SU1192014A1 - Generator of modulator oscillations having non-industrial frequency in zero-phase sequence current circuits - Google Patents

Abstract

MODULATED MODULATED VIBRATIONS OF THE UNFESSIONAL FREQUENCY IN CIRCUITS OF ZERO SEQUENCE CURRENTS, containing a zero-sequence voltage transformer, to the secondary winding of which, through the thyristor switch, a load resistor, control inputs of the thyristor switch, connected to the main partitions, connected to the main partitions, the control inputs of the thyristor switch; that, in order to increase the reliability of operation, to the output of the voltage transformer of the zero sequence C are connected again data formers of standard pulses for each (each second half-period of zero-sequence voltage, whose codes are connected to the inputs of the newly introduced element OR and the inputs of a frequency divider whose output is connected to the first input of the newly introduced element AND, to the second input of which is connected the output the element OR, the output of the element 9 AND is connected to the input of the driver of control pulses.

Description

1 The invention relates to electrical engineering, in particular to frequency converters of electrical signals, as well as devices for protection against earth faults in networks with any design of an insulated neutral. The aim of the invention is to increase the reliability of operation. FIG. 1 is a block diagram. the proposed generator; in fig. 2 is a temporary voltage chart of the generator block circuit. A generator of modulated oscillations of a non-reduced frequency in a zero-sequence circuit consists of a zero-sequence voltage transformer (TNNP) 1 .. A load resistor 2 is connected to the secondary winding of the transformer via a thyristor switch 3. Moreover, the switch can be performed either on a symmetrical thyristor, or on two parallel-parallel thyristors. The switch control system consists of standard pulse formers 4, including a sensitive zero-organ and an element that generates a pulse of a given duration, connected to the secondary terminals of the TNNP 1, the output of one standard pulse generator is connected to one combined input of the logic element OR 5 and frequency divider 65 and the output of the other driver - with another combined output of the same elements; The outputs of the logic element OR 5 and the frequency divider are connected to the inputs of the logic element AND 7, the output of which is connected to the control electrodes of the switch thyristors through the driver of the control pulses 8. The driver of the control pulses can be implemented, for example, in the form of a power amplifier (thyristor key) with a relay at the output, the closing contact of which is included between the control electrodes of the thyristors of the switch 3. Also for the control of the thyristor switch can be used thyristor optocouplers, including nnye on executive yield. When a symmetric thyristor is used as a switch 3, the load of the driver 8 will be 14 2 to serve as the triac control transition itself. Frequency divider 6 consists of two flip-flops, the first of which is an asynchronous RS-flip-flop 9 with split inputs, and the second is a counting JK-flip-flop 10, Except. This, the frequency divider 6 can be made in the form of a ring counter, a capacitive storage device with a threshold for 1 / auch and others. The standard pulse generator 4 can be made on the basis of a delay element (one-shot). Ge} 1rarator works as follows. As can be seen from the timing diagram in FIG. 2, when a ground fault (t) occurs in the network, the formers of standard pulses 4 convert the zero-sequence voltage signals (3 Ujj) arriving at their inputs into rectangular pulses of a given duration (04) fixing the leading edge to zero. input signal, with one standard pulse shaper converts the positive half-periods of the input signal (U) in the manner described, and the other - negative (U, -). Pulse signals from the shaper outputs, shifted by 180, are fed to the combined inputs of the logic element OR 5 and frequency divider 6, Frequency Divider 6 recalculates (dividing) the frequency of the following pulses into four (11) Pulse signals from the outputs of the OR element 5 (Ur) and frequency divider 6 (Ug) are fed to the inputs of logic unit 7, the output of which forms a signal (U), which through the driver of control pulses 8 provides the switched on state of the thyristor switch 3 for a duration of awns one period of the zero sequence voltage. Thus, switch 3 closes the secondary winding of the TNN I to the current-limiting resistance 2 every odd period of zero sequence voltage, thus changing the current value in the primary winding of TNNP 1, thereby modulating the control current in the zero-sequence current circuit.

31

With this principle of operation, the switch is in the open state during the entire period of the zero-sequence current, thus achieving symmetrical modulation of the control current. Thus, since the current flowing through

1920144

TNNP 1, is symmetric with respect to the zero value, therefore, the constant component of the current is equal to; zero and eliminates all even harmonic components. All this allows to increase the reliability of the control current overlay system.

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Claims (1)

MODULATED GENERATOR VIBRATIONS OF INDUSTRIAL FREQUENCY IN CHAINS OF ZERO-SEQUENCE CURRENTS, containing a zero-sequence voltage transformer, to the secondary winding of which a load resistor is connected through the thyristor switch, the control inputs of the thyristor switch are connected to the output of the control pulse shaper, and also a frequency divider that reliability of operation, the newly introduced shapers of standard and pulses for each half-cycle of the zero sequence voltage, the inputs of which are connected to the inputs of the newly introduced OR element and to the inputs of the frequency divider, the output of which is connected to the first input of the newly introduced AND element, to the second input of which the output of the OR element is connected, the output of the And element is connected to the input of the - -SU .. „1192014 L - ” ¹ 4“ ---- ^L - * g * - fig ι