RU1809474C - Device for phase-by-phase control of switch - Google Patents

Abstract

Usage: high voltage switching technique. SUMMARY OF THE INVENTION: the device makes an advance phase-out with an average value of the absolute value of the aperiodic component of the current with respect to the other two phases. Moreover, in phases with a minimum and maximum value of the aperiodic component of the current, their values are averaged, which reduces the switching wear of the circuit breaker. 2 ill.

Description

The invention relates to electrical engineering, in particular to devices for controlling high-voltage switches of three-phase current and can be used in electrical installations of high voltage.

The aim of the invention is to increase the reliability of the operation of the circuit breaker when disconnecting a three-phase short circuit,

In FIG. 1 is a functional diagram of the device, where 1 is a power source, 2 is a switched circuit, 3 is a phase switch, 4 is a current transformer, 5 is a three-phase starting current relay, 6 is an active 2nd harmonic filter, 7 is a maxi selector, 8 - circuit for delayed shutdown of selected phases of the circuit breaker; 9 - relay protection of the switched circuit.

In FIG. 2 shows an example implementation of the proposed device for one phase,

where 10 are current circuits connected to similar inputs of other phases of the device, 11 is a rectifier for isolating the voltage proportional to the absolute value of the component of the second harmonic of the secondary current of this phase, 12 is a resistor for isolating the arithmetic mean value of three voltages proportional to the absolute values of the components the second harmonic of the secondary currents of three phases, 13 - from other phases of the maxi-mini selector, 14 - output relay of the maxi-mini-selector phase, 15 - delay element, 16 - to turn off the switch 3 of this phase, 17 - con an act of the starting relay 5, 18 - to the delay circuits of other phases, 19 - by relaying 9.

Thus, the phase inputs of the start relay 5 are connected to the current transformers 4 of the switched circuit 2, and the current phase outputs of this relay are connected to the inputs of the active filters 6. The outputs are acel

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active filters 6 through rectifiers 11 are connected to the inputs of maxi-mini-selector 7. At the output of maxi-mini-selector 7, output relays 14 (KL-1) are installed in each phase. The relay contacts 14- N.O. (KL-1.1) and N. 3. (KL-1.2) either directly or through a time delay element 15 connect the circuit 19 from the relay protection 9 to disconnect this phase 16 of the switch 3. At the same time N. 3. the contacts of the start relay 17 in normal mode bypass the circuit breaker delay circuit. The signal 19 from the relay protection 9 is also supplied to similar circuits of the other phases of the device - 18.

Referring to FIG. 2 diagram of an example that implements the proposed device, operates as follows. When a three-phase short circuit occurs in the switched circuit 2 in all three phases, aperiodic current components arise, which flow through the primary windings of current transformers 4 and magnetize the cores of these transformers. In this case, components of even harmonics appear in their secondary currents. The components of the second harmonic have the greatest magnitude. These components are separated in the device by means of active filters of the second harmonic 6 and rectifiers 11 are converted into voltages proportional to the absolute value of the second harmonic. The obtained voltages are fed to the inputs of the maxi-mini-selector 7, in which each of the three voltages is compared with the arithmetic mean value of these voltages allocated to the resistor 12. As a result, two of the three output relays 14 are triggered at the output of the maxi-mini-selector phases where extreme stresses are present. The contacts of these relays KL - 1.1 include a delay element 15 in the phase switching circuit of the switch 16 so that the signal from the relay protection 19 is delayed by the time determined by element 15. In the same phase where the component of the second harmonic has an average value of relay 14 not triggered, so the signal from the relay protection 19 passes to shutdown 16 without delay. When a three-phase short circuit occurs, at the same time as described above, the start relay 5 and its H are activated. 3. The contacts 17 in the delay circuit are opened, which triggers the trip delay circuit. In all other cases of unbalanced short circuits, the start relay does not trip and all phases of the circuit breaker trip without delay.

The implementation of the invention will improve the reliability of the function

tapping the circuit breaker by increasing the service life of the arcing contacts and reducing operating costs.

Claims (1)

SUMMARY OF THE INVENTION A phase-wise circuit-breaker control device comprising three terminals for connecting current transformers in three phases, three terminals for connecting units control of the phases of the circuit breaker and an output for connecting a relay protection output, characterized in that, in order to increase the reliability of the circuit breaker when tripping a three-phase short circuit, a three-phase starting relay with three phase inputs, three phase outputs and three starting outputs, three active second-harmonic filters with three inputs and three are introduced into the device outputs, a delay unit with three phase inputs, three start inputs, three control inputs and three phase outputs, each of the phase inputs of the start relay connected to the corresponding output for connecting a current transformer, each of these phase outputs of the start relay through an active second harmonic filter connected to the corresponding input of the maximine selector, the output of the specified maximine selector is connected to the corresponding phase inputs of the delay unit, the outputs of the specified delay unit are connected to corresponding outputs for connecting the phase control units of the switch, the starting outputs of the starting relay are connected to the corresponding starting inputs of the delay unit, the control inputs of the delay unit are connected to an output for connecting a relay protection output. 2 i2 ё Vetf. / 5