SU1246230A1 - Device for differential protection of converting installation - Google Patents

Abstract

The invention relates to converter equipment, namely to devices dp protection of valve-converting installations. The aim of the invention is to increase the sensitivity of the device. When energized or voltage recovered, after switching off an external short circuit, 14 p 12 0 occurs (L 4-16

Description

inrush current nama1 n1 chivan. A horcon, for example, 1, as in the case of a short wiring, triggers and sends a signal to the input of the element 15. The reed switch 5 operates. Since the magnetizing current through 0.01-0.012 s after it has appeared is close to the maximum5 time 10 i have

The invention relates to a TexiiiiKe converter, namely, protection devices for valve converter installations.

The aim of the invention is to increase the sensitivity of the device.

The drawing shows a diagram of a device for differential protection of a converter plant.

The device contains reed switches 1–4 with control windings and additional reed switches 5–7. Without windings, Wiston bridge of resistors 8 and magnetoresistor 9, time elements 10–12, HE element 13, memory element 14, AND element 15, a constant operational current source 16, an adjustable resistor 17J, an actuator 18, an alarm unit 19. The beginnings of the control windings of the reed switches 1-3 are connected to terminal 20 of the output of the Wiston Bridge, and the ends to the beginning of the control winding of the reed switch 4, the end of which is connected via an adjustable resistor. 17 to terminal 21 of the Whiston bridge ,.

The reed switches 1 and 5, 2 and 6, 3 and 7 are fixed in the magnetic field of the conductors 22-24 of the alternating current of the phases A, B, C of the converter plant consisting of the transformer 25 and the converter 26 to which the load 27 is connected The resistor is fixed in the magnetic field of the conductor 28 of the direct current of the converter 26. The opening contact of the reed switch 1 connects to the recording input of the memory element 14. tya Patching contact of the reed switch. 5 is connected to the input of the first element 10 time delay, the output of which is connected to the input of the element NO 13, the input of the second element 11 of the exposure

a delay of 0.01 seconds, sends a signal to the element IE 13. At the input of the element 15, the signal is removed and does not work. Thus, the sensitivity of the device is not limited by the surge current of the magnetization of the power transformer 25. 1 Il.

time - to the output of the memory element 14, the output of the second element 11 of the time delay is connected to the first input of the element 15 and the input of the third element 12 of the time delay, the output of the last time - to the reset input of the memory element 14 t., the output NOT 13 to the second input element And 15, the output of which is connected to the executive body 18, to which the contact of the reed switch 4 is connected, the other contact of which is connected to the contacts of the reed switches 1-3 and the alarm block 19 The contacts of the reed switches 5-7 are connected to the positive of the operating current source. Also connected are reed switches and logic elements for phases B and C.

The device works as follows (im image.

In the load of the converter, the installation of the magnetic flux Φ, created by the direct current 1у in the control winding of each of the reed switches, for example, the first and magnetic flux Φ, from the currents in the conductor 22 affects the reed switch 1 so that the latter is in its contacts are open, the recording input of memory element 14 of the signal is not received and the executive body 18 is not working.

This effect is ensured by the fact that Fu F -i-F + + Fz, where F is the magnetic flux, creating the amplitude value of the current Ij of the conductor load; F (p is the magnetic flux, under the action of which the calodyne from reed switches 1–3j Fz is triggered is the magnetic flux of the reserve, taking into account the discreteness of the change in Tu, the speed) of the current increase

the generator, the influence of the conductors of other phases on the reed switch, reinforced in the magnetic field of the phase under consideration IHI L n D t) i is the coefficient of the converter installation circuit, I ,, is the current of the current load of the transducer

spinner 1u is provided by varying the magnitude of the resistance of the magnet, the resistor 9, depending on the load current of the converter plant. The greater this current, the greater the resistance of the magnetoresistor and the greater the magnitude of the DC voltage at the output of the Wiston bridge (between terminals 20 and 21), and therefore, the current in the windings of reed switches 1-3.

