SU1377953A1 - Device for protection of autotransformer against short circuits - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to increase the speed of protection of the autotransformer during external short circuits (short-circuit). The purpose of the invention is achieved by the fact that in the protection of outgoing lines, the reverse sequence power relays 6, 7, 8 are additionally introduced. The connection of the contacts installed on the autotransformer of the reverse sequence (current relay sample last 9 and power relay) was introduced. 10) and contacts additionally installed on the outgoing lines of the power relay of an inverse sequence so that according to the state of the contacts of the indicated power relays with asymmetrical short circuit. recognized k.z. on women or outgoing connections, and the fact of short-lived recognized by triggering. In addition, a backup action was taken to disable the autotransformer under the action of line protection. 2 Il. (L

Description

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The invention relates to the relay protection of power supply facilities and is intended to ensure the disconnection of an autotransformer (AT) in the event of failure of its basic protection or the protection of adjacent elements during asymmetrical short circuits (CC).

The purpose of the invention is to increase the speed of protection of the autotransformer with external short circuits.

Consider the operation of the proposed device on the example of an autotransformer connected to buses, from which there are three connections.

FIG. Figure 1 shows the scheme of a protected autotransformer connected to high-voltage tires with outgoing connections, as well as the placement of protective measuring bodies, i.e. current and power direction relays; in fig. 2 - diagram of the operational protection circuits. The autotransformer 1 and the outgoing connections 2-4 are connected to the buses through the switches 5-8 of the negative sequence current relay 9 and the reverse sequence power direction relay 10 are connected to the transom

current format, installed in the center of current 9, the closure of the corresponding

35

40

pi AT and reverse sequence power relay 11-13 connected to current transformers of the respective connection. The closing contacts 14-18 of the power direction relay 11-13 are respectively closed when the power relay is oriented towards the tires, the closing contacts 19-21 of the power relay are respectively closed when the power relay is oriented towards its connection. The opening contacts 22 of the power direction relays 10 and 23, 24, 25 of the power direction relays 11-13 are oriented towards the connections. Closing contact 26 current relay 9,. connected in series with the windings of the first time relay 27 and the windings of the time relay 28-30 connections 2-4. 31 - winding additional time relay. 32, 33, 34 - make contacts of time relays 28, 29, 30. Closing contacts 35 and 36 of time switches 27 and 31 form a circuit of disconnecting switch 5. Closing contacts

45

contacts 14 and 26 and creating a circuit p of time 27, which is triggered by holding time t equal to tgj.

With a short circuit at point K (on tires), it crashes. At least one of the power directions is 10-13 and closes its corresponding contact of the contact group 15-18. The opening contacts 22–25 remain closed, which creates a time relay circuit 31, which, with a time lag & t, closes its contact 36 and disconnects the switch 5.

Thus, the proposed device for protecting the autotransformer from external short circuits can reduce the turn-off time when an external short circuit occurs.

F. formula

Device to protect the autotransformer from external short circuits, containing a reverse current relay

37-39 form off-off sequence and power relay circuits

2

and short circuit

on tires (points 2 (point K1) and K2).

In the first case, the power direction relay 11 is activated and closes the contacts 19, forming a circuit through the winding of the time relay 28 and the closed contact 26 of the current relay 9 (provided that the current in the AT circuit trips the current relay 9). Time relay 28 closes its contact 37 in the trip circuit of switch 6 with time delay of connection protection 2 (i.e. equal to the maximum time setting of all protection of this connection t j,). In the event of a failure, the bayonet switch 2 turns off the circuit breaker 5 in the AT circuit as a result; closing contact 36 of time relay 31, which is triggered after time At after closing contact 32 of time relay 28. The delay time t, in this case will be equal to

ti

H +

Jt.

In case of failure of the power relay 11, the protection works as a known device: the power relay 10 is activated,

pins 14 and 26 creating a time relay circuit 27, which operates with a time delay t equal to tgj.

When a fault at point K (on tires) is triggered. At least one of the power direction relays is 10-13 and closes its corresponding contact from the contact group 15-18. The opening contacts 22-25 remain closed, which creates a time relay circuit 31, which closes its contact 36 with time out & t and shuts off the switch 5.

Thus, the proposed device for protecting the autotransformer against external short circuits makes it possible to reduce the tripping time in case of external short circuits.

F. formula

Device to protect the autotransformer from external short circuits, containing a reverse current relay

power sequences and relays

6-8 readers.

The operation of the device is based on an asymmetric short-circuit on the connection sequence, installed on each side of the autotransformer, the first time relay, whose winding is connected in series with the current relay and power direction contact terminals connected in series, and the time relay contact is connected to the circuit breaker side, power relay direction of reverse order, two-way action on the number of waste connections from the tires aprons of the autotransformer, the current circuits of which are connected to current transformers of the respective connection, and a circuit consisting of contacts of the direction of power of the connections, oriented in the direction of buses, connected in parallel with each other and the closing contact of the reverse sequence power relay of the autotransformer, is connected to the winding of the second time relay, oriented in the direction of the tires, and connected in series with the series-connected disconnecting contacts of the power relay, oriented in the direction of the villagers

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No

ti, and the opening contact of the reverse sequence power relay of the autotransformer, which also has a two-way action oriented towards the autotransformer, the closing contact of the second time relay is connected parallel to the contact of the first time relay,

characterized in that

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in order to improve speed in case of external short circuits, the closing contacts of the power direction relays oriented towards the network form parallel circuits from the series-connected mentioned contacts and windings of additionally introduced time relays according to the number of outgoing connections that are connected to the short-circuit contact of the current relay, the first make contacts of additional time relays are included in the tripping circuit of the corresponding switches, and the second contacts form parallel circuits connected via been consistent with the winding of the second timer.

Claims (1)

Claim A device for protecting the autotransformer from external short circuits, containing a reverse sequence current relay and a reverse sequence power relay installed on each side of the autotransformer, the first time relay, exchanges 27 and 31 form a circuit for disconnecting switch 5. Short-circuit contacts 37-39 form a trip circuit ³³ switched ents 6-8. We explain the operation of the device using an example of asymmetrical short-circuit on the connection of a coil of which is connected in series with the closing contacts of the current relay and the power direction, and the closing contact of the time switch is connected to the circuit of the circuit breaker of the corresponding side, the direction relay of the reverse sequence power, double-acting by number q q connections from the buses of a given voltage of the autotransformer, the current circuits of which are connected to current transformers of the corresponding voltage connections, and to the winding of the second time relay .J5 a circuit is connected consisting of contacts of the directional power relay of the connections oriented to the side of the buses, connected in parallel with each other and the closing contact of the reverse sequence power relay 20 'of the autotransformer oriented to the side of the buses, and connected in series with serially connected disconnecting contacts of the power relay, oriented towards the network, and the opening contact of the relay of direction of power of the reverse sequence of the autotrack on the transformer, which also has a two-way action, oriented towards the autotransformer, the make contact of the second time relay is connected in parallel with the contact of the first time switch, characterized in that, in order to improve performance in case of external short circuits, the make contacts of the power direction switch oriented towards the network, form parallel circuits of series-connected said contacts and windings of additionally introduced time relays according to the number of outgoing connections, which are connected to the closing contact of the current relay, the first closing contacts of the additional time relays are included in the trip circuit of their respective circuit breakers, and the second contacts form parallel circuits connected in series with the winding of the second time relay.