DE1018136B - Protection and monitoring device for electrical feed lines in underground operation - Google Patents

Description

GERMAN

For protecting and monitoring electrical feed lines, especially for lighting systems In underground mining operations, it is known to carry the cables next to the power wires with buckets Equip protective and a monitoring conductor, in cooperation with an auxiliary voltage source cause the system to be switched off via relay arrangements in the event of faults in the line.

A proposal for the arrangement of such facilities provides for a protective and monitoring ladder one at the beginning of the line from the auxiliary voltage source To form fed loop and thereby separate relay devices for monitoring internal and external faults to relate.

The invention now brings about an improvement such protection and monitoring device for electrical feed lines with their own monitoring devices for internal and external defects. The invention consists in that the monitoring relay for internal faults has a second winding, which is in the circuit of the monitoring device for external faults, so that if there is no power The system is prevented from being switched on in the monitoring device for external faults.

The invention provides the possibility of self-monitoring the protective device for internal failure to achieve operational readiness. If this is the case for the monitoring circuit for external Errors in electronic amplification of the fault currents are provided as a further advantage the elimination of a risk to the plant, which consists in the fact that the plants after the previous Proposals the external faults are only monitored when the cathode of the amplifier tube begins to emit, which takes a certain time after switching on.

The invention will be explained in more detail with reference to the drawing, which is an example of a circuit diagram reproduces such a system. In dam in. The drawing example shown is according to a older proposal for monitoring the conductor loop consisting of protective and monitoring conductors or a differential relay with two windings is provided for protection against external faults in the line, both of which are fed together at one end from the control voltage source, while that second end of one winding across a resistor to the beginning of the protective conductor and that second end of the other winding across the supervisory conductor and a resistor to the end of the protective conductor of the line to be monitored: are connected. To increase the sensitivity to address As already proposed, this device is an electronic amplifier Protection and monitoring device

for electrical feed lines

in underground operation

Applicant:

Siemens-Schuckertwerke

Aktiengesellschaft,

Berlin and Erlangen,

Erlangen, Werner-von-Siemens-Str. 50

Kurt Wulsten, Berlin-Siemensstadt,

and Werner Schicke, Berlin-Tempelhof,

have been named as inventors

provided, which amplifies the small fault currents for their effect on the relays.

As a further improvement, in the example shown, the supply of the monitoring device voltage sources that are independent of one another are used for internal and external faults, so that they are mutual Influences from internal and external defects are largely avoided.

The voltage jellyfish for monitoring external faults is denoted by 1, while 2 is the voltage source means for the internal faults.

The line to be protected with the power wires 3, 3 and 4 contains the monitoring conductor 5 and the protective conductor 6, which are connected to the resistors W ₁ , W ₂ , W ₃ and W _A to form the monitoring circuit for external faults that controls the amplifier tube 7. In the one fed by the voltage source 8. The differential relay 9 with its two windings is located on the anode circuit of the amplifier tube.

For the monitoring of internal errors, the relay 10 is used in the circuit of the voltage source 2, the on the one hand via rectifiers 11 and 12 to the phase conductors 3 and 4 and on the other hand to the center point a voltage divider 13 lying between monitoring conductor 5 and protective conductor 6 is connected, is.

In order to avoid the voltage divider 13 influencing the equilibrium of the bridge connection from the resistors W ₁ to W _A , the resistance value of its resistors is one

709757/250

Select an order of magnitude higher than the resistance of the resistors in the external monitoring circuit. According to the invention, the current path now leads from the positive pole of the anode voltage source 8 first via a second winding 14 of the relay 10 for monitoring internal errors and only from here to the two windings of the relay 9 for external errors. The mode of operation of the system is as follows: If the auxiliary voltage sources are switched on, the tube 7 is initially not heated; there is no anode current flowing either, and the relay 10 cannot pick up because its winding 14 is not energized. The contact 15 of the relay 10 is thus open and the main contactor 16 cannot switch on. As soon as the tube 7 is heated up, the anode current of the two tube systems causes the relay 10 to respond, whereby the contact 15 is closed and the main contactor 16 sets the lighting system 17 under voltage. If an external fault now occurs, for example a _{conclusion indicated by the lightning arrow F 1} , between the monitoring conductor 5 and the protective conductor 6, the symmetry on the amplifier tube 7 is disturbed by the fact that a voltage difference arises between points 18 and 19, which increases the anode current in increases in one tube system and weakens in the other. Through this shift of the anode currents, the relay 9 with its two coils is excited and opens the contact 20. The error F ₁ thus leads to the main contactor 16 being switched off. The relay 9 now remains; pulled in as long as the error persists, as the voltage sources for monitoring this error are not switched with the main contactor 16 ..

If an internal fault occurs, for example according to lightning arrow F ₂ , the current flows, driven by the mains voltage, from the main conductor 4 via the fault F ₉ , the monitoring conductor 5, one half of the voltage divider 13, the low voltage source 2, the winding 21 of the relay 10 and the rectifier 11 back to the other main conductor 3. In this case the mains voltage is added to the extra-low voltage source 2. The current in the coil 21 counteracts the excitation by the coil 14, causing the relay 10 to drop out and its contact 15 to open and thus the system switches off. The extra-low voltage source 2 maintains a residual current via the coil 21, which causes the relay 10 to remain de-energized and thus prevents the main contactor 16 from being switched on again.

From the explanations it can be seen that both external faults F ₁ and internal faults F ₉ , F ₃ lead to the relay 9 or 10 responding . These errors F ₄ and F _{5 also} lead to a response of the relay 9, since they also cause a voltage difference between, the, points 18 and 19.

The invention is not restricted to the details of the example shown. It can · for the Monitoring devices also other elements are used. In the illustrated embodiment, however, offers the choice of a double triode for the amplification of the currents in the monitoring circuit for external faults has the advantage that in the common supply line of the differential relay flowing! Current that is supplied via the monitoring relay for internal Error is kept, practically always remains constant

Claims (7)

Patent claims: 1. Protection and monitoring device for electrical feed lines in underground operations, which contain protective and monitoring conductors in addition to the power wires, with their own practice> monitoring devices for internal and external faults, characterized in that the monitoring relay has a second winding for internal faults, which is in the circuit of the monitoring device for external faults, so that if there is no current in the monitoring device the system is prevented from being switched on for external faults. 2. Protection and monitoring device according to claim 1, characterized in that for the Monitoring devices for internal and external faults independent voltage sources are provided. 3. Protection and monitoring device · according to Claim 2, characterized in that the voltage source for internal faults on the one hand Rectifier to the main conductor of those to be mentioned Line and on the other hand to> the midpoint of a voltage divider between protective and monitoring conductor is connected. 4. Protection and monitoring device according to. Claim 3, characterized in that the resistance value of the voltage divider is an order of magnitude higher than the resistance value of the resistors in the monitoring circuit for external faults. \ ^: 5. Protection and monitoring device according to claim 1, characterized in that for monitoring a differential relay is used for external faults. 6. Protection and monitoring device according to claim 1, characterized in that Monitoring circuit for external faults has an electronic amplification of the fault currents. 7. Protection and monitoring device according to claim 6, characterized in that for the A double triode is used to amplify the fault currents. Considered publications: German Patent No. 898 029. 1 sheet of drawings © 709 757/250 10.5T