SU1539944A1 - Device for control of three-phase induction electric motor - Google Patents

Abstract

The invention relates to electrical engineering and can be used in electric drives of machine tools. The purpose of the invention is to increase reliability. In the device for controlling a three-phase asynchronous electric motor, during the start-up, the two phases of the stator are connected to the mains by the contacts 3, 4 of the main contactor, which are opened during braking. In this case, the stator phases are powered through braking and shunting (III) thyristors 11, 12, which are locked at the end of braking, while they are controlled as a function of the motor speed 1. When starting, the third phase of the stator and the phase connected to the thyristor 11, They are connected to the mains by the contacts 24, 25 of the additional contactor, which open at the end of braking after locking the thyristor 11, while controlling the additional contactor as a function of the current (voltage) of braking the motor 1. Tiris control circuit 11 collected before Hur, and a thyristor control circuit 12, - after turning off the main contactor. 1 il.

Description

and pin 5 in the control circuit of the shunt-.r is safe to maintain, and

20

thirty

power thyristor 12 closes and opens power contacts 3 and 4, while in the process of their opening the brake thyristor 11 with its pre-assembled control circuit of contact 16 of the relay with coil 15 opens and shunts contact 3 in the conducting half-cycle, which significantly reduces the time and intensity sparking, and hence the degree of its burning. At the same time, contacts 24 and 25 remain closed, since coil 22 remains switched on by contact 23 of the relay with coil 19. After opening of contacts 3 and 4, relays with coil 15 also remain turned on due to the EMF signal of rotation of the motor 1 and its closing contact 16 It leaves the brake control circuit switched on and, additionally, through contact 5, the shunt thyristors 11 and 12. At the same time, a braking current flows through the stator winding 11 through the thyristor 11, due to which the relay with the coil 19 is kept in the on state. A thyristor 12 is opened to the nonconducting half-period for the thyristor 11 of the supply voltage, through which current flows due to the electromagnetic energy stored in the stator windings.

also the lifetime of the device.

Claims (1)

Invention Formula A device for controlling a three-phase asynchronous electric motor, containing a main contactor with a coil, with two power closing, opening and closing contacts 25 one terminals of the main contact contacts of the main contactor are designed to connect an electric motor to the two phases of the stator winding, a Stop button, one output of which is connected to the first terminal for connection to a power source, another to the Stop button is connected to one output of the Start button and one output of the closing contact main contactor, braking unit, you 35 filled in the form of brake and shunt thyristors with control circuits, for the output of the braking unit are formed by the braking thyristor leads and connected respectively to the leads of the first power make contact of the main contactor, the other lead of the second power make contact of the main contactor is provided with a clip for connecting to one the network phase, the third output of the braking unit is formed by the cathode output of the shunt thyristor and prednaz 45 When the engine 1 is stopped, the extracted signal of the EMF of rotation becomes zero, the relay with coil 15 filled in the form of brake and shunt thyristors with control circuits, for output of the braking unit, are formed by the leads of the brake thyristor and are connected respectively to the terminals of the first power closing contact of the main contactor, another terminal of the second power closing contact of the main contactor is provided with a clip for connection to one phase of the network, the third output of the braking unit is formed by the cathode output of the shuntyr thyristor and is designed to connect to the third phase The 16,503e stat ° ° Pn ° ° motor electric motor closes and opens its contact with a thyristor 11 and a voltage divider, two leads and 12, after which the windings are de-energized for connecting the stator and, therefore, the relay with no the first and third phases of the stator coil 19, which is turned off and. winding, and its third output is connected to the first output of the rotational speed sensor, the second output of which is connected to the main relay coil with a closing contact in the brake and shunt control circuits opens its contact 23, which causes the power to turn off of the coil 22 of the additional contactor and the opening of its contacts 24 and 25. As the opening of contacts 24 and 25 is happening, 55 also the lifetime of the device. Invention Formula 20 thirty four A device for controlling a three-phase asynchronous electric motor, containing a main contactor with a coil, two power closing, opening and closing contacts 25 one terminals of the main contacting power contacts are designed to connect to the two phases of the stator winding of an electric motor, the Stop button, one terminal of which is connected to the first terminal for connection to a power source, another terminal of the Stop button is connected to one terminal of the Start button the contactor, the braking unit, filled in the form of braking and shunt thyristors with control circuits, for outputting the braking unit are formed by the braking thyristor terminals and connecting us respectively to the terminals of the first main circuit switching contact of the contactor, the other terminal of the second main circuit switching contact of the contactor is provided with a clamp for connection to one phase of the network, the third terminal block is formed by inhibiting the cathode terminal of the thyristor and shunt prednaz45 50 . 55 the thyristors of the braking unit, one output of the coil of the main contactor is provided with a second terminal for connecting to the power supply, characterized in that, in order to increase reliability, an additional contactor with two closing contacts, an additional relay with a coil, with opening and closing contacts, a capacitor, a resistor and a diode, the main contactor is sn.bzhen with a second closing contact, the anode of the diode is connected to the third output of the braking unit, the cathode of the diode is connected via a resistor to one output of the coil A capacitor bridged relay, another coil output of the auxiliary relay is designed to connect the stator winding to the first phase. Another coil lead of the main contactor is connected to another output of the closing contact of the main contactor and to another output of the Start button, one coil output of the additional coil the contactor is connected to wto 0 five five 0 A clip for connecting to a power source, another coil terminal of an additional contactor is connected to one pins of the make contact of an additional relay and a second make contact of the main contactor, the other pins of which are combined and connected to one output of the Stop button, one pins of the make contacts of the additional contactor are provided with terminals for connection to the other two phases of the network, another output of the first closing contact of the auxiliary contactor is connected to another output of the first power supply the main contactor's closing contact, another output of the second contact of the additional contactor is designed to connect to the third phase of the stator winding, the main contact of the main contactor is included in the control circuit of the decelerating thyristor of the braking unit, the third output of the rotational speed sensor is connected to the second phase of the electric motor stator tel.