RU2564769C1 - Method for glaze ice cleanout from wires of railway overhead contact system by electromagnetic radiation - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: in this method a group of microwave heaters is used with magnetrons having frequency of 2450 MHz and open-type resonators, which are mounted in front of pantograph collector at the electric locomotive roof, at that each heater consists of two spherical metal reflectors, and the contact wire section between the reflectors is heated up to temperature of +(30…40)°C. In result of microwave radiation the glaze ice film covering the contact wire is heated and melted. At each electric locomotive cleanout of contact wire from glaze ice film is carried out independently.

EFFECT: provided normal conditions of operation for pantograph collector and excluded high-speed wear of graphite susceptors.

5 dwg

Description

One of the serious reasons for the disruption of the normal functioning of railway transport around the world is the icing of the wires of the contact network. The formation of an ice film of different thicknesses on the wires occurs under certain meteorological conditions (temperature and humidity, wind direction and speed). As a result of icing, additional mechanical loads are created that cause wire breakage, and due to the deterioration of the current collection quality, which is accompanied by detachments of the current collector from the contact wire, arcing discharges with high currents occur, which make it possible to burn the wire and damage expensive graphite current collectors and their frequent replacement. Similar phenomena occur even when a thin ice layer in the form of hoarfrost forms on the wires.

To clean the wires of the contact network from icing, they are heated by passing electric current through them from the traction substation. The specified operation is performed in some cases with the termination of the movement of trains on electric traction in this section.

Experimental studies conducted on the high-speed Paris - Lyon line showed that to evaporate water on the contact wire, the latter should be heated to a temperature of + 10 ° C for 15 minutes. During the experiment, a current of more than 600 A was passed from the traction power plant with a voltage of 26 kV through the contact wire, and the power consumption was 16 MW with a specific power of 600 W / m. (see. “Contact network icing control system” - ZhDM-online ”- 11-2002 [1]).

Another way to protect the contact network from ice is the use of a special atifriz fluid in the framework of the ProFil system (Switzerland). In dry weather, such de-icing protection is only effective from 5 to 7 days.

Closest to the claimed method for protecting contact power lines from ice is a technical solution described in the patent of the Russian Federation No. 2356148 "Device for melting ice on wires and cables of overhead lines (options)" [2].

The prototype [2] is characterized by the fact that the wires of power lines are closed and an increased current, melting ice, is passed through them. Thus, with this method, it is necessary to stop the movement of trains, which in most cases is completely unacceptable.

Thus, it can be stated that effective methods and means of combating icing wires of the contact network, especially on lines with high-speed traffic, where icing leads to the most serious consequences, do not exist all over the world.

Let us turn to the characteristics of the proposed method. Suppose that in some way, before the pantograph of an electric locomotive, it would be possible to clear the contact line of the ice film by rapidly heating it to a temperature of + 30-40 ° C, which would be accompanied by almost instantaneous melting of this ice film (Fig. 1).

Calculations show that such a heater, moving along the contact wire in front of the pantograph at an electric locomotive speed at a speed of 36 km / h or 10 m / s, should consume an energy of 20 kJ every second.

In this case, the heated section of the contact wire is completely freed from the ice film and the graphite current collector will come into contact with the wire, free from ice or hard frost. The required energy in the direction of the contact wire for almost instant destruction of a thin ice film on it can be transmitted using microwave radiation with a power of 20 kW.

Let's consider this problem in more detail. Let us first turn to the device of a household microwave oven, a schematic device of which is shown in Fig. 2, (see, for example, Didenko A.N., Zverev B.V. Microwave Energy, Nauka, 2000, [3]). In it, objects are heated by placing them inside a chamber - a rectangular resonator, in which a microwave electromagnetic field is excited using a magnetron of continuous radiation of a signal with a frequency of 2450 MHz. It is this frequency that is resonant for water molecules, at which the most efficient conversion of electromagnetic energy to heat occurs, which leads to the rapid heating of water.

