DE1089865B - Arrangement to reduce a fault current between feed lines, especially for cables and lines in underground mining - Google Patents

Description

GERMAN

In underground mining and in plants at risk of explosion, fault currents can occur between the individual conductors of a feed line occur, z. B. caused by direct or ■ resistant Short circuits lead to great dangers for people and material. There are therefore protective circuits became known that switch off the lines when a fault current occurs. The so far '' known protective circuits, however, require switching times which do not always meet the security requirements. The striving therefore goes to that Shorten switching times or withdraw the feed energy from the fault in the line in the shortest possible time. For this purpose, arrangements are made in switchgear construction to "avoid an impermissibly high arc fault energy has been proposed in which the current conductors to be monitored of the switchgear one Bypass switch (short circuit switch) is assigned and this bypass switch as a function stands for a trigger, which optically and thus already developing a fault arc recorded. The new arrangement is based on the idea of adding the individual conductors to a feed line Short-circuit occurrence of a fault current. For the high demands of underground mining and are required to ensure safety in plants at risk of explosion, the above-mentioned arrangement is sufficient but not, since an arc, once ignited, will ignite the existing explosive Mixtures can lead. There is also the risk that with feed lines that are only one-sided, z. B. be short-circuited at the feed point, the fault point from the consumer side, z. B. by running out machines, still receives a fault current, which also endangers people and material can lead.

The new arrangement represents a further development of the known arrangement, taking into account the special conditions in cables and lines. The solution is that the generator-side switch of the feed line and the consumer are each assigned a bypass switch (short-circuit switch), which is dependent on an insulation fault monitoring device, so that if a fault current occurs, the lines at the beginning and end are short-circuited within a maximum of 10 milliseconds and thus a further feed to the fault location is practically prevented. To measure the fault current caused by the insulation fault, the insulation fault monitoring device can contain a measuring element which responds to the rate of rise, the magnitude of the current, the voltage state or the phase position of the consumer current. For those of an arrangement
to reduce a fault current

between feed lines,

especially for cables and wires

in underground mining

Applicant:

Siemens-Schuckertwerke

Aktiengesellschaft,

Berlin and Erlangen,

Erlangen, Werner-von-Siemens-Str. 50

Dipl.-Ing. Karl-Heinz Thüner, Erlangen,
has been named as the inventor

Feed line at the beginning and end assigned bypass switches can be one or more Residual current monitoring devices are provided. Furthermore, depending on the type of differential protection at the beginning and end of the feed line the incoming and outgoing current can be detected, and as a function the bypass switches can be switched on from the difference in the measured currents.

For a more detailed explanation, reference is made to the drawing; it shows a schematic of the new arrangement. The feed lines R, S, T of the sheathed feed line 1 are connected to the energy feed point via the switch 2 and to the consumer via the switch 3. The bypass switch 4 is assigned to the generator-side switch 2, and the bypass switch 5 is assigned to the consumer-side switch 3. The bypass switch is connected to the three conductors of the feed line and contains a short-circuiting piece which short-circuits the three conductors of the feed line to one another when the switch is closed. For the bypass switches 4 and 5, a switch is used which has a switching time of a maximum of 5 milliseconds. A fault monitoring device is assigned to each bridging switch, the fault current monitor 6 is assigned to the bridging switch 4 and the fault current monitor 7 is assigned to the bridging switch 5

009 609/335

Bypass switches 4 and 5 used measuring elements, which detect the fault in different ways. the Fault current monitoring device 6 speaks z. B. on the amount of current and the fault current monitoring device 7 for voltage drops (voltage state). For this purpose, in the course of Feeder for the fault current monitoring device 6 provided three current transformers, their secondary windings are connected to the actual measuring element of the device. The residual current monitoring device 7 contains three voltage converters, which are connected on the secondary side to the measuring elements of the device are connected.

The mode of operation of the arrangement is as follows: If one of the two fault current monitoring devices responds, a signal is fed to the associated bridging switches 4 and 5, which leads to the immediate short-circuiting of the conductors of the feed line 1. Thus, viewed from the generator side, the switch 2 can no longer be used to feed into the fault location, since the bypass switch short-circuits the conductors R, S, T with one another with practically no resistance. Seen from the consumer side, reverse currents cannot reach the point of failure either, since the bypass switch 5 also short-circuits the individual conductors of the feed line. The main switches 2 and 3, which are normally provided, are subject to normal fault protection and are triggered after the times in the order of magnitude of 100 milliseconds.

A further development of the representation according to the drawing consists in the consumer-side as well as to couple the generator-side switch with the fault current monitoring devices directly, so that that is, according to their switching times, the switch 2 and the assigned switch 4 or switch 3 and the associated switch 5 respond. So it is formed by the producer side and the consumer side Switches with their assigned bypass switches each have a circuit group that is shared in Dependence on the residual current monitoring device.

Claims (5)

Patent claims: 1. Arrangement to reduce a fault current between sheathed feed lines, in particular for cables and lines in underground mining, characterized in that the producer-side Switch of the feed line and the consumer one bypass switch (short-circuit switch) is assigned, which is dependent on at least one fault monitoring device stands in such a way that if an insulation fault occurs, the conductors at the beginning and end within can be short-circuited for a maximum of 10 milliseconds and thus a feed to the fault location is practically prevented. 2. Arrangement according to claim 1, characterized in that the bypass switch in Are dependent on one residual current monitoring device. 3. Arrangement according to claim 2, characterized in that the fault current monitoring device Measuring elements for measuring the amount of current, the voltage state, the current rate of rise and / or the phase position of the current. 4. Arrangement according to claim 2, characterized in that that the insulation fault monitoring device the incoming and outgoing consumer current detected and the override switch as a function of a predetermined difference value turns on. 5. Arrangement according to claim 1, characterized in that the producer-side and the consumer-side Switches with their associated bypass switches each form a circuit group that is common depending on the Residual current monitoring device is standing. Considered publications:
German Auslegeschriften E 10018 VIIIb / 21c (published on March 22, 1956), E 8785 VIIIb / 21c (published on August 30, 1956);
German patent specification No. 626 818. 1 sheet of drawings © 009 609/335 9.60