RU2264017C2 - Method for protecting railway signaling and communication equipment - Google Patents

Abstract

FIELD: electronics; protection of railway signaling and communication equipment built around semiconductor and microprocessor parts and traditional relay circuits.

SUBSTANCE: proposed method includes sequential cascaded reduction of peak overvoltage without interfering with operating frequency signals and their levels. During first protective step rate of rise of peak active pulse is reduced by means of inductive limiters made in the form of transformers. Overcurrent protection of mentioned inductive limiters is effected by means of dischargers inserted in their secondary windings.

EFFECT: enlarged protection range of equipment, including microelectronic devices, without interfering with operating frequency signals and their levels.

1 cl, 3 dwg

Description

The invention relates to protection systems for railway automation equipment, built both on semiconductor and microprocessor elements, and on traditional relay circuitry.

Railway automation equipment that ensures the safety of trains, operating at frequencies from 25 Hz to 780 Hz and at frequencies of 4545 Hz to 5555 Hz, using rails as information circuits, must be able to protect equipment, including microelectronic, from the dangerous effects of lightning discharges having values of 20-40 kV and 10-30 kA, without interfering with the useful signals arriving along the rails, both in frequency and in signal level.

To protect the equipment from the effects of lightning discharges, the threshold principle of building protection is used, at which the remaining voltage significantly exceeds the dangerous voltage for the semiconductor structure of microelectronic equipment. Moreover, the use of threshold elements, such as arresters, varistors does not provide protection selectivity according to the above principles.

Existing methods for protecting railway automation involve the use of threshold elements using thyristor-transistor and optoelectronic devices. However, this does not ensure the absolute safety of train traffic, i.e. elimination of false alarms, distortion of the parameters of useful signals in the protection devices, as well as reliability in the protection devices, leading to a disruption in the operability of the protected ZhAT equipment.

The purpose of the invention is to increase the efficiency of protection of railway equipment automation by expanding the protection zone of equipment, including microelectronic devices, without interfering with the working frequency signals and their levels.

This goal is achieved in that they reduce the slew rate of the amplitude of the acting pulse using inductive limiters, which are transformers included in the first stage of protection and protect against increasing current through these inductive limiters with the help of arresters included in their secondary windings (Fig. 1 )

As studies have shown, the destruction of equipment, in particular windings of traveling transformers upon receipt of a lightning or switching overvoltage, occurs from the dynamic influence of the amplitude of lightning and switching overvoltages when the varistors and surge arresters of standard protection equipment installed directly on the terminals of the transformer windings are activated.

The proposed protection method is a method of “soft” reducing the peak effect of the amplitudes of lightning and switching overvoltages at the input of the protection device, which ensures not only a decrease in the level of interference on the protected equipment, but also a decrease in the dynamic effect on the equipment (transformers) located before the protection.

Figure 2 presents a block diagram of a multi-stage protection device that implements the proposed method, which presents the magnitude of the output voltage 1, 2, 3, at the outputs of the protection stage (I, II, III).

A device for protection that implements the proposed method consists of three levels of protection (figure 3):

- the first stage - transformers 1, 2 with gas-filled three-electrode arresters 3, 4 included in the secondary winding with grounded middle terminals 5, 6; varistor 7; capacitor 8;

- second stage - limiting resistors 9, 10; varistor 11; capacitor 12;

- the third stage - limiting resistors 13, 14; capacitor 15 and voltage limiter 16.

The operation of the device is as follows.

When a high-voltage pulse acts on the input of the device at the initial moment of the front rise, a current arises through capacitors 8, 12, 15 installed in each stage and the primary windings of transformers 1 and 2, which act as inductive limiters. The presence of inductance reduces the slew rate of the amplitude of the acting pulse (figure 1). A further increase in the amplitude causes the operation of the varistor 7 of the first stage. In this case, the current sharply increases through inductive limiters 1 and 2, which causes the operation of gas-filled three-electrode arresters 3 and 4. A ground current of about 50-100 A flows through the ground circuit 5, 6 of the middle terminals of the arresters 3, 4 at the time of discharge, which reduces part of the energy input impulse noise. The circuit for the inclusion of arresters 3, 4 in the secondary winding of transformers 1, 2 is caused by the need for galvanic isolation of the ground circuits from the linear wires L1-L2. The galvanic separation of this circuit is necessary because of the special requirement for the isolation of linear wires in devices that ensure traffic safety in railway automation and telemechanics systems, namely, in rail circuits with tonal frequencies of 420-5555 Hz.

A further increase in the amplitude of the pulse (jump-like in the discharge in the circuit of the arresters) causes the inclusion of the second-stage varistor 11 with the amplitude limited on the resistors 9, 10. The final decrease in the level of high-voltage interference occurs at the third stage by the voltage limiter 16 to the required level with the release of energy on the resistors 1, 3, 10, 14. The selectivity of the operation of the varistors 7, 11 and the voltage limiter 16 in steps is provided by resistors 9, 10, 13, 14.

As studies have shown, the destruction of equipment, in particular windings of track transformers upon receipt of a lightning or switching overvoltage, occurs from the dynamic influence of the amplitude of lightning and switching overvoltages upon operation of varistors and surge arresters of standard protection equipment installed directly on the terminals of the transformer windings.

The proposed protection method is a method of "soft" reducing the peak effect of the amplitudes of lightning and switching overvoltages coming at the input of the protection device, which ensures not only a decrease in the level of interference on the protected equipment, but also a decrease in the dynamic effect on the equipment (transformers) located before the protection.

Claims (1)

The method of protection of railway automation, in which, in the event of an impulse noise, a sequential cascade reduction of the dangerous external overvoltage in amplitude to a threshold is performed, which does not interfere with the working frequency signals and their levels, characterized in that they reduce the rate of increase in the amplitude of the acting pulse with using inductive limiters, which are transformers included in the first stage of protection, and protect against increase current through these inductive limiters with the help of arresters included in their secondary windings.

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