RU33267U1 - Device for protecting electrical installations from abnormal operation - Google Patents

Description

Device for protecting electrical installations from abnormal operation.

The claimed technical solution relates to electrical engineering, namely to relay protection.

Known devices for relay protection, including the day of the logical repeater and resistor, connected on one side directly to the power pole and through communication cables and contacts of the external switching device with the other pole of the source of operational direct current 1.

The false operation of the repeater relay when the control cable leads to ground is prevented by selecting the response voltage of the repeater with the help of a series-connected resistor in the range from 70% to 80% of the rated voltage of the operative direct current source. The disadvantage of this device is the lack of signaling damage to the insulation of the relay circuit, as well as the rather stringent limiting conditions for the operation voltage.

Closest to the claimed solution is a device for detecting current leaks in the operational DC circuits 2, taken as a prototype.

This device is fundamentally detuned from false alarms in the event of earth faults in the receiving DC direct current circuits while providing an alarm for insulation damage of the relay follower circuit. The above is achieved by selecting the voltage of the operation of the repeaters, as well as the introduction of additional elements (diodes, relays.

resistors) for signaling an earth fault in a specific group of receiving circuits.

The disadvantage of the prototype is the lack of reliability due to the need for galvanic connection of various groups of signal repeaters, the inability to accurately diagnose a damaged relay follower circuit, as well as the significant consumption of constant current in the presence of input signals, due to the need for long-term supply of significant current for the operation of the general station control circuit isolation of the DC network.

The technical result of the proposed solution is to increase the reliability of operation by detuning from the mode of damage to the insulation of the operating current circuits, element-by-stage diagnosis, automatic monitoring of the operability of the insulation of the receiving circuits of the operating current.

The technical result is achieved by the fact that in the device for protecting the electrical installation from abnormal operation, containing a repeater relay connected in series with the contact of the switching device, the output contact of which is designed to connect to the logic controller circuit, a constant voltage source, voltage divider, alarm relay, first the winding terminal of which is connected to a common point of the voltage divider, the second to the ground electrode, an additional controlled current source, voltage relay, Therefore, the first input of the controlled current source is connected to the second terminal output of the switching apparatus, and the first output is connected to the first terminal of the repeater relay coil, the voltage relay input is connected to the first input of the current source, and its first output is connected to the second input of the current source, and the second output connected to the second output of a controlled current source and connected to a constant voltage source.

The essence of the proposed solution lies in the fact that by introducing into the device a controlled current source, voltage relay and their original connection, the detection and signaling of the abnormal mode of operation when the control cable leads are shorted to ground, which are designed to connect to the inputs of relay protection devices, having significant (more than 50 kOhm) input resistance, while ensuring the minimum permissible current value through the contact of the switching device, which increases the reliability of the function Relation protection system as a whole.

In FIG. 1 shows a structural diagram of the inventive device, where the following notation:

1- contact switching device;

2- controlled current source;

3- relay repeater;

4- voltage relay;

5,6 - resistors of the voltage divider 7 - alarm relay; 8.9- contacts.

10- voltage divider;

11 is a diagram of a station-wide insulation monitoring of a DC network The device (figure 1) consists of a contact switching device 1, the second output

which is connected to the first input of the controlled current source 2, and the first output to the output of the repeater relay 3. The input of the voltage relay 4 is connected between the current source and the contact of the switching device. The first output of the voltage relay is connected to the control second input of the current source, and the second outputs of the voltage relay and current source are connected to the negative pole of the DC power source.

the device also contains a circuit for the general monitoring of the insulation of the DC network 11, which is a voltage divider 10 of two resistors 5 and 6, to the midpoint of which is connected an alarm relay 7, the second output connected to the terminal for connecting the ground electrode. The contact 8 of the relay 3 is connected to the logic controller circuit. Pin 9 of the station-wide alarm relay 7 is used in the station-wide signaling circuit for an insulation fault in a DC network.

The inventive device operates as follows.

In the absence of an earth fault in the operating direct current network when the contact 1 of the switching device is closed, the controlled current source 2 provides the necessary minimum current for breakdown of the oxide film and reliable operation of the contact. The current value is sufficient for long-term operation of the repeater relay 3 and is set by means of a voltage relay 4, the output of which controls the current source. After a certain time, the current through the contact decreases to reduce consumption from a DC power source (battery).

In the event of an earth fault between terminal 1 and the current source, not the full operating voltage is applied to the input of voltage relay 4, but only part of it. The voltage relay 4 trips and acts on the source of current, the output current of which becomes sufficient for the operation of the general station control circuit isolation of the DC network, but insufficient for the long-term operation of the repeater relay 3. The relay switches to the pulse operation mode, fixing the occurrence of a ground fault.

The alarm relay 7 with its contact 9 gives a signal to the personnel on duty about a malfunction in the DC direct current network, preventing the long-term operation of the electrical installation with an abnormal operating mode. 1. 2. Sources of information: Collection of guidelines for the operation of energy systems. Electrical part. M., "Energy, 1981" A device for detecting current leaks in operational DC circuits. Description of invention to copyright certificate. SU No. 1464238

Claims (1)

A device for protecting the electrical installation from abnormal operation, comprising a repeater relay connected in series with the contact of the switching device, the output contact of which is designed to connect to the logic controller circuit, a constant voltage source, voltage divider, alarm relay, the first winding of which is connected to a common point a voltage divider, the second - to the ground electrode, characterized in that it is additionally introduced a controlled current source, voltage relay, and the first input the controlled current source is connected to the second terminal output of the switching apparatus, and the first output is connected to the first terminal of the repeater relay coil, the voltage relay input is connected to the first input of the current source, and its first output is connected to the second input of the current source, and the second output is connected to the second the output of a controlled current source and is connected to a constant voltage source.