SU1203622A1 - Voltage relay - Google Patents

Description

The invention relates to electrical engineering and is intended for switching consumers in autonomous electric power systems (EPS) from the main supply network i to the backup one when the network voltage deviates from the set values.

The purpose of the invention is to increase the reliability of the relay operation by reducing the likelihood of triggering with distortions of the monitored voltage curve and the duration of the output pulses of the threshold unit, not exceeding the single-vibration settings.

Figure 1 shows the voltage relay; figure 2 - cyclogram, Ma operation of the device.

The voltage relay contains a threshold unit 1, the first one-shot 2 and the summing block 3 made as an OR element, the first input of which is connected to the output of the first one-shot 2. In the device there are a second one-shot 4, element 5, repeater 6 the front of the input signal and two-channel switch 7, the input connected to the output of the threshold unit 1, and the first and second outputs - with the inputs of the first 2 and second 4 single-oscillators, respectively. The output of the second one-shot 4 is connected to the second input of the summing block OR 3, the inverting output of which is connected to. the first input element And 5. while the second input of the latter through the repeater 6 is connected to the output of the threshold block J, and the output to the relay output.

The repeater 6 is made on the third one of the selector 8 and element 9 MOD-2, the first input of which is connected to the output of the third one-shot 8, the second input - to the input of the third single vibrator 8 and the output of the threshold unit 1, and the output to the second input of the And 5 element Element 9 LND-2 realizes at its output a logic function of the input signals of the form, X:, Xg (nonequivalence, ICK iO SHOSHEE SHSh) and is made with a response delay exceeding the response delay of the one-shot 8.

The voltage relay operates in the following manner.

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A controlled voltage U is supplied to the input of the threshold unit 1 (for three-phase AC networks from a voltage transformer 5 through a three-phase Larionov h rectifier bridge. When the input signal decreases (increases) below (above) the threshold unit 1, which can occur during dips (emitted 10) or when the voltage waveform is distorted, a signal corresponding to logical 1 appears at the output of the threshold unit 1. The pulse duration (Fig. 2a) corresponds to the time of the existence of a low (high) voltage by compared with the selected installation.

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0

From the output of the threshold unit 1, a sequence of pulses arrives

through the switch 7 to the inputs of the single vibrators 2 and 4, which are alternately switched on by the leading edge of the corresponding pulse (Fig. 2a, b,

5 c). The output signals of the one-shot arrives at the input of the summing block 3 AND W. From the inverting output of the last signal arrives (FIG. 2d) at the first input element I 5. To the second input of which the signal comes from the output of element 9 MOD-2. The signal 1 at the output of element 9 appears with a delay of A.t t-i - t, (fig. 2e) after the signal 1 arrives at the input of the repeater 6 from the output

- threshold block 1. Works

element 5 (fig.2e), the relay output gives a signal about the deviation of the monitored voltage from the set value. The time At, the delayed response of the repeater 6 is necessary to exclude false relays on the leading edges of the output pulses of the threshold bore 1,

The invention allows to receive a signal at the relay output, revealing a decrease (increase) in the voltage in the power system only after a predetermined time / it, i.e. steady dips (voltage surges), the duration of which is larger than the set time of one-shot. The relay does not react to short-term voltage changes, for example, related to interference from the t -istor units. The proposed relay is more reliable than the known one, since excluding

312036224

No false alarms in case of distortion. The operation of the voltage relay checked the forms of the monitored voltage on the prototypes in the stands, which, in general, allows increasing the work of the electric power industry on the operation of the EPS.

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Claims (2)

1. VOLTAGE RELAY, containing a threshold unit, the first ONE-1: a rotor and a summing unit made in the form of an OR element, the first input of which is connected to the output of the first one-shot, characterized in that, in order to increase the reliability of operation by reducing the likelihood of operation when the shape distortions the curve of the monitored voltage and the duration of the output pulses of the threshold block, not exceeding the settings of the one-shot, a second one-shot, the element And, a repeater with a delayed response to the front window is introduced into it the input signal and a two-channel switch connected to the output of the threshold block by the input, the first and second outputs are connected to the inputs of the first and second one-shots, respectively, the output of the second one-shot is connected to the second input of the summing block, the inverting output of which is connected to the first input of the And element, while the second input of the latter through a repeater is connected to the output of the threshold unit, and the output to the output of the relay. 2. The relay according to claim 1, characterized in that the repeater is made on the third one-shot and the MOD-2 element, the first input of which is connected to the output of the third one-shot, the second input - to the input of the third one-shot and the output of the threshold unit, and the output - from the second input element I. figure 1