SU714562A1 - Arrangement for current protection of three-phase line portion from breaking one of the phase wires - Google Patents

Description

(54) DEVICE FOR TOKqBOft PROTECTING A SECTION OF A THREE-PHASE JIMHMH FROM THE OBJECT OF THE FACTORY OF WIRES

The invention relates to technology of relay protection in electrical installations, in particular, to devices for protecting a portion of a three-phase line up to 1000 V from a dfijior break from phase wires. Asymmetrical modes in the lines up to 1000 V, associated with the disconnection of phase voltages, lead to a disturbance of one process at the consumer and failure of the electric motors. In addition, the termination of prrvr yov can lead to electric fires (LA) and animal life. A device for monitoring wire breakage up to fOOO B is known, which contains a reverse sequence filter that is connected to a protection unit installed at the protected object 11}. 12. Since the magnitude of the reverse voltage at the breaking of one of the phase conductors of the line is strongly dependent on the coupling and, first of all, on the presence of the electric motor and their loading, such a device is not sensitive enough. Of the known devices, the closest in technical terms to the proposed device is protection from the reverse sequence current relay, which is installed at the beginning of the protected section 31. The disadvantage of this device is reduced sensitivity and reliability of operation in networks up to 1000 V. As the network load is 1000 V is asymmetric and has a probabilistic nature, then the setting of the negative sequence current relay must be chosen taking into account the negative sequence detuning of the normal mode. The purpose of the invention is to increase the reliability and sensitivity of the device in the network up to 1000 V. This is achieved by the fact that in a known device for current protection of a three-phase line section from breaking one of the phase conductors containing a negative sequence current filter whose output is connected to a protection unit connected With performer | Noah body, additionally introduced symmetrical three-phase artificial load.

the circuit of which includes the aforementioned filter of inverse psdyyedatnosti, and in the presence of at the end of the protected section of the line a three-phase electric motor load in the circuit 1 |

a similar reverse current filter, the output of which is also connected to the input of the aforementioned protection unit.

The drawing shows a functional diagram of a device for current protection of a three-phase line section up to 1000 V from breakage of phase wires.

At the end of the protected section of the three-phase line 1, there is a three-phase electric motor load 2 and an artificially symmetrical load 3, in whose power supply circuits current 4 and 5 reverse currents are installed after ®SUTe11§ftOew, VGAXDOM which are connected to protection unit 6, and Bbixojo; follow-up to the executive body 7.

The device works as follows.

When one of the phase conductors of the 1 dash breaks, the signal at the output of the filter 4 of the negative sequence current, which leads to the operation of block 6, is generated. protections and EXECUTIONS of the legal body 7. Subsequently ----- ---.-..... .... ...-: ...... (, GI-Y4 (, ... i.,

The scientific research institutes can be made in the form of a three-phase circuit that was created by the Saspoticbe closure, resulting in line 1 disconnection. In the event of a disconnection of one of the mains wires when the electromotive load 2 is disconnected, a negative sequence current filter 5 appears, which leads to block triggered by executive 6

body 7 and to disconnect the line T.

The need for yctuHoiBKH individual filter 4 current of the reverse flow in C | epi electromotive load 2 vyz. This is due to the fact that when one of the phase conductors of line 1 is broken and the specified load iot in idle mode, the voltage is simulated. At the output of the negative sequence current filter 5 there will be no trigger signal.

714562

The use of the proposed device will allow you to perform sensitive and reliable protection of the three-phase line section up to 1000 V from the break of one of the phase wires with offset single-phase-three-phase heating. The expected technical and economic effect will be about ISO rubles. on one set of the device. In addition, the risk of electric shock due to touching the broken wires of the air line is reduced.

Formula 3:

Claims (3)

1. A device for current protection of a three-phase line section from breakage of one of the phase conductors, containing a negative sequence current filter, the output of which is connected to a Sitsggy unit connected to an ispolzatelny body, with tHHB b7 To increase reliability and Chuvstvitelnosti in the network up to 1000 V, additionally introduced a symmetrical three-phase artificial load, the chain of which included the mentioned negative sequence filter. 2. Pop-1 device, characterized, prgO, With the purpose of increasing reliability when there is a three-phase electromotive load at the end of the protected portion of the line to be protected, a similar negative-sequence current filter is connected to the power supply circuit of the latter, the output of which is 1K se protection block. Sources of information taken into account in the examination 1.New relay protection and automation schemes for 35/10 kV package transformer substations. Selenergoproekt, M., 1971., 2. Heyfit M.E. Relay Handbook of Protection and Automation, M., 1968. 3. Kuznik Yu. S. Study of filter relays. Electrical stations. No. 7, 1975, with. 87