SU1582270A1 - Method of arc protection of factory-assembled switchgear - Google Patents

Abstract

The invention relates to the field of electrical engineering and is intended for the relay protection of complete switchgears against arc short circuits in them. The purpose of the invention is to increase reliability, sensitivity and selectivity. This is achieved by controlling the phase relationships between the second harmonic components of the signals, which are proportional to the light emitted by the arc and the rectified current of the input cell. 2 Il.

Description

The invention relates to electrical engineering and is intended for the relay protection of switchgear-type switchgears of the type KRU and KRUN against short circuits (CC) inside the cells of switchgear data, accompanied by an open arc.

The aim of the invention is to increase the reliability, sensitivity and selectivity by controlling the phase relationships between the second harmonic components of the light and current signals.

FIG. 1 shows a block diagram of a device implementing the method; in fig. 2 - timing diagrams for short-circuit in one of the cells.

The arc protection device of complete switchgear 1, consisting of cells (in this case 6 cells are shown), in the input cell of which the input

switch 2 and current transformer 3, contains photo sensors 4-4 installed in each cell, band-pass filters 10-16, tuned to the second harmonic component, intermediate current transformer 17, rectifier 18, phase comparison circuits 19-24, output units 25-30, scheme OR 31, delay element 32.

The phase comparison circuit 19-24 can be implemented on any principle.

The device works as follows.

In normal operation of the switchgear (in load mode), the output of the photosensors 4–9 and the bandpass filters 10–15 output signal is zero, and at the output of the bandpass filter 16, the signal level is determined by the load current. In this case, on the second run of the phase comparison circuit, the signal

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is equal to zero, and therefore the signal is also zero at their output, and, consequently, all other elements of the device are in an inoperative state and the signals at their output are zero.

Damage accompanied by an arc, for example, in the cell where the photosensor 5 is installed, leads to an increase in light emission in this cell and the appearance of a signal at the output of the photosensor 5 and band pass filter 11, as well as at both inputs of the comparison circuit in phase 20, which leads to the output signal is released at its output and the trip signal is generated by the output body 26. In the event that an alarm cannot be localized, after the time delay of the delay element 32, a signal is given to turn off the input switch 2.

In this case, the light emission of the arc is modulated by the second harmonic frequency of the protected network and practically coincides in phase with the circuit current with the arc. In FIG. Figure 2 shows the signal generation sequence (the signal indices correspond to the numbers of the device elements). U characters

// i. v

and Uio denote the voltage at the output of the sign of the signs of the monitored quantities and the integrator, which are the constituent elements of the phase comparison circuit, and IL, the level of the formation of rectangular pulses from sinusoidal signals, which is determined by the magnitude of possible unbalance in the circuit. The tripping voltage Ucp determines the width of the zone of operation of the comparison circuit in phase. The signal U7t is with some delay in relation to the signal Ui6, which is necessary for the detuning from various kinds of interference.

In case of a fault outside the switchgear, the device is in an unworked state, since in this case there is no light emission inside the cells representing the closed volume.

The device is in an unworked state even with a visual inspection of the switchgear switchgear (H) cells, as in this case

the light emitted by sunlight or lighting devices has a constant spectrum, and therefore, at the output of the band-pass filters 10-15, the signal is close to zero, which ensures that the comparison circuit in phase 19-24 does not work.

The proposed device also does not work when the temperature rises. This is ensured by the introduction of bandpass filters that do not allow the constant component of the signal to pass.

. Such an embodiment of the device makes it possible to refuse the brake photosensor, which simplifies it.

Thus, the method of performing arc protection and the device that implements it, allows you to build protection against arc faults in complete switchgears with higher reliability (by controlling the two parameters of the arc), to increase sensitivity by reducing the time level, one by one and at another controlled value, to ensure selective shutdown, even in the presence of interference signals.

Claims (1)

Invention Formula The arc protection method of complete distribution devices, in which the luminous flux in each cell of the complete distribution device is monitored, is converted into an electrical signal, from which a damaged cell disconnect signal is formed, characterized in that, in order to improve reliability, sensitivity and selectivity, the current of the input cell into the voltage, rectifying the voltage obtained, isolating the second harmonic component of this signal, the phase of which is compared phase signal proportional to the second harmonic component of the luminous flux of each cell, the coincidence of the phase signal to generate a trip switch damaged cells without time delay and Disconnect signal input switch with a time delay l / vy A a l V V 1 LL / wfe vshesg. on Off .Lae / a. 2g g Figure 1 and -UP, Uw 4 „OmjL chain JfaMW. Utto Uu Figg