SU1511859A1 - Device for controlling induction motor - Google Patents

Abstract

The invention is intended to automatically reverse an asynchronous electric motor in cases where equal durations of stopping the motor in extreme positions are required. The purpose of the invention is to increase the reliability of work. The device for controlling an induction motor contains windings 2 and 8 of magnetic actuators with contacts 6, 9 and 3, 12, respectively, contacts 4, 21 and 10, 22 of the first and second path switches, contacts 5, 11 and 23 of the control buttons, diode bridge 16, the time specifying the RC is the circuit 17, 18, the thyristor 19, the threshold element 20. The winding 2 and contacts 3-6 form a series circuit 1, and the winding 8 and contacts 9-12 are a series circuit 7. Connecting the leads of circuits 1 and 7 to the input terminal 15 bridges 16 and connecting terminals of pins 21 and 22 with common points of pins 9, 10 and 3, 4 s responsibly possible to reduce the number of contacts used. To reduce the current flowing through the contact elements, triacs are introduced. A resistor is included to limit the triac control current. 2 Il.

Description

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The invention relates to a pulse technique and is intended to automatically reverse an asynchronous electric motor in cases where equal durations of motor stops at the extreme positions are required.

The purpose of the invention is to increase the reliability of work by reducing the number of contacts used.

Figs 1 and 2 show circuit diagrams of the device for cases of small and large currents of power supply of magnetic actuators, respectively.

The device according to FIG. 1 contains the first circuit 1 of the winding 2 of the first magnetic circuit connected in series

When voltage is applied to busbars 13 and 14, if pins 4, 10, 21 and 22 are in the state shown in the drawing, windings 2 and 8 are cut. When the contacts 5 are closed along the circuit: bus I -, contacts 23, contacts 5, contacts 1 1, contacts 3, winding 2, bus 13, winding 2 is energized. The first switch starter turns on (;; its contacts 6 turn on, and contacts 9 open. The motor (not shown) starts to rotate in the forward direction. Due to the closure of contacts 6, the magnetic starter is held B1 off, and after opening contacts 5, Comte Kty 9 breaks the power circuit of winding 8, excluding simultaneous

the actuator, raz1 1ka} ack block contacts 70 triggered by both magnetic starters 3 of the second magnetic starter, the breaking contacts 4 of the first control switch and the closing contacts 5 of the first control button,

When under the action of a working body driven by an electric motor, contacts 4 are opened.

the shunted closing unit-terminal- 25 and the contacts 21 are closed, winding 2

cycles 6 of the first magnetic actuator, the second circuit 7 of the successive connecting windings 8 of the second magnetic actuator, the opening of the block to-contacts 9 of the first magnetic starter, 30 resistor 24, bridge 16, contacts 21,

l, the disconnecting contacts 10 of the second path switch and the closing contacts 11 of the second control button, shunted by the closure of block-contacts 9, the winding 8. passes the charge current of the capacitor 25 from which the single junction transistor 20 feeds.

cycles 12 of the second magnetic start-25 is significantly less than the current operated. The first terminals of circuits 1 and 7 are connected to the first supply bus 13, the second supply bus 14 is connected to the first output 15 of the first diagonal of the diode bridge 16, the second diagonal of which includes the time setting the CS circuit (resistor 17 and capacitor 18) and the thyristor 19 connected input to the output of the CS circuit through a threshold element (for example, a unijunction transistor) 20, and the second output of the first diagonal of the bridge 16 is connected to the connection point of the first terminals of the closing contacts 21 and 22 of the first and second path switches, the second terminals of circuits I and 7 are connected to 15 vodom bridge 16, a second terminal contact 21 connected to the common point 9 and the contacts 10, and second terminal contact 22 is connected to the common point contacts 3 and 4, contact 23 of the control buttons are used to disconnect the device.

The device of FIG. 1 operates as follows.

