DE1036361B - Protection and monitoring device for electrical feed lines, preferably of lighting systems in underground operation - Google Patents

Description

GERMAN

In the main patent is a protection and monitoring device for electrical feeds In underground operations, the protective and monitoring conductors in addition to the energy cores have been proposed included, with its own monitoring devices for internal and external faults, in which 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 current in the monitoring device the system is prevented from being switched on for external faults. With an advantageous training With this arrangement, the external fault monitoring circuit has an electronic amplification of the Fault currents.

In the embodiment described in the main patent the monitoring circuit for external faults consists of one formed by four resistors Bridge circuit in the manner of a Wheatstone bridge, which is fed by a direct voltage will. The one branch of the bridge formed by the protective and monitoring conductors is used in this circuit terminated by a resistor. With this circuit, the measuring voltage is applied to the two grids fed to a double triode. Occurs z. B. an interruption of the protective or monitoring conductor one, the two grids are influenced in such a way that in one system of the double triode an anode current flows while the other system is locked. In the event of a short circuit between the protective conductor and monitoring conductor, on the other hand, is the system that generates electricity if one of these conductors is interrupted leads, blocked, and the system, which is blocked in this case, carries an anode current. In both cases due to the different currents in the two tube systems, a flow is transmitted to the two anodes of the systems connected differential relay detuned and thereby made to respond.

The two errors mentioned now occur, namely interruption of the protective or monitoring conductor and short-circuit between these two conductors in quick succession, this is initially positive Potential leading a grid of the double triode with negative potential and the initially negative Other grids carrying potential with positive potential applied. During the reversal of the potentials, both grids briefly have the same Potential, e.g. B. Zero. This removes the detuning of the differential relay and this for a short time brought to fall, so that the switch of the line to be protected is briefly closed. This puts the damaged line under tension, which is by no means desirable.

To prevent this unintentional activation of the interference protection and monitoring device

for electrical feed lines,

preferably from lighting systems

in underground operation

Addendum to patent 1,018,136

Applicant:

Siemens-Schuckertwerke
"- stock corporation,
Berlin and Erlangen,
Erlangen, Werner-von-Siemens-Str. 50

Werner Schicke, Berlin-Tempelhof,
has been named as the inventor

th line impossible to marine, the arrangement is made according to the invention such that at Application of a measuring circuit for external errors, the is fed from a Wedhsel voltage source at the beginning of the line to be protected and its end This measuring circuit is terminated via a rectifier and possibly a resistor The system of the double triode is influenced, which is connected in series with a measuring relay for external faults and the second system of the double triode for constant excitation of a winding of the differential relay trained measuring relay is used for internal faults.

One system of the double triode is influenced by the measuring circuit for external faults by a measuring voltage, which is tapped at a further resistor connected in this measuring circuit and via an input element consisting of a resistor and a capacitor to the electronic Amplifier is fed, which in turn is arranged at the beginning of the line to be protected Switching device controls via a relay. This circuit of the measuring circuit also simplifies the process of the electronic amplifier described in the embodiment of the main patent insofar as possible as a measuring relay for external ones instead of the differential relay specified there Error a simple measuring relay with only one winding can be used.

809 597/434

If now ζ. B. the line to be protected is torn out of a connected device and Drag the cable ends over metal parts or damp ground (coal) and briefly connect get, voltage pulses occur at the resistor used to take the measurement voltage so that in this way the switching device is switched on briefly at the beginning of the line to be protected can be.

Around; also such an unintentional switch-on According to an advantageous development of the invention, a threshold value rectifier is to be avoided in parallel with the input element of the electronic amplifier switched. This threshold rectifier is dimensioned so that the electronic amplifier sufficiently high for the protective device to work properly can be, however, occasional short-term voltage pulses resulting from unintentional faulty Circuits originate, are short-circuited.

An embodiment of a circuit according to the invention is described below with reference to the Drawing described.

The feed line to be protected contains main conductors 1 and 2, the monitoring conductor 3 and the earthed one Protective conductor 4.

The monitoring circuit for internal faults consists of the DC voltage source 14, which runs across the winding 24 of the differential relay 15 and the rectifiers 16 and 17 are connected to the main conductors 1 and 2 and on the other hand via the resistors 18 and 19 to the monitoring conductor 3 or the protective conductor 4 is connected. The second winding 25 of the differential relay 15 is via the system 22 of the Double triode 10 excited with a constant direct current. The necessary positive voltage for the grid of this system opposite the cathode is produced at the resistor 20. The differential relay 15 is attracted in the undisturbed state of the monitoring circuit for internal faults, since only the coil 25 excited via the tube 10 has a current flowing through it. If an internal fault occurs z. B. by a connection between one of the main conductors 1 or 2 and the monitoring conductor 3 or the protective conductor 4, a current flows in this monitoring circuit in the second winding of the differential relay 15, which compensates for the constant basic excitation and thereby this relay to the Waste brings. Due to the differential relay dropping out 15, the main conductors 1 and 2 are separated from the supply network by the contactor 27.

The monitoring circuit for external faults consists of the mains voltage transformer 5, which is on End of monitoring conductor 3 and protective conductor 4 arranged rectifier 6 and resistor 7 as well the resistor 8. In the course of the monitoring conductor 3, one or more control switches 23 are arranged. The measuring relay 9 for external faults is controlled via the system 21 of the double triode 10. This is done with the aid of a control voltage that is applied to the monitoring conductor 3 Resistor 8 is tapped and fed to the grid of system 21 via resistor 11. To the the end of the resistor 8 facing away from the monitoring conductor 3, the resistor 12 is connected, the other end of which is connected to the cathode of the system 22 of the double triode 10. At the resistance 12, a voltage drop is generated by a fixed auxiliary DC voltage that occurs when the monitoring circuit is open for external faults, which also serves as a control circuit, to a negative potential on Grid of the system 21 of the double triode 10 leads, while the control circuit is closed on the Resistor 8 dropping voltage of this voltage is connected in such a way that the grid with a positive potential is applied, and consequently an anode current flows in the system 21, which the relay 9 holds in the attracted state. Between the monitoring conductor 3 and the cathode of the System 21 of the double triode 10, the rectifier 13 is connected, which prevents ^ that at short notice When the monitoring circuit closes, the voltage pulses which then occur charge the capacitor 26 and thereby apply a positive potential to the grid of this system, whereby the Relay 9 would come to attract. In this way, an attraction of the relay 9 by unintentional faulty circuits in the monitoring circuit for external faults avoided with certainty.

Claims (2)

Patent claims: 1. Protection and monitoring device for electrical feed lines in underground operations according to patent application S 44426 VIIIb / 21c with an electronic amplification of the fault currents in the monitoring circuit for external faults by means of a double triode, characterized in that when using a measuring circuit for external faults from an alternating voltage source at the beginning of the line to be protected is fed and its end via a rectifier and possibly a resistor is completed, this measuring circuit affects a system of the double triode, which with a measuring relay for external faults is connected in series and the second system of the double triode for constant Excitation of a winding of the measuring relay designed as a differential relay for internal faults is used. 2. Protection and monitoring device according to claim 1, characterized in that in parallel to the input element of the system used to control the external fault measuring relay a threshold rectifier is connected to the double triode. 1 sheet of drawings © 809 597/434 p.