SU1718322A1 - Device for protection of complete distribution device against arc short circuit - Google Patents

Abstract

The invention relates to electrical engineering and is intended to protect metal cabinets of a switchgear switchgear and a KRUN-6-35 kV cabinet from short circuits, accompanied by an open electric arc. The purpose of the invention is to increase the reliability of the device and to extend the range of operation of the OMTUCMTM AC. The technical essence of the device is to use the current increase in the windings of current relays 7 installed in an input switch circuit to close the opening contacts connected in series with the disconnecting coil and the contacts of the current relays 10 installed in the circuit of the switches of the outgoing lines in the separation as at least in one phase of the short-circuit current, for example, by means of an arcing electrode 17 and in the process of further moving the arc along the leads of the outgoing line to decrease to values sufficient s for the reset current relay 10 contacts the vent lines, the sensitivity of the current relay zagrub- L is, for example, via a shunt 11 to the values required for actuation when external short circuit disposed at the end of the protected area. 2 hp f-ly, 4 ill. tm hl 00 s ho ho p vl-y- - chK1nZP tfMWi C-ZhЈU t dfbl .t

Description

The invention relates to electrical engineering and is intended to protect the inside of cabinets and compartments of a complete switchgear (KRU and KRUN) from an open arc of 6-35 kV.

The aim of the invention is to improve the reliability of the device and the expansion of the range.

FIG. 1 shows the electrical circuit of the switchgear switchgear and the relay protection against arc fault inside the switchgear; in fig. 2 depicts an operational power supply circuit for the input switch disconnecting coil for instantaneous switching off of the switchgear; in fig. 3 shows an example of the implementation of the device in the presence of the switchgear cabinets of the K-XIII series; in fig. 4 is an example of a constructive use of an arcing electrode that provides for the complete transfer of a short-circuit current from the phase where a current transformer (CT) is installed into an arc withdrawal electrode.

The device contains (Fig. 1) TT 1 installed in the phase of a switch 2 input feeding busbars 3 with outgoing lines 4, 5, 6. A secondary current relay 7 connected to the winding of the intermediate relay 8 is connected to the secondary winding of TT 1 On the switch of each line outgoing from the bus lines, the ТТ9 is installed in a phase of the same name as the TT 1, to the secondary winding of which a second current relay 10 is connected, parallel to the winding of which a resistor (shunt) is turned on 11. Opening contacts 12, 13, 14 of the second current relay 10 lines departing from buses 4, 5, 6, closing circuit clock 15 auxiliary relay 8, the coil 16 enter the shutdown switch 2 connected in series and connected to a power source (FIG. 2).

For reliable operation of the protection of TT-power supply. Current relays are installed in the middle phase. The introduction of an additional intermediate relay 8, for example RP-323, is an example of replacing the current relay contact 7 with a more enhanced intermediate relay contact, and creating a time delay. Then, at external short circuits, the contacts of the current relays of the lines running from the buses are disconnected before the contact of the intermediate relay closes. This avoids proper shutdown of the switchgear with external faults.

FIG. 3 shows a part of the switchgear - a 10 kV waste line cabinet. The cabinet series is KH-SH. It consists of busbars 3, an arc guide electrode 17 with air insulation. The compartments 18 and 19, respectively, of busbar and relay protection are located at the top, the compartments 20 and 21, respectively, of the switch and the outgoing

lines below. On bracket 22, the TT 9 is fixed. With the lower input of the TT, the output 23 of the switch 24 contacts. To the upper output of the TT, an outlet bus 25 of the aerial power transmission line 4 is connected. But this can also be the phase of the cable with the cable outlet. Electrode 17 with TT 9 contacts only at one point - at point 26. Nowhere else does bus 25 and electrode 17 have contact points. Tire 25 is mounted on insulators 27. With wires of power transmission lines, contact of tire 25 is made through bushing insulators 28. Wires 29 are in contact with the outer insulator lead. Dielectric pads (insulation layers) 30 are installed between the bus bar 25 and the arcing electrode. At the end of the electrode 17 there is a arresting cover 31 (Fig. 4). From the busbar through the bushing 32 a current goes

on the switch through the upper plug-in contacts 33. A bulkhead 34 is used to mount the movable bulkheads needed for the repair of switches, etc.

FIG. 4 shows the implementation (in the form

example) cover 31 and bus 25. Between them are layers of insulation 30.

The device works as follows.

