SU1524125A1 - Directional relay for earth fault protection - Google Patents

Abstract

The invention is intended to protect power lines. The aim of the invention is to increase the selectivity of protection. In the case of single-phase earth fault in the network, control windings 7 and 10 of the reed switch 6 will be supplied with signals from blocks 1 and 8 of the current measurement of the zero sequence of the monitored and reference connections, respectively. When closed outside the protection zone, the signals from blocks 1 and 8 coincide in phase and are applied to the counter-connected control windings 7 and 10, as a result of which the reed switch does not work. When ground to earth in the protection zone, the signals from blocks 1 and 8 have different polarity, and a reed switch 6 is triggered in the output circuit 3, which triggers when there is a zero-sequence voltage signal at the input of power supply 4. 1 sludge.

Description

(OrVM)

The invention relates to devices for protection against earth faults, in particular for the protection of power lines in the mining industry.

The aim of the invention is to increase the selectivity of protection,

The drawing shows a schematic diagram of a directional relay for protection against earth faults.

The device contains a unit 1 for measuring the current of the zero sequence of the monitored signal with a rectifier 2, an output unit 3, a unit 4-Power, a phase-sensitive organ 5, a closing reed switch 6, a control coil (winding) 7 of the reed switch is connected to the output of the zero-sequence current measuring unit, additional - a lower unit 8 for measuring the current of the zero-sequence of the reference signal with a rectifier 9, the output of which includes a second control coil (10) of the reed switch. The zero-sequence current measurement unit contains a discharge voltage 11, resistors 12-14, zener diodes 15, inductor 16, capacitors 17 and 18, power supply 4 contains rectifier 19, capacitor 20, resistor 21.

To obtain the reference signal of the zero-sequence current, it is possible to use a short length of cable line, passed through the magnetic core window and connected via a switch to the common buses, capacitors connected to a star with a zero point are connected to the end of the line

The device works as follows.

During normal network operation, circuit elements in the zero-current measurement unit of the monitored signal and the zero-sequence current measurement unit of the reference signal are in a de-energized state.

In the case of a single-phase earth fault in the network, the control winding 7 of the reed switch 6 is supplied with a current signal during each positive half period. The trigger threshold of the reed switch 6 is selected such that in the absence of a signal in one of the control windings 7 and 10 it does not work. With a single-phase short to earth

revenge from the additional block 8, the current of the zero-sequence of the reference signal is received. The signal is received at the yr} winding winding 10. Depending on the place of recording, the signals arriving at the control circuits of 7 ji 10 can cope with the phage or differ method 180. If a single-phase short circuit occurs outside the protection zone (. at another controlled connection, the signal from the zero-sequence current measuring unit to the control winding 7 coincides in phase with the signal supplied to the control winding 10 s of the zero current measuring unit of the reference signal The control windings 7 and 10 each turn on each other, in connection with the circuit their magnetic fluxes demagnetize each other, the reed contact does not work.If the single-phase circuit: occurred on the ground in the protection zone (in a controlled connection) , then the signal from the current measurement unit of the null ISOT: the sequence of controlled connection to the control winding 7 and the signal from the zero-sequence current measurement unit on the control winding 10 are shifted relative to each other and ISO (different polarity). The resulting magnet-Hbii i flux is amplified due to the counter-coupling of the windings. The reed switch triggers and closes the LU-PI of the output coil. The output organ is triggered, since at a single-phase circuit, a zero sequence voltage is applied to the input of the power supply unit. During the subsequent negative half-cycle of the zero-sequence current, in undamaged connections, the contacts are open, since on the control of windings 7 and 10 are signals from the zero-sequence current measuring unit of the monitored signal and the additional measuring unit mp, -: g: the signal is received in the same phase and the signal from block 8 is not passed by the rectifier 9.

In the case of unbalance currents that occur when starting powerful motors in the connection, the current signal is fed only to the control winding 7 from the measuring unit

i

the zero-sequence current of the controlled connection, which is not enough to trigger the gerkun 6.

In block nzmer | Current current zero field researcher. A discharge generator P, resistor 12, and stabil ibi 15 are used for current limiting: from the three circuits; ::: Jamkanipk to ground, resistor 13 for reguhgirovanii protection protection set point, coil 16 inductance, capacitor 17 for extracting a signal with a frequency of 50 Hz, capacitor 18, resistor 14 for increasing the sensitivity of protection and prevent it. false action in transients.

In order to increase the sensitivity of the relay of the reed switch and the reed switch itself, D armor carbonyl heart1: K is placed, due to which the actuation power decreases.

D.P increase h / vstvennosti possible also.; the inclusion in the output circuits of blocks 1 and 3 of amplifiers made on transistors 22 and 23 in the circuit whose circuit includes cooTiU .TcTBcHHo windings 7 and 10,

The proposed device allows jiof to be enhanced. toperity of operation;: Protection and achieve simplified {circuit settings in the production

524125,

conditions by comparing one type of signals from two zero-sequence current transformers.

In this case, the supply voltage to the circuit is supplied only if there is a single-phase ground in the network.

Claims (1)

Invention Formula Directional protection against earth faults containing current and voltage zero voltage measuring units, output organ, power supply unit, phase sensitive organ made in the form of a circuit consisting of output organ coil in series and make contact contacts of the reed switch connected to the output of the power supply unit reed switch control coil Included at the output of a zero-sequence current measurement unit, characterized in that, in order to increase the selectivity of protection, In addition, a zero-sequence current measurement unit of the reference signal, the output of which the newly introduced second control unit coil of the reed switch is turned on, is turned on counter to the first control coil, and the power supply unit is connected to the output of the voltage measurement unit of the zero voltage. Compiled by O. Muratov Editor G. G. «R | -R Tehred M.Hodanich Proofreader T.Lonchakch) va Zak- 70S2 / 54 Circulation 608 ZSHCHIN State Committee for Inventions and Discoveries prn GKIT USSR 1130) 5, Moscow, F-35, Raushsk nab. 4/5 Subscription