SU737889A1 - Device for detecting single-phase short-circuitings in power transmission lines - Google Patents

Description

(54) DEVICE FOR DETECTING SINGLE-PHASE SHORT CABLE ON ELECTRICAL TRANSMISSION LINES. 1 The invention relates to the field of electrical measuring equipment and can be used to detect single-phase short circuits on power lines with insulated neutral. Devices are known that contain a measuring transformer for voltage, a voltage relay, a time relay and a search relay 1. The disadvantage of these devices is the interruption of the power supply to consumers due to the alternate disconnection of all, even intact, outgoing power lines of a controlled power line. The closest in technical essence is a device for detecting single-phase short circuits on power lines, comprising a measuring voltage transformer, measuring unit, switching unit, zero sequence choke, contactor, unlocking unit, signaling unit, current transformer, oil blinker switch and current protection relay 2. A disadvantage of this device is the need to momentarily shut off the damaged outgoing LINE of a monitored transmission line., s invention - exclusion power failure occurs when one-phase short circuits. This goal is achieved by the fact that a known device containing a measuring voltage transformer, a KbTopiofo input is supplied with a cbn trt: a transmission line, in each outgoing line of which a series-connected current transformer and an oil switch are connected, the control input of which is through a relay The current terminal is connected to the output of a current transformer, a blinker, a measuring unit whose input is connected to the output of a measuring voltage transformer, and the output is connected to the input of a switching unit, the choke is zero pos A terminal with a grounded zero point, the outputs of which through a contactor are connected to a controlled electric power transmission line, an alarm unit whose input is connected to one of the outputs of the switching unit. With its unlocking block, it is connected (connected to the control input of the contactor, equipped with current relays, each of the new relays 5 connected to the corresponding outgoing line between the current transformer and the input of the measuring unit, and the control output of the current relay is connected to the input of the blinker.

The drawing shows the functional diagram of the device.

The device contains a choke 1 zero sequence, contactor 2; block 3 unlock, block 4 switchings, block 5 alarm, measuring block 6, measuring transformer voltage 7, current transformers Sg, ... 8p, current relay in seconds 9, ..., 9, current relay 10,,., 10 ,,, blinkers 11,. ., 11 and oil switches 12 I 12j.

The device works as follows ...

In normal mode, the operation in the absence of outgoing lines 13, ,,. 13j controlled line. On the 14th of the side of the ground fault circuit, in the secondary winding of the measuring voltage transformer 7, made according to the open triangle scheme, the zero sequence voltage is absent. Contactor 2 is off. The zero sequence choke 1 is disconnected from the monitored power line 14.

When a ground fault is detected on any of the rest of the 13, ... 13, for example, on the outgoing line 13 in the secondary winding of the measuring voltage transformer 7, according to the voltage Uj, equal to and 3Uo / where and, the voltage of the zero sequence, the voltage that will trigger the measuring unit b, from which the voltage goes to the input block 4 switching. The switching unit 4 supplies this voltage to the unlocking unit 3, which generates trigger pulses to the control input of the contactor 2. In this case, a zero sequence choke 1 with a grounded midpoint is connected to the monitored power line 14. This leads to the fact that a controlled power line from an insulated neutral network is transformed into a network with a grounded neutral. As a consequence, on the current transformer 8, the outgoing line 13, on which a single-phase short-circuit occurs, a signal appears. Under the influence of this signal, the time of the current protection relay 9; the fault of the outgoing line 13 begins. Simultaneously, the current relay 10 is triggered by sending the command to turn on the blinker llj, and turning off the measuring unit 6. At the same time, the voltage on the 4 switching unit disappears and SO3 returns to its original position.

which leads to the disconnection of zero sequence throttles from the controlled power line. In this case, the monitored transmission line is again converted to a line with an insulated neutral, and the signal from the current transformer 8 of the damaged outgoing line 13 disappears. The timing of the current protection relay 9 stops, and it does not have time to work AND turn off the oil switch 12, the damaged outgoing line 1,3. .

The use of a fast-acting current relay in the device makes it possible to prevent short-term 5 trips of the damaged-outgoing

lines and eliminate violations of the power supply of consumers powered by this line. . -

Claims (1)

1 .. Vysochin B, A. and others. Operation and repair of electrical installations, Kiev, Harvest, 1969, p.226 (analog). 2, for 2447714/21, cl. G 01 R 31/08, according to which the decision was made .0 issue of the author's certificate, 02.02.77 (prototype).