SU1284859A1 - Device for protecting direct current traction system from short-circuit currents - Google Patents

Abstract

The invention relates to electrified transport, namely, devices for protection against short-circuit currents in direct-current power grids, and can be used in the power grids of subways and main railways. The aim of the invention is to increase the reliability of the protection of the tram network pic (L 5

Description

current from short-circuit currents. The device contains a sensor

1 current included in the contact network

2 through an intermediate transformer 3, in parallel with which an additional wire 4 and a long-distance subscriber 5 are laid, for which a track can be used. The output of the current sensor 1 through the band-pass filter 6 is connected to the disconnecting unit 7 - a high-speed switch. The device also includes a switching device 8, a switching unit 9 of the switching device 8, a threshold element 10 and a sensor 11 of the electric field strength, and the switching device 8 you

84859

filled as an optoelectronic pair. LED 12 is a photothyristor 13, which is connected between additional wire 4 and extended instance 5. Switching unit 9 of switching device 8 consists of trigger 14, reset element 15 containing circuit RC, generator 16 clock pulses and of element 17. 17. T A network consisting of a contact network 2, an additional wire 4 and an extended earthing switch 5 is presented in the form of an electrical circuit with distributed elements 18 and 19 and mutual inductance 20 between the contact network 2 and an additional wire 4. 1 sludge.

one

This invention relates to electrified transport, viz. , to protection devices against short-circuit currents in the direct current grids, and can be used in the tram networks of the subways and main railways.

The aim of the invention is to increase the reliability of protection of a direct current network from short circuit currents.

The drawing shows a block diagram of the proposed device. . The device for fixing the direct current network from short-circuit currents contains a current sensor 1 connected to a contact network 2, through an intermediate transformer 3 in parallel with which an additional wire 4 and an earthing 5 can be used, which can be used as a track 1 current through a band-pass filter 6 is connected to a switch-off unit of a high-speed switch (not shown), a switching device 8, a switching unit 9 of the switching device 8, a threshold element 10 and a sensor 11 spine of the electric field, the switching device 8 in vtolnen vvde optoelectronic pair: si pg 12 - fototiristory 13 which is connected between

five

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0

five

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additional wire 4 and earth conductor 5

The switching unit 9 of the switching apparatus 8 consists of a trigger 14, a reset element 15, containing an RC circuit, a generator of 16 clock pulses and an I 17 element. type of electrical circuit with distributed elements 18 and 19 and the element 20 of mutual inductance between the contact network 2 and additional wire 4.

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The device works as follows.

When a short circuit occurs, the electric field decreases in intensity, to which sensor 11 responds. When the electric field reaches a certain level, threshold element 10 is triggered. As a result, trigger 14 is reset in one state and pulses pass through element 17. from the generator 16 clock pulses. Through the element And 17, the pulses are passed until the trigger 14 is in a single state. This time is determined by the parameters of the element 16. Through the element AND 17 pulses with a frequency u), which is determined by the generator capacity of 16 clock pulses, ptupat to the input of the LED 12 of the optoelectronic pair, which causes the photo thyristor 13 to open with the same frequency.

The photo thyristor 13 is connected between the additional wire 4 and the earthing switch 5. As a result of opening the photo thyristor 13, the wire 4 is switched to the earthing switch 5 with a frequency,.

In the case of switching the wire 4 to the earthing switch 5 with the frequency uJ due to capacitive and mutual inductive communication, the parameters of the elements of 18-20 tg network are changed. This leads to the appearance in the current spectrum of the contact network 2 a harmonic component of the frequency (CL), which is detected by the current sensor 1. From the current sensor 1, the signal enters the filter 6. Since the filter is tuned to the frequency LI), the signal passes through it and enters the input of the shutdown unit 7, resulting in the disconnection of the damaged section.

There are cases when a decrease in the electric field intensity occurs in the absence of a short circuit. This may be when passing an electric rolling stock in the dead zone. In this case, the decrease in the electric floor intensity is slightly

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and does not reach the trigger threshold of element 10, with the result that the shutdown does not occur.

The proposed device for the protection of a direct current network against remote short circuits makes it possible to increase the efficiency of the protection operation, eliminate dead zones and increase the electrical safety conditions.

Claims (1)

Invention Formula A device for protection of the direct current network from short-circuit currents, containing an additional wire connected in contact network, in parallel with which an additional wire and an extended earthing switch are installed, the current sensor, the output of which through a band-pass filter is connected to a high-speed disconnecting switch, in order to maintain reliability, it is equipped with a switching device, its control unit, a threshold element and an electric field strength sensor, the output of which through the threshold element m is connected to the input of the control unit switching device, wherein the switching device is designed as a pair of opto- electronic LED - fototiristory, wherein fototiristory included between the additional conductor and the earthing-adjoint prot.