, With a short circuit (short-circuit) in the converter 26, operating in the supreme mode, the current at least in one of the conductors 22-24; increases and decreases in the conductor 28, and the magnetic flux of the alternating current of the conductor, affecting, for example, a reed switch 1 in one of the half-wave current, is greater than the magnetic flux of the control winding current. As a result, the contacts of the reed switch 1, when they are outgoing, are closed, giving the signal to the recording input of the memory element 14, which triggers a time delay element 11 having a delay t of 0.011 s. Through t, the signal is fed to the input of element 15. The other input of element PI 15 receives a signal from the element HE 13, since the signal NO is not fed to the input of element 13 when the signal is due to the fact that the time delay element 10 has a delay tj 0.01 s and does not have time to work out during the closure of the contacts of the herk-5, which works and disappears into every half-wave of alternating current. The GSR current in the busbar 22 (23, 24), at which the reed switch 5 (6, 7) operates, can be chosen less than the rated current of the installation or slightly more (in the first case , theoretically very large). In either case, with a short circuit (short circuit), the time during which the contacts of the reed switch 5 are closed, tj 0.01. S, since the current half-wave t is 0.01 s. Thus, at the output of the element And 15, a signal appears and the executive authority turns off the installation. When turned on

j

0 5

0

2304

Research institutes under voltage or voltage recovery after switching off the external short circuit causes a surge of magnetizing current. The reed switch 1, as in the case of a short-circuit, triggers and sends a signal to the input of the element I 15. The reed switch 5 also operates. Since the magnetizing current is 0.01-0.012 s after it has occurred, it is close to the maximum (it has a period of one maximum), the time delay element 10 sends a signal to the element NOT 13, and at the input of the element 15, the signal is removed and behind; shrta does not work. At a time tj of 0 s (this time allows the actuator to be simplified) the time delay element 12 sends a signal to the reset input of memory element 14: t is chosen large t, since otherwise the signal supplied by time delay element 11 is element And 15, at the considered surge current of magnetization on the Vits before the signal from the other input of element 15 is removed, and the protection would work unnecessarily.

Thus, the sensitivity of the proposed device is not limited by the surge current of the power transformer, as is the case with other similar devices that do not use current transformers for obtaining information. It is safe to maintain, does not require the conversion unit to be taken out of work during scheduled inspections and can be used to protect only the transformer or the entire conversion unit.

Claims (1)

Invention Formula A device for differential protection of a converter plant, equipped with a transformer, containing an executive organ, reed switches with control windings, each of which is intended to place a corresponding alternating current phase on the high voltage side of the transformer of the installation transformer in a magnetic field, with a constant source operating current, controlling the reed switch and adjustable resistor, and the control windings of the reed switches through the winding of the controlling reed switch and adjust th resistor connected to the outputs of the block measurements, tl and h; o and e with the fact that, c. in order to increase the sensitivity of j to it for kai; that phase was introduced an additional reed switch, solenoid I., the element is NOT. the time element and the memory element, and the measurement unit is made in the form of a Wiston bridge, one of whose arms used a magnetoresistor designed to place the current-carrying current of the converter in the magnetic field, the remaining arms resistors, one diagocal of the wiston bridge was used as the outputs of the measuring unit j. and a friend of the diagonal of the bridge Wis: it is connected to the output of a constant operational current source, and in each phase an additional reed switch is intended to accommodate this alternating current in the magnetic field of the current conductor, the closing contact of the additional semiconductor reed switch through the first time delay element and the element is NOT connected to the first input of the And element whose output is connected to the input of the actuator, the disconnecting contact of the corresponding reed switch with the control winding is connected to the input recording a memory element, which is connected to the input of the second element of the time delay, the output of which is connected to the second input of the element And and to the input of the third element and time, the output of which is connected to the reset input of the memory element.