SU1651339A1 - Device for power transmission line protection from overcurrents - Google Patents

Abstract

The invention relates to relay protection and can be used in overcurrent protection circuits having a selective time delay. The purpose of the invention is to increase the speed of protection and selectivity. For this, the acceleration of the overcurrent protection (MTS) is carried out by automatically reducing the time delay of the selective MTS to zero due to the absence of the load current before the moment of short circuit. 1 hp f-ly, 2 ill.

Description

The invention relates to the field of electrical engineering, in particular, to relay protection of a power line, and is intended for use in overcurrent protection circuits (MTZ) of lines with long time exposures.

The purpose of the invention is to increase the speed of protection and selectivity.

FIG. 1 shows a circuit for connecting the overcurrent overload line to the line — FIG. 2 shows the operational overcurrent circuit.

The device for overcurrent protection of power line 1 contains on the side of the supply switch 2 the first current relay 3 with the closing contact 4, the relay 5 time with contact 6, the closing with delayed response time, and with the instant contact 7, the intermediate acceleration relay 8 with the closing contact 9, with retarding delay, auxiliary contact 10 of the supply switch 2 and a shut-off electromagnet 11, the closing contact 4

current relay 3 is connected to the winding of the time relay 5, contact 6, closing with a delay time to actuation, relay 5 time through the blocking contact 10 of the supply switch 2 are connected in series with the shutdown electromagnet 11 and in parallel with serially connected instantaneous contact 7 of the relay 5 time and closing pin 9, having a slowdown in the return of the intermediate relay 8 acceleration. In addition, the device contains a second current relay 12 for controlling the presence of a load on the protected line 1 or a disconnecting block contact 13 of the receiving switch 14, while the coil of the intermediate acceleration relay 8 is connected to the disconnecting contact 15 of the current relay 12 controlling the presence of a load on the protected line or disconnecting the contact pin 13 of the receiving switch 14.

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The device works as follows.

If there is no load before the short circuit (short circuit) on line 1 or switch 14 is disconnected, then contacts 15 of relay 3 or the auxiliary contact 13 of switch 14 in the winding circuit of the acceleration relay 8 are closed, and therefore, contact 9 of the acceleration relay 8 is closed.

At the moment of the fault, relay 3 triggers and closes its contact 4 in the time relay circuit 5, which triggers and closes the instant contact, forming a tripping circuit from the series-connected contacts 7.9 and 10. At the same time, contact 6 of the relay 5 time closes with a time delay shunted.

If there was a load in front of the short-circuit on the line or the switch 14 is turned on, then the contacts 15 and 13 are open and the acceleration relay 8 is de-energized, and its contact 9 is open. Therefore, in case of short circuit, the switch-off of switch 2 will occur with a time delay along the circuit: pin 6, time relay 5, pin 10.

Claims (2)

1. A device for maximum protection of a power line with a power supply and with a receiving switch, equipped with opening block contacts, containing on the side of the power switch of the line a first current relay with a closing contact, a time relay with a contact closing with a delayed response time and an instantaneous closing contact, an intermediate acceleration relay with a closing contact decelerating to return, and a shut-off electromagnet, the closing contact of the current relay connected to the winding of the time relay, a time relay contact closing with a time delay to actuation, through the auxiliary contact of the supply switch is connected in series with the shutdown electromagnet and in parallel with serially connected instantaneous closing contact of the relay in A slow-down contact and a closing contact to return an intermediate acceleration relay, characterized in that, in order to improve speed, the device contains a second current relay to control the presence of a load on the protected line, while the winding of the intermediate acceleration relay is connected to the disconnecting contact of the current control of the load presence on the protected line. 2. Device n.t. characterized in that, in order to increase the selectivity, the disconnecting block contact of the receiving switch is connected in series with the coil of the intermediate acceleration relay. - OGL V1 hp Substation .N1 U2 Nd | 1 73 i L. one 1