We now replace a rectangular resonator with an open one with spherical metal reflectors (see, for example, L. A. Weinstein. Open resonators and open waveguides, Sovetskoe Radio, 1961 [4]). We place the resonators on the roof of a specially equipped locomotive in front of the current collector so that the contact wire is always between the reflectors in the center of the electromagnetic field. A 2450 MHz magnetron can be located in a special compartment and be connected to one of the reflectors with a coaxial cable (Fig. 3).

We take into account that the wire with respect to the moving locomotive continuously changes its location in space to some extent, which requires the correct choice of the placement of reflectors, the distance between which must be an integer number of half-waves (λ / 2 = 6.12 cm) to establish inside the resonator standing wave mode.

Thus, using the modernized type of microwave heater, it is possible to realize the idea of almost instantly heating the contact wire section and eliminating the ice film on it.

To increase the heating time for each section of the contact wire, taking into account the locomotive's speed of movement, a group of microwave heaters should be placed on its roof. Each of the heaters includes a 2450 MHz magnetron and an open type resonator consisting of two spherical metal reflectors, between which the heated contact wire moves. The number of such heaters (magnetrons) with a frequency of 2450 MHz with a power of up to 8-10 kW can be from 5 to 10, depending on the speed of the electric locomotive and weather conditions (Fig. 4).

As a result of exposure to microwave radiation, the ice film covering the contact wire quickly heats up and melts. Thus, each electric locomotive independently cleans the contact wire from the ice film, as a result of which normal operating conditions for the pantograph are ensured and the rapid wear of graphite current collectors is excluded.

We present the results of an experimental verification of the proposed method for destroying an ice film on a contact wire. A photograph of the laboratory setup is shown in Fig. 5. The installation includes a 800 W magnetron with a power supply from a commercially available microwave oven and two reflectors, which are used ground-based satellite spherical antennas with a diameter of 60 cm. A can of water, placed in the free space between the reflectors, in 2 minutes at a magnetron power of 800 W is heated at 75 ° C, and at a power of 600 W - at 40 ° C, which is about two times less than when heating the same amount of water with a closed resonator. Consequently, with an open resonator, half of the power emitted by the magnetron is dissipated into the surrounding space, but the second half is converted into heat, contributing to the rapid melting of the ice film and ensuring reliable contact of the graphite current collector with the copper contact wire.

Thus, it was experimentally confirmed that water can be heated not only with the generally accepted closed resonator, but also with an open type resonator, and, therefore, the principle of destruction of the contact network ice film using a 2450 MHz microwave generator (magnetron) with an open type resonator located in front of the pantograph.

For a better understanding of the essence of the claimed invention, the following graphic materials are provided:

FIG. 1. The block diagram of the heating of the contact wire using a heater located on the roof of the electric locomotive in front of the pantograph, where 1 is a graphite pantograph current collector, 2 is a contact wire with ice film, 3 is a heater, 4 is evaporated water.

FIG. 2. The structural diagram of a microwave oven, where 5 is a magnetron, 6 is a closed rectangular resonator.

FIG. 3. The structural diagram of a microwave oven with an open type resonator, where 7 is an open resonator with spherical reflectors, 8 is an RF-coaxial cable, 9 is the area of movement of the contact wire.

FIG. 4. The block diagram of the heating of the contact wire using a group of microwave heaters located on the roof of an electric locomotive in front of the pantograph, where 11 is a group of open resonators, 12 is a group of magnetrons.

FIG. 5. Photograph of a laboratory setup with a magnetron and two spherical reflectors.

Claims (1)

A method of cleaning ice from wires of a railway contact network by means of electromagnetic radiation, characterized in that a group of microwave heaters is used, including magnetrons with a frequency of 2450 MHz and open resonators, which are placed in front of the pantograph on the roof of an electric locomotive, each of which consists of two spherical metal reflectors, and carry out the heating of the contact wire section located between the reflectors to a temperature of + (30 ... 40) ° C.

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