SU1471298A1 - Ac gate - Google Patents

Abstract

The invention relates to electrical engineering and can be used in industrial automation systems. The purpose of the invention is to increase the reliability of switching. The device contains control keys 6 and 7, thyristors 1 and 2, and delay element 13. The introduction of the control key 11 and the execution of a matching transformer 12 with two step-up windings ensure the switching of the power thyristors 1 and 2 at the moment when the current supplying the active-inductive load 3 passes through a zero value. 1 il.

Description

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The invention relates to electrical engineering and can be used in industrial automation systems.

The purpose of the invention is to increase the switching reliability by reducing the level of electromagnetic interference - due to the switching of the power thyristors at the moment the current supplying the active-inductive load passes through a zero value.

The drawing is a functional diagram of the AC key.

With a certain time delay, the value of which is approximately half of the period of the supply voltage, the delay element 13 triggers, which supplies the input of the third control key 11 to the start signal. As a result of this control key being turned on, the primary winding of the matching transformer 20

AC key contains two

thyristor 1 and 2, connected between torus 12, is connected to power output counter-parallel and sequences of thyristors 1 and 2, which are in conjunction with load 3 and power supply buses 4 and 5. Between the control electrodes and the anodes of the thyristors 1 and 2, the respective first and second control keys 6 and 7 are included, the inputs of which are connected to control buses 8 and 9, Control keys 6 and 7, depending on their performance, can be connected in series through each other. resistor 10,

The third control key 11 is connected via the primary winding according 25

locally with a load form a voltage divider. Since one of the thyristors at the time of switching of the matching transformer is open, the voltage drop on the primary winding does not usually exceed 2V, Then this voltage (working half) through the secondary windings of the matching transformer 12 and through diodes 14 and 15 is applied to the thyristors 1 and 2, alternately holding one of them in On mode, considering that. the load has an inductive current component, the switching of the thyristors will occur with a corresponding 1 m phase shift of the current by an angle from 0 to 90, t, e, practically without a cutoff of the sinusoid voltage of the supply voltage. The absence of a phase cut-off of the power supply completely eliminates interference in the power supply circuit and in the load.

Transformer 12 to the power terminals of thyristors 1 and 2, the control input of the third control key 11 is connected to the control buses 8 and 9 via delay elements 13. Secondary, winding matching transformer

are connected to the control inputs of thyristors 1 and 2 through the corresponding first and second diodes 14 and 15. To simplify the isolation of switched circuits. with control circuits, control keys can be executed on photo thyristors.

The key works as follows.

In the initial state, the alternating voltage is applied to the supply busbars 4 and 5, and there is no constant voltage on the buses B and 9 of the control. In this case, the keys 6 ,. Controls 7 and 11 are closed, the harmonized transformer is de-energized, as a result thyristors 1 and 2 are closed,

When applying a DC voltage jump to the control buses 8 and 9, one cc of the control keys 6 and 7 is activated, depending on the instantaneous polarity of the phase of the supply voltage. Turning on control key 6 or 7 causes the corresponding thyristor to turn on.

ras 1 and 2, and the switching of the first half-wave of the supply voltage can occur at an arbitrary phase value,

With a certain time delay, the value of which is approximately half of the period of the supply voltage, the delay element 13 triggers, which supplies the input of the third control key 11 to the on signal. As a result of this control key being switched on, the primary winding of the matching transformer

j of torus 12 is connected to the power pins of thyristors 1 and 2, which are

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locally with a load form a voltage divider. Since one of the thyristors at the time of switching of the matching transformer is open, the voltage drop on the primary winding does not usually exceed 2V, Then this voltage (working half) through the secondary windings of the matching transformer 12 and through diodes 14 and 15 is applied to the thyristors 1 and 2, alternately holding one of them in On mode, considering that. the load has an inductive current component, the switching of the thyristors will occur with a corresponding 1 m phase shift of the current by an angle from 0 to 90, t, e, practically without a cutoff of the sinusoid voltage of the supply voltage. The absence of a phase cut-off of the power supply completely eliminates interference in the power supply circuit and in the load.

Claims (1)

Invention Formula An alternating current key containing two anti-parallel thyristors, a first and second thyristor control keys, a matching transformer with two secondary control windings, a first and a second diode, and a delay element, characterized in that, in order to increase reliability, a third the control key, and the matching transformer is made with two higher windings, the primary winding of the matching transformer through the third control key is connected to the power electrodes of the thyristors, the secondary ovdapyayuschie windings are connected in antiphase with the thyristor control inputs through the corresponding first and second diodes, per314712984 the left and second control keys of the control keys are connected to the buses between the anode and the control electrical control, the input of the third key by the type of thyristors, respectively, the control is connected to the buses by the control inputs of the first and second controllers through the delay element.