SU1571720A1 - Arc protection of factory-assembled switch-gear - Google Patents

Abstract

The invention relates to electric power industry and is intended for use as a protection of cells of a complete switchgear (KRU) against arc faults. The purpose of the invention is to improve noise immunity by continuously monitoring the state of illumination of the cell of the switchgear cell. The goal is achieved by controlling the flow of current and burning the arc in every half of the period of the industrial frequency during the entire emergency state of the electrical installation. 2 Il.

Description

The invention relates to power engineering and is intended to perform relay protection of a complete switchgear against arc damage.

The purpose of the invention is to improve noise immunity by continuously monitoring the illumination state of the cell compartment.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 - curves of currents and voltages on the elements of the device (Arabic indices correspond to the numbers of the elements).

The device includes an intermediate transformer 1, connected to an input cell current transformer chain and loaded onto a chain of counter-connected Zener diodes 2, a multiphase rectifying bridge 3 of photodiodes located in the switchgear cells loaded onto. a resistor 4, and the output of the bridge is connected to a series-connected logic circuit NOT 5, integrator 6, threshold element 7, output organ 8.

To provide a continuous output signal, threshold element 1 has a delay of 12-15 ms for return.

Consider the operation of the device in normal mode and with an arc short circuit in the cell.

In normal mode, the current in the current transformer of the input cell in the intermediate transformer 1 flows. The output voltage of the intermediate transformer is limited by the zener diodes 2 and is rectified by the rectifier 3. The voltage on the resistor 4 has no dead time, and the output voltages on all other elements including the output body 8 are missing.

In case of arc damage in one of the cells of a candle, the arc radiation enters the photodiode of the corresponding compartment. The resistance of the reverse branch of the illuminated photodiode drops sharply, which leads to the shunting of the resistor 4 in the corresponding half-period. This leads to the appearance of dead-end pauses at the input of the element NOT 4. At

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The output of this element at these times will be signals. At the same time, the voltage at the output of the integrator 6 increases, and when the specified level UCp is reached, the threshold element 7 is triggered.

After that, with a small delay (about 3 ms), the output organ is triggered and sends a command to turn off the input cell switch.

Claims (1)

Invention Formula The arc protection of the complete switchgear, containing a current transducer with an output stabilizer, designed to be connected to the input cell current sensor, a photoelectric transducer installed in the cell compartments, a variable resistor, one output which is connected to one of the outputs of the photovoltaic converter, a series-connected threshold element and an output organ, characterized in that increasing noise immunity by continuously monitoring the illumination state of the cell compartment; the series-connected element NOT and the integrator are additionally introduced, while the photovoltage transducer made in the form of a multi-shoulder rectifying bridge assembled from photodiodes is connected to the other output of the second variable AC terminal. resistor and the first input element is NOT, the second input of which is connected to the adjusting input of the variable resistor, and the integrator output is connected to the input of the threshold element.