SU1304156A1 - Device for starting induction electric motor - Google Patents

Abstract

The invention relates to electrical engineering and can be used in electric drives of various technological installations in which electrical power outages are unacceptable as a result of a brief interruption of power supply. The aim of the invention is to increase reliability. This goal is achieved by lowering the level of operation of the device and increasing the stability of the time delay during the recovery period of the supply voltage. The device contains a magnetic starter, the control coil 1 of which is connected to the power source through the series 2 Stop button and the Start button 3. Parallel to the Start 3 button, the closing contact 4 of the magnetic starter and the symmetrical thyristor 29 are connected, which is controlled through the transistor 15 by the pulse generator 30. The pulses for turning on the symmetric thyristor 29 are not served in two cases: if the magnetic starter was turned off with the Stop 2 button and if long dead time is longer than the time delay setting. The time delay for switching on the magnetic starter is specified by the time constant of the capacitor circuit 1 7 and the resistor 16. to (Л S from about 4 kV SP 05 15

Description

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The invention relates to electrical engineering and can be used in electric drives of various technological installations in which electrical power outages are unacceptable as a result of a short interruption of power supply.

The purpose of the invention is to increase reliability.

The drawing shows a schematic diagram of the device.

The device for starting an asynchronous motor contains a magnetic starter with a coil 1, one output of which through a serially connected button 2 Stop and a button 3 Starting bypassing the closing contact 4 of the magnetic starter, is provided with a first clamp 5 for connecting a source of Peteran to another, another OU The OD of the coil 1 of the magnetic starter is provided with a second clamp 6 for connecting to the Other terminal of the power source and to the series-connected first resistor 7, first diode 8 and dynistor 9, the first capacitor 10 tipped with the first Zener diode 11, the terminals of the second resistor 12 are connected in parallel to the second capacitor 13 and the second zener diode 14, the transistor 15, the third resistor 16, the third capacitor 17, the second, third, quarter and fifth diodes 18-21, the fourth, fifth, sixth, seventh and eighth resistors 22-26, third and fourth zener diodes 27 and 28, triac 29 and pulse generator 30 with two inputs 31 and 32 positive and common pins 33 and 34, the terminals of resistor 16 are connected in parallel to capacitor 17 and zener diode 27 whose anode is connected to the anode of the diode 18, cat D which through a resistor 22 is connected to the anode of the dynistor 9 and with the cathode of diode 19 the anode of which is connected to the anode of the Zener diode 14, the cathode of which is connected to the input 32 of the pulse generator 30 and through the resistor 23 to the cathode of the diode 20 which is connected to to the power supply, parallel to the Start button 3, a triac 29 is connected, the control electrode of which is connected to the emitter of the transistor 15, the collector of which is connected to the output 34 of the pulse generator, to the anode of the zener diode 14 and to the anode of the zener diode 11,

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the cathode of which is connected to the cathode of the silicon driver with the output 33 of the pulse generator and to the cathode of the Zener diode 27, the anode of which is connected via a resistor 24 to the input 31 of the pulse generator, the output 35 of the pulse generator through a resistor 25 is connected to the base of the transistor 15, a zener diode 28, the cathode of which is connected to the cathode of the diode 21, the anode of which through a resistor 26 is connected to one output of the coil 1 of a magnetic starter.

The device works as follows.

The power supply voltage is applied to the device at points 5 and 6. When the Start button is pressed, the magnetic starter is turned on and contact 4 is closed, shunting the Start 3 button. The capacitor 10 is charged along the circuit: point 5 - contact 4 - capacitor 10 - diode 19 - dinistor 9 - diode 8 - resistor 7 - point 6. Condenser 13 is charged along the circuit: point 5 - diode 19 - resistor 23 - capacitor 13 - . diode 19 - dynistor 9 - diode 8 - resistor 7 - point 6, capacitor 17 is charged along the circuit: point 5 - contact 4 - capacitor 17 - diode 18 - resistor 22 and distor 9 - diode 8 -. resistor 7 is point 6. The capacitors 10, 13, and 17 are charged to a voltage limited by zener diodes 11, 14, and 27, respectively. Pulses started from generator 30 periodically open transistor 15, through which charged capacitor 10 is connected to control electrode of triac 29, while triac is kept open until generator 30 is disrupted. In such a state, the device remains until the NB: the magnetic starter is switched off using the 2 Stop button or until the voltage of the power source is removed.

