SU1377996A1 - Arrangement for dynamic braking of induction motor - Google Patents

Abstract

The invention relates to electrical engineering and can be used in electric drives of general-purpose mechanisms. The aim of the invention is to expand the scope and increase the accuracy of the stop. A distinctive feature of the device is the control of the presence of rotation of an asynchronous motor by the presence of voltage between the zero point of the stator winding 1 of the engine and the artificial zero point formed by means of resistors 7, 8 and 9 connected in a star and connected to the stator windings of the engine through the coil 6 of the zero relay tension 3 il. i (L

Description

i..J

Do

H

P1

with

QD 9d

The invention relates to electrical engineering and can be used in electric drives of mechanical mechanisms, such as cranes, rolling mills, and the like.

The aim of the invention is to expand the scope and improve the accuracy of the stop.

Figo shows the scheme of the proposed device; on fig. 3 - control circuit of contactors; FIG. 3 shows the dependence of the voltage on the winding of the zero voltage relay as a function of the rotation frequency.

A device for dynamic braking of an asynchronous motor contains an asynchronous motor 1, the stator circuit of which includes contacts 2 of a linear contactor, a dynamic braking contact, contacts 3 and A of which are connected to a circuit of a DC source 5, a zero voltage relay with winding 6 connected one output to the zero point of the stator winding, another output of the winding 6 is connected to one terminals of the first, second and third resistors 7,8,9, the other terminals of the resistors 7,8,9 through the third, fourth and fifth circuits The contacting contacts 10, 11, 12 of the brake contactor are connected respectively to three phases of the stator winding of the electric motor,

In the contactors control circuit, the start button 13 and the stop button 14 are connected to the coil control circuit

15 line contactor, the time relay coil 16 is connected to the control circuit through the contact 17 of the linear contactor, the contacts 18 of which and the contact 19. the zero voltage relay is connected to the control circuit of the coil 20 of the brake contactor,

The device works as follows:

When the button 14 is pressed, the stop is turned off by the coil 15 of the line contactor, and its contact 18 is closed in the circuit of the coil 20 of the dynamic braking contactor 20. At the same time, the contact 17 in the circuit of the coil 16 of the time relay is opened, which breaks its contacts in the circuit of the coil 20 of the brake contactor with a delay in time. Holding time katuiki

The 16 time delay is determined by the activation time of the brake coil 20

of the contactor and coil 6 of the zero voltage relay, which is turned on after supplying the supreme voltage in the two-phase circuits of the stator winding the zero voltage is kept in the on state until the moment when the asynchronous motor is completely stopped and, thus, automatically adjusts the deactivation time of the dynamic braking mode, regardless of fluctuations of the load torque and moment of inertia of the drive. The zero voltage relay performs the zero speed relay function because it is held in the on state only when the rotor of the motor is present, regardless of the direction of rotation and its frequency, and there are no pauses of controlled voltage characteristic of the analogue and the prototype. In an experimental study of the proposed device, the voltage on the turnip coil 6 in the dynamic braking mode (SmFig.C) has a clearly expressed nonlinearity, which favorably affects the operation of the relay.

The application of the invention expands the field of application of the device to the drive, which does not have the tilting direction of rotation in the opposite direction and eliminates false disconnections of the braking mode during the pause between voltage pulses on the zero voltage relay coil.

Claims (1)

Invention Formula A device for dynamically braking an asynchronous motor containing a brake contactor with closing contacts, a DC source is intended to be connected via two closing contacts to two phases of the stator winding, a zero voltage relay, the winding of which with one output is intended to be connected to the zero point of the stator winding The other terminal of the winding of the zero voltage relay is designed to be connected to one terminal of the first resistor, characterized in that, in order to expand the field rimen 15 FIG. 2