When short circuit, for example, at point K (see Fig. 1

and 3) the arc under the action of the floor moves to the insulators 28. The gap between the bus 25 and the electrode 17 can be changed from a value of 8h to O2, if the insulating gaps allow. Experiments have shown that at 10 kV

inside the domestic switchgear, the arc breaks from the electrode to the bus and back at values exceeding 40 mm. To keep the arc on the electrode 17, it is advisable to make the latter out of magnetic material,

for example steel. If the arc is not completely disrupted, then a current It flows through the bus 25, and a current 2 passes through the electrode 17. In total, they form a full short-circuit current kz. The selection of the current operation of the relay 10 must be made with

coarsening, so that the relay only feels the short-circuit current at the end of the protected area. If the current AND is insufficient to operate the relay 10, then the contact in the circuit of FIG. 2 lowers and closes the circuit, and contact 15 (normally open) is closed by that time, since a current of 1kz flows immediately through TT 1. However, a delay of 0.3-0.5 s can occur here. Much depends on the size of the short circuit and the rated current used by the CT. It is known that the more current on the secondary side of the CT, the faster the relay. This should be taken into account in the practice of implementing the proposed protection. If And decreases insufficiently, then it is necessary to expect movement of the short circuit current to the cover 31. The length of the cover is established by calculation, based on the speed of the arc moving at the corresponding current and time required for the operation of relays 7 and 10, etc. The case 31 allows the current 12 to increase to kz. When upgrading such protection under the conditions of existing networks, relays 10 can be sounded using shunt 11. The resistance R of which (see Fig. 1) can be calculated by calculation. In case of damage - to arc short circuit on busbars, on the approaches to TT 9, etc. biphasic short-circuit for hundredths of a second goes into three-phase short-circuit. If CTs 1 and 9 are installed in the exact same phase, then they will be put into operation through this time. Rather, TT 1 is turned on. It sends a signal to relay 7. This relay immediately or with a short delay gives a signal to close contact 15 in the circuit of FIG. 2. A disconnect coil 16 is connected via a make contact 12, 13, and 14 to a power source. Switch 2 input is disabled and the short circuit is de-energized. With short circuits, for example, on secondary contacts 33 (see, fig. 3), the arc under the action of the source, as a rule, jumps to pin 23, and the ac moves to TT 9 and further with a speed from ten meters per second at a current of 2-3 kA up to several tens at a current of 8-10 kA, etc. Therefore, if the relay 7 is operating without delay, pin 15 in the circuit of FIG. 2 has time to close and feed a signal to disconnect the coil 16 through the differing contacts of the feeder relays. If there is an exposure to the relay 7, the arc can move beyond the TT 9. In this case, the off time determines the fraction of current 12 branching to the electrode 17. If it is large enough, and the relay 10 is roughened, for example, by using shunt 11, its contacts in the circuit of FIG. 2 does not open and the switchgear is disabled non-selectively. If the fraction 12 is insufficient, then an arc should be moved to the electrode 17. Then all the current flows through the electrode 17 and the relay 10 lowers its contact. After that, the coil 16 turns off the corresponding switch. Thus, this device allows

thread effective arc protection from wall to cell wall switchgear.

Claims (3)

Claim 1. Device for protection of complex switchgear against arc short circuit, containing current transformers, designed to be installed mainly in one phase of switch cabinets of supply inputs and outgoing from busbars of lines, the first block of relay automation, connected to the secondary winding of the current transformer of the switch power input, the second block of relay automation, connected to the secondary winding of the corresponding current transformer of the circuit breaker bus line, containing a current relay, the disconnecting contact of which is connected in series with the closing contact with the time delay of the first relay control unit in the power supply circuit of the disconnecting switch of the supply input switch, characterized in that, in order to increase reliability and reduce material consumption, the current supply transformers and waste The lines from the busbars are intended to be connected to the phases of the same name. The primary winding of the current transformer of each line leaving the busbars has from the switch side to a lemma for connecting a gag block, the winding of the current relay of every second relay automatics unit has terminals for connecting shunts. 2. The device according to claim 1, which is designed so that, in order to expand the area of operation, the gripping unit is made in the form of a gripping electrode located in the cabinet along the output of the corresponding phase of the outgoing line, and is connected at one end to a current transformer terminal. 3. The device according to claim 2, is designed so that, in order to expand the scope of application, the shunt designed to connect each second relay automation unit to the winding of the current relay is in the form of a resistor. -f 1U / 3 12 s 15 J rJMl xHl-x x  12 s 15 xHl-x x Rig.2 yy-z.3 Fig.Z FiL