When you press button 2 Stop, the capacitor 17 is discharged during one half-period of the supply voltage through the circuit: point 6 - coil 1 magnetic starter - resistor 26 - diode 21 - zener diode 28 - capacitor 17 - triac 29 - point 5. Magnetic starter turns off , opens; pin 4, capacitor discharge 1 / leads to

the oscillation oscillation generator 30 rotates, which causes the triac 29. to be locked. After releasing button 2, the magnetic starter will not turn on.

When the supply voltage disappears or decreases below the switching voltage of the dynistor 9, the magnetic starter 1 is turned off, contact 4 is opened, capacitors 13 and 17 are discharged to resistors

12 and 16. The discharge of capacitors 13 and 1 to a certain voltage level leads to the cessation of oscillations of the generator of 30 pulses. The discharge time of the capacitor 13, leading to the cessation of oscillations of the generator 30, is 13-15 ms, and the capacitor 17 - corresponds to the permissible power interruption time - 3-10 s. If the voltage of the power supply is restored before the permissible power interruption time has expired, then the dynistor

9 opens and along the circuit: point 5 - diode 20 - resistor 23 - capacitor

13 - diode 19 - dynistor 9 - diode 8 - resistor 7 - point 6 a capacitor 13 is charged and a generator of 30 pulses is started, which leads to unlocking the triac 29, which turns on the magnetic starter 1.

If the power supply voltage recovers after the permissible power interruption time has elapsed, the magnetic starter switch does not occur, since the capacitor 17 is discharged through the resistor 16 and the generator 30 is closed at input 31, transistor 15 is locked and the triac 29 is not turned on. The device returns to its original state.

Diodes 18 and 19 are designed to disconnect the discharge circuits of capacitors 13 and 17. Zener diode 28 serves to prevent the capacitor 17 from discharging through button 2 Stop, resistor 26, diode 21. The voltage stabilizing Zener diode 28 is chosen greater than the voltage stabilizing Zener diode 27..

Claims (1)

Invention Formula A device for starting an asynchronous electric motor, containing a magnetic starter, the contacts of which are designed to connect the stator winding to the power source, one output of the magnetic starter coil through serially connected 564 the Stop button and the Start button shunted by the closing contact of the magnetic starter are provided with a first clamp for connecting to one output of the power source, the other terminal of the coil of the magnetic starter is equipped with a second clamp for connecting to the other output of the power source and to the series-connected first resistor, first diode and distor, the first capacitor is shunted by the first Zener diode, the terminals of the second resistor are connected in parallel to the second capacitor and the second Zener diode, the transistor, the third resistor, the third A capacitor, a second, third and fourth diode, characterized in that, in order to increase reliability of operation, a fifth diode, a fourth, fifth, sixth, seventh and eighth resistors, a third and fourth zener diodes, a triac and a pulse generator with two inputs, with positive and common leads, the leads of the third resistor are connected in parallel to the third capacitor and the third Zener diode whose anode is connected to the anode of the second diode, the cathode of which through the fourth resistor is connected to the anode of the dynistor and to the cathode of the third Anode whose anode is connected to the anode of a second zener diode, the cathode of which is connected to the first input of the pulse generator and connected via a fifth resistor to the cathode of the fourth diode, the anode of which is connected to the first terminal for connecting to the power supply, a triac controlling the electrode is connected in parallel to the Start button which is connected to the emitter of the transistor, the collector of which is connected to the common output of the pulse generator, to the anode of the second zener diode and to the anode of the first zener diode, the cathode of which is connected to the cathode with Mystora, with a positive output of the pulse generator and the cathode of the third Zener diode, the anode of which through the sixth resistor is connected to the second input of the pulse generator, the output of which through the seventh resistor is connected to the base of the transistor, the third anode of the stub, 1Ltron is connected to the fourth anode of the fourth stabilizer, cathode which is connected to the cathode of the fifth diode, the anode of which contains the eighth resistor of the co-circuit with one output of the coil of the simple start of the gel.