SU589660A1 - Device for protection of step-down transformer with isolated neutral wire in substation without switches on higher voltage side - Google Patents

Description

control unit and in the course of the control unit, and into the control unit circuit.

The drawing schematically shows the proposed device.

The step-down transformer 1 is connected through the separator 2 with the disconnecting unit 3 to the power line 4 The short circuit breaker 5 with the plug-in unit 6 is inserted between the transformer 1 and the separator 2. The input of the control unit is cheap. The bodies and the separator 7 are connected to the external relays; 8 transformers are sewn up. The code of this block is connected to block 3 by means of the blocking relay 9, the other output of this block is connected to block 6 of the short circuit breaker. The neutral transformer 1 is grounded through a resistor 10, in parallel to which the valve discharger 11 is connected. A resistor 11 is connected to a current transformer 12, the output of KOTOporq is connected to a time relay 13, the outputs of relay 13 are connected to the inputs of a control unit 7 and a lock relay 9.

When an asymmetrical mode occurs, as a result of phase breaks and short circuits to earth, a current arises in the resistor 10, causing your time relay 13 to trip if its value is greater than the specified value. Timer 13 triggered at current in the primary resistor circuit

0.5-1.5 A and starts up the control unit 7, which turns on a short circuit 6 / if the current in the resistance circuit V is more than a predetermined time of 2-5 seconds. One “new time relay 13 with 11yyosh.yo

the blocking relay 9 discharges the circuit, connecting the control unit 7 to the input of the separator 2 disconnecting unit 3 This leads to the disconnection of the power line 4 due to unsuccessful automatic switching on of the line, as the automatic reclosing unit did not separate the transformer from the lingg short goats gobble up,

The delay of the short-circuit switch on for 2-5 seconds makes it impossible for it to operate when there is an inconsistency.

short-circuits {in the specified time of short-circuits in the electrical network

eliminated).

The application of the proposed device also eliminates the need for pre-grounding the neutral of the underdog transformer during scheduled switching in the supply voltage network.

Claims (3)

1. USSR author's certificate, № 470888, cl. H O2 H 7/04, 1974. 2. On protection of 110 kV transformers with incomplete nvoltion of neutral, Electrical Standards, No. 11, 1964. 3.IT F Gogichaishvili. Under the station without switches on higher voltage, M. Higher School, 1965, p. 115-121 ..