the discharge time of the high-voltage switching power supply 2 is started, which stops when the induced potential is equal to or exceeds the current value of the voltage on the capacitor of the high-voltage switching power supply 2. The obtained result is recalculated into the value of the electrical resistance of the support by the control microcontroller 4 according to a given formula :

R - measured support resistance,

t is the discharge time of the capacitor of the switching power supply,

C is the capacitance of the capacitor of the switching power supply,

Uo is the initial voltage of the switching power supply,

U1 - source voltage when the induced potential exceeds the current value on the capacitor of the switching power supply.

The result is reflected on indicator 5. Power source 6, made of rechargeable batteries, ensures autonomous operation of the device. The measurement cycle ends when the induced potential exceeds the current voltage value on the capacitor of the switching power supply.

Comparative tests of the proposed device and the closest analogue were carried out on the Krasnoyarsk Railway. As a result, 150 supports, including metal ones, were examined. The resistance of each support was measured three times. The test results are shown in tables 1 and 2.

Table 1 shows the test results on a section of road with alternating current.

In areas with alternating current, when measuring the resistance of metal supports, the closest analog showed a significant scatter of readings; the data obtained cannot be considered reliable. The claimed device demonstrated stable operation with a small scatter of measurement results. When carrying out measurements on reinforced concrete supports, the spread of readings of the proposed device was also significantly less.

Table 2 shows the test results on a section of road with direct current. In areas with direct current, the inventive device also showed more stable results, which is explained by taking into account the effect of interference during measurements.

The claimed device demonstrated stable operation with a small scatter of measurement results. When carrying out measurements on reinforced concrete supports, the spread of readings of the proposed device was also significantly less.

Thus, the claimed invention makes it possible to measure the resistance of contact network supports under conditions of induced potentials of significant magnitude. Carrying out measurements with a minimum influence of the induced potential increases the accuracy and reliability of measurements. Starting the measurement at or near zero potential increases the reliability of the device.

Claims (8)

A device for monitoring the resistance of railway contact network supports, containing an electronic key connected to a high-voltage switching power supply, a control microcontroller, an indicator, a power source, characterized in that a unit for measuring and analyzing the induced potential is introduced, allowing the start of measurements at zero or near-zero values induced potential, while the unit for measuring and analyzing the induced potential is made on a high-speed analog-to-digital converter and is connected in parallel to the input terminals of the device, the high-voltage switching power supply, the unit for measuring and analyzing the induced potential interact with the control microcontroller, one output of which is connected to the control input of the electronic key , discharging the high-voltage switching power supply to the measured resistance, and the other output is connected to the indicator, while the control microcontroller is configured to calculate the value of the support resistance according to a given formula: R - measured support resistance, t is the discharge time of the capacitor of the switching power supply, C is the capacitance of the capacitor of the high-voltage switching power supply, Uo is the initial voltage of the high-voltage switching power supply, U1 - source voltage when the induced potential is equal to or exceeds the current value on the capacitor of the high-voltage switching power supply, and the power source, made of rechargeable batteries, ensuring autonomous operation of the device, is connected to the corresponding inputs of the unit for measuring and analyzing the induced potential, high-voltage switching power supply, control microcontroller and indicator.

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