RU2251495C2 - Device to reduce electromagnetic influence of ac electrified railway onto wire communication lines - Google Patents

Abstract

FIELD: protection of wire communication lines.

SUBSTANCE: proposed device is connected not to grounded shielded wire compensating for magnetic component of contact system electromagnetic field, but directly to communication line through differential transformers, and it provides open circuit made from ground at both sides. Communication line not connected to ground is under action of electric (capacitive) component of electromagnetic field. Proposed device changes communication line from induced magnetic component conditions into induced electric component conditions and decreases its value by supplying compensating voltage equal to induced voltage with shift of 180 el. Degrees into communication line. Proposed device contains phase regulator, regulated source, voltage transmitter responding to changes of amplitude and phase of voltage of influencing contact system and source internal resistance regulator unit.

EFFECT: provision of protection of communication line from dangerous and interference influences of contact system at reduced cost of equipment.

1 dwg

Description

The device relates to wired communication lines located near electrified on alternating current railways.

The contact network is a single-wire line with the return of current through the earth (rail), creating an intense electromagnetic field that affects the space surrounding the railway. In the area of this electromagnetic influence are wire lines. To protect communication channels from induced voltages, mainly used are differential transformers connected at the ends of the line with a grounded midpoint. However, these and many other measures do not sufficiently protect the communication channels from the dangerous and interfering influences of the contact network. When the communication line is connected to the earth, dangerous and disturbing influences from the current of the contact network arise. In all existing devices, communication with the ground is used to reduce the electrical (capacitive) component of the electromagnetic effect. It has a more significant level of induced voltage in the communication line than magnetic. The magnetic component depends on the current of the contact network and the inductive coupling between the contact network and the communication line.

A device is known for reducing the electromagnetic effects of electric railways on wire communication channels (Aut. Sv-in No. 1400922 from 12.12.1988, Bull. No. 35 from 09/23/1991). It is a complex consisting of a traction current sensor; signal processing unit (consisting of a traction current selector); phase-shifting block; block phase shift regulators; block of large-scale amplifiers; a mixer; a traction current selector and a current source supplying a signal in antiphase to the traction current in a protective shielding wire. Common is the power supply source and the phase shift unit.

There is also known a device for reducing the electromagnetic effect of electric railways on wire communication channels (Aut. Sv-in No. 1289712 from 07/29/1985, Bull. No. 21 from 06/07/1988), containing an energy supply source and a phase shift unit, which are common elements for the analogue and the claimed device.

The closest in essence to the proposed device is the device (Aut. Sv-in No. 1400922 from 12.12.1988, Bull. No. 35 from 09/23/1991). In this device, the received traction current signal is decomposed into a harmonic composition, phase shifted by 180 ° el., Amplified to the required level, added up by harmonics and fed through a source to the protective conductor.

This prototype device uses traction current compensation, which has a wide interfering harmonic spectrum (up to 61 harmonics). Currently, the use of thyristor-controlled electric locomotives increases the width of the interfering spectrum several times more and, as a result, the prototype device cannot provide compensation in the entire interfering spectrum. The selection of higher-order harmonics due to a constantly narrowing sampling band becomes impossible and is not implemented by hardware.

In the claimed device, the task is achieved by the fact that the device is connected not to a shielded wire closed to the ground, which compensates for the magnetic (random) component (as in the prototype), but directly to the communication line through existing differential transformers and creates a breakage mode from the ground on both sides . The invention solves the problem of increasing the security of communication lines from dangerous and interfering influences of the contact network while reducing hardware costs.

This task is achieved in that the device containing an adjustable source and a phase regulator, according to the invention, is connected at one end of the communication line between the ground and the midpoint of the differential transformer. Using the introduced regulator of the internal inductive resistance of the source, the communication line is transferred from closed at the ends to the ground (the midpoints of the differential transformers are connected to the ground) to isolated from the ground. In addition, instead of the current sensor, a voltage sensor connected to the voltage of the contact network and supplying a signal to the phase regulator is introduced.

The essence of the invention is illustrated in the drawing, which shows a structural diagram of a device for reducing the electromagnetic effects of electric railways on a wireline, where 1 is a contact network; 2 - communication line; 3 - differential transformers; 4 - regulated source; 5 - regulator of the internal inductive resistance of the source; 6 - phase regulator; 7 - voltage sensor; 8 - natural capacitance of the wires of the communication line relative to the ground.

The device consists of a voltage sensor 7 associated with a change in phase and amplitude in the contact network 1, issuing a signal to obtain a phase shift in block 6 and to obtain the necessary compensation amplitude in block 4, the internal resistance of which is regulated by block 5 depending on capacitances 8, and then through a differential transformer 3 into the communication line 2, which is affected by the contact network 1.

The device operates as follows: the sensor 7 creates a control signal, which represents all the linear and phase voltages associated with the amplitude and phase changes in the supply voltage of the contact network 1. From this signal, the phase 6 regulator provides a phase angle angle shift of 180 ° el. in relation to the induced voltage in the communication line 2. Then the signal is amplified in amplitude in the regulated source 4. The source 4 creates a magnitude of the amplitude of the compensation voltage equal to the amplitude of the induced voltage in the communication line. In addition, the adjustable source 4 is regulated by the amount of internal inductive resistance by block 5 to create a resonance line 8 with a natural capacitance, at which the total resistance to earth will be infinity. This is an open circuit in relation to the earth. Further, the voltage obtained through the differential transformer 3 compensates for the induced voltage of the contact network in the communication line 2.

The sensor 7 is a transformer with linear and phase voltages, receiving power from the same source as the contact network. The phase 6 controller is made according to an autotransformer circuit. Adjustable source 4 is a transformer with an adjustable transformation ratio. The regulator of the internal inductive resistance of source 5 is an isolation transformer with adjustable output resistance and transformation ratio.

The proposed device, in comparison with the prototype, reduces the impact of the contact network on the communication line, regardless of the traction current, its shape and size.

Implementation of the invention is currently possible through the use of standard equipment and units.

Claims (1)

A device for reducing the electromagnetic effects of electric railways on a wired communication line, comprising a phase regulator and an adjustable source, characterized in that a voltage sensor is introduced into it, responsive to a change in the amplitude and phase of the voltage of the affecting contact network, and a source internal resistance regulator unit, wherein the voltage sensor output is connected to the phase regulator, an adjustable source is connected between the ground and the midpoint of the differential transformer at one end of the line, the second to Heff, which is disconnected from the ground, and an internal source resistance connected between the control unit and the adjustable phase control source with the ability to transfer the communication link to the isolated from the ground due to the parallel resonance provided by the internal inductive reactance controlled source and natural capacitance line.