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of the magnetic starter. At the same time, through the resistor 17, the capacitor 18 starts charging. The CS circuit. When the capacitor 18 is charged before the voltage is unlocked by the single junction transistor 20, the latter is unlocked. The capacitor 18 through the opening transistor 20 is discharged to the input circuit of thyristor 45, causing it to be unlocked. The discharge of the capacitor 18 to the control electrode of the thyristor 19 is carried out for several (3-5) / half periods of the mains supply. During this time, the bridge 16 is maintained open and through it and in series with it the connected contacts 21 and 9 and the winding 8 current is flowing, causing the inclusion of a second magnetic starter,

This starter with its power clocks. Includes an electric motor for reverse rotation, Breaking contacts 3 eliminates the triggering of the magnetic starter with winding 2,

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When the action of the working body, driven by an electric motor, the contacts 4 are opened.

 and contacts 21 are closed, winding 2

the de-energized and starter with winding 2 is turned off. Its power contacts and contacts 6 open, contacts 9 close. At the same time through

contacts 9, the winding 8. flows the charge current of the capacitor 25, from which the unijunction transistor 20 is powered. The value of the charge current of the capacitor.

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of the magnetic starter. At the same time, through the resistor 17, the capacitor 18 starts charging. The CS circuit. When the capacitor 18 is charged before the voltage is unlocked by the single junction transistor 20, the latter is unlocked. The capacitor 18 through the opening transistor 20 is discharged to the input circuit of thyristor 19, causing it to be unlocked. The discharge of the capacitor 18 to the control electrode of the thyristor 19 is carried out for several (3-5) / half periods of the mains supply. During this time, the bridge 16 is maintained open and through it and in series with it the connected contacts 21 and 9 and the winding 8 flows current, causing the inclusion of a second magnetic starter,

This starter with its power cocks. Includes an electric motor for reverse rotation. Breaking the contacts 3 prevents the magnetic starter with winding 2 from triggered.

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With the closure of contacts 22 and the opening of contacts 10, M1,1, i.e. when the second path switch is turned on in the same way as described, the magnetic starter with winding 8 is de-energized, and winding 2 of the first magnetic starter is connected to supply buses 13 and 14 via bridge 16, closing contacts 22 and 3. After a time delay determined by the charge time of the capacitor 18, the thyristor 19 is unlocked, providing the excitation of the winding 2,

Hereinafter, the described work processes are repeated,

To reduce the current flowing through the contact elements, triacs 26 and 27 can be used (Fig. 2). DTD limiting the currents flowing through the control electrodes of the triacs 26 and 27, includes a resistor 28,

Claims (1)

The device of FIG. 2 operates similarly to the device for controlling the induction motor of FIG. 1, except that it initially provides for switching on, corresponding triacs, and then exciting the connected windings 2 and 8 of the magnetic starters in series with it. Formula invented and 1, the Device dp control of asynchronous electric motor, containing-; first circuit of the successively connected windings of the first magnetic starter, the opening contacts of the second magnetic starter, the opening contacts of the first track switch, the switch and the closing contacts of the first control button, shunted by the closing contacts of the first magnetic starter, the second chain of series connected Lambotki second magnetic starter, tripping the auxiliary contacts of the first magnetic starter, tripping contacts of the second path switch 8596 and the closing contacts of the second control button, which are shrouded by the closing contacts of the second magnetic actuator, the first terminals of the first and second specified serial circuits are connected to the first supply bus, the second feed bus is connected to the first terminal of the first diagonal Q of the diode bridge, the second diagonal of which the time specifies the KS circuit and the thyristor, connected by the input to the output, the time that sets the pi through the threshold element, and the second 5, the output of the first diagonal of the diode bridge is connected to the connection point of the first conclusions of the closing contacts of the first and second path switches, characterized by 0, in order to increase the reliability of operation, the second pins of the first and second serial circuits are connected to the first pins of the first diagonal of the diode bridge, the second pins of the first contacts of the first junction switch are connected to the common point of the opening contacts of the first magnetic starter switch, and the second pin is closing The contacts of the second track switch are connected to the common point of the plug-in contact block of the second magnetic starter and the disconnecting contacts of the first track switch, 2, the device according to claim 1, about tl and often that contains the first and second triacs, the anodes of which are connected to the second supply 0, the cathode – control electrode junctions are included in the first and second successive circuits, respectively, between the winding pins of one magnetic starter and the opening contact block of the other magnetic starter, and a resistor is connected to the first diagonal of the diode bridge to the first diode bridge. five vO gin to S9 CSI