CS201106B1 - Connection of the d.c current feedbacks from the electric traction rails - Google Patents

Description

DESCRIPTION OF THE INVENTION

THE REPUBLIC K ’TO THE CERTIFICATE OF CERTIFICATE

(61) (23) Show Priority (22) Registered 15 12 72 (21) PV 8622-72 201 106 (11) (Bl) (51) ΙηΐΟ.’Β 60 II 5/00

OFFICE OFFICE

AND DISCOVERIES (40) Posted on 29 02 80 (45) Published 01 03 83 (75)

Author of the invention HAS BEEN PURCHASED LIBOR ing., BRNO ♦ (54) Connection of direct current ducts from electric traction rails 1

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the connection of direct current ducts from electrical track to reduce the corrosive effects of stray currents on underground facilities.

Existing DC electric traction systems are used to conduct reverse flow steel tracks that are not insulated from the surrounding soil. This leads to the direct current leakage from the rails to the ground, which, like stray currents, spreads through underground metal devices, especially pipes and cable sheaths. In places where stray currents come out of storage facilities into the surrounding soil, electrochemical corrosion is created, which quickly disrupts the metallic material of pipes and cables, causing high material damage, but mainly endangering the health and lives of citizens when leaking dangerous media transported through the pipeline and cables. In cities with frequent DC rail traffic and a railroad track, DC stray currents emerge into the surrounding soil at the points of connection of the return cables, or in the locations following the movement of the vehicles, according to the polarity-control system and the rails. wherein the longitudinal conductivity of the tracks has been lost, for example, by rail breaks, by interruption of the contact clutches and the like, further in all locations with increased track substrate conductivity. In the soil, these streams enter unprotected portions of metal conduits and cable sheaths, where they continue to pass through other pipelines and cables at the point of approach and crossing, and bypass flanges 201 106 2 of SOI 100 and clutches and come out of attacked storage facilities near rails back to track *

In all places where the DC output reaches, an electro-hemi-cocoon is created proportional to the current and duration of the current. When the current or alternating current flows through its changing sense, the electrochemical action is governed by laws other than the direct current. Thus, it is shown that such currents are considerably less hazardous in corrosion than at direct current. According to world-wide research and statistics, such currents have only a few corrosion damage values compared to those of direct current at the same current density on the metal surface.

Reducing the effects of DC stray currents on the affected underground facilities is achieved by passive and active protection, for example, by providing non-corrosive non-conductive coatings and coatings to metal pipes and other storage devices, piping currents from electrical polarized and non-polarized drainage, and attaching storage devices to sacrificial electrodes or by charging external electrical sources to the negative potential of the surrounding soil, and likewise, no measures known to the prior art and economics available to date can completely prevent the entry and exit of stray currents on storage devices and substantially reduce the harmfulness of their effects; The aforementioned active protective devices favorably affecting the limited parts of the protected devices may adversely affect the corrosion of the other unprotected cutters deposited in the tight joint protected by me. Known technical means of rail traction operators as sources of stray currents are aimed only at reducing the current leakage from rails by increasing the longitudinal conductivity of rails, increasing the number of exhaust air conduits, rails are laid on less conductive subsoil, lines are covered anti-wetting of rails by surface waters, decreasing the potential difference between rail tracks and the like, Most of these measures are not sufficiently and permanently effective because the growth of electric rail transport mainly in cities with the operation of new vehicles with high current drawbacks is contrary to immediate the transfer capability of the return lines, including the steel rails, and also because the rail bedding becomes more conductive against the ejection state due to the increase in the salt content of the soil and the waterlogging. Thus, the technical conception of all measures to reduce the corrosion effects on storage facilities by both the rail transport operator and the storage device users is directed to stray stray currents, or? electric traction mainly in the town and its agglomerations has been since the beginning of its existence equipped for the operation of DC vehicles and their feeding from stationary DC sources - substation, while in the near future it does not expect the introduction of AC traction into urban rail transport. This is the difference between the current rail electrification, which is done exclusively by alternating current, whose conduction by non-insulated rails does not make such a problem in terms of corrosive action, as in a direct current. The above-mentioned stray direct current currents in underground storage facilities reduce the involvement of direct current ducts from traction electric tracks 201 100 in that the return cables are cyclically coupled in the converter to the reverse flow circuit of the invention. This switching of the return current line already at a small frequency will result in a change in the current flow direction both in the rails and in the direction of the flow of stray currents of the underground storage facilities, while the existing power system and the DC drive remain unchanged. The connection according to the invention periodically changes the locations of the current output on the storage devices where the flow example is interfered with from the pipeline to another pipeline, at the pipeline joints, at the point where the pipeline cuts the current path between the track and elsewhere, while the polarization is changed and depolarization, to change the critical current density on the affected surface of the cov. In accordance with the aforementioned differential effects of AC and DC, the storage device is thus subjected to substantially lower corrosion effects, similar to those of a classically alternating stream, which is determined not only by the product of the current and its duration, but also by the frequency of alternating current, aggressiveness soil environment, storage material material, critical current density on the metal surface, pipeline impedance, track and other influences. FIG. 1 illustrates an exemplary circuit according to the invention on two reverse cable-contact methods; FIG. 2 shows another circuit for commutating the current in the rail in a non-contact manner. By connecting the cable Z1 with the switch S (FIG. 1), the return current J consisting of a plurality of vehicle streams is guided as a current JK, in the same sense the stray current J3 propagates to the pipes P1 and P2, and in the anodic areas marked + causes corrosion on the rails near bones of the point A, further on the left side of the flange coupling 6 of the pipe P1. then at point D, where there is current interference from line P1 to line P2 and at point E, where current from line P2 exits to track K. By switching switch S to cable Z2, the sense of current in wheels K from point B is reversed to point A, thereby also changing the direction of the stray current JK indicated by the dashed line. As a result, the position of the anodic points that occur at the rails at point 3 also changes to line P2 at point D, further to the other side of flange connector G and at point F to line P1. The cyclic switching of the individual return cables with the overlapping of the two cables turns periodically to change the sense of current in the rails and at the same time to change the luminescent currents in lines P1 and P2. In order to reduce the corrosion attack on interference sites up to 10% in alkaline soils, a change in the sense of current once per 2 seconds is sufficient, in acidic soils the corrosion is reduced to 20% DC. The current switching frequency can be changed in the converter M by a technical device of the switch -S up to several hertz. As switches S, for example, contactors or thyristors can be used, which can be programmed to control the switching time as well as the time for overlapping of multiple cables. The reverse current commutation can also be achieved by contactless permanent wiring according to FIG. 2, so that in the converter, each of the three anode or cathode branches of the rectifier U is connected to the return cables Z1, Z2, Z1, instead of the conventional return pole. are resistively aligned

Claims (1)

201 100 with a straightening resistor R, wherein the rail K thus forms a return pole busbar. In Fig. 2, the individual phase currents are indicated by a solid, dashed and reddish line after rectification. return lines and for a different network configuration than is indicated and described in the examples above. Γ?. 2 2 -L. · Wiring of return lines with the same reduction of corrosion effects of biodegradation, heat and heat • X * * - - * "· · 'Τ. .po ^ er according to point 1, mark: · >> ν connected by a switch (3> · M. / / -i i- po-ile .i., conf. r 5 2 j * i vru 'lezu z -.- .following the family or other branch of the multi-phase prints the (-) Ϊ Ϊ drawings