RU2047263C1 - Control gear for three-phase induction motor - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: pushing START button 7 energizes coil of magnetic starter 2 over the following circuit: phase C, coil of magnetic starter 2, STOP button 6, START button 7, capacitor 8, phase B, which closes contacts 3,4,5. Current flows over circuit: phase C, coil of magnetic starter 2, STOP button 6, power contact 3, supply mains phase. Releasing START button 7 disconnects capacitor 8 from supply mains. In case of voltage failure in any of supply mains phases or fault in power contact 3 magnetic starter 2 will not operate. To switch off motor 1, STOP button 6 should be pushed. EFFECT: enlarged functional capabilities due to elimination of motor switching-on in case of phase failure or faulty contact in phase under check; improved reliability due to reduced quantity of power contacts. 1 dwg

Description

 The invention relates to electrical engineering and can be used in electric drives of general industrial mechanisms.

A device for controlling a three-phase asynchronous electric motor containing a magnetic starter and controls [1]
The disadvantage of this device is the limited frictional capabilities, since the device does not exclude the inclusion of an electric motor with an out-of-phase supply mode, as well as low reliability.

The closest in technical essence to the proposed one is a device for controlling a three-phase asynchronous electric motor, containing a magnetic starter with power contacts and a block contact, control elements in the form of "Start" and "Stop" buttons [2]
The disadvantage of this device is its limited functionality, since the device does not exclude the inclusion of an electric motor in case of a non-phase supply mode of the network and loss of contact of the magnetic starter, as well as low reliability.

 The aim of the invention is the expansion of functionality by eliminating the possibility of turning on the motor in an out-of-phase mode and loss of contact in a controlled phase while increasing reliability by reducing the number of power contacts.

 This goal is achieved in that in a device for controlling a three-phase asynchronous motor containing a magnetic starter with a coil and three power contacts designed to connect the phases of the stator winding to a power source, one terminal of the magnetic starter coil is connected to a terminal for connecting to the first phase of the power source, “Stop” and “Start” buttons, one of the terminals of which are connected to each other at a common point, a capacitor is introduced, one terminal of which is connected to the terminal for connection to the second phase of the source power supply, and the other terminal of the capacitor is connected to the other terminal of the Start button, the other terminal of the Stop button is connected to the other terminal of the magnetic starter coil, the common connection point of one of the terminals of the Stop and Start buttons is equipped with a tap designed to connect to the third phase of the stator winding of the electric motor.

 The drawing shows a circuit diagram of the proposed device for controlling a three-phase asynchronous motor.

 A device for controlling a three-phase asynchronous electric motor 1 comprises a magnetic starter 2 with a coil and power contacts 3, 4, 5 included in the retaining winding of the electric motor 1, the Stop button 6, made in the form of an opening contact group, the Stop button 7, made in in the form of an opening contact group, capacitor 8. Power contacts 3, 4 and 5 are designed to connect the phases of the stator winding to the network. One terminal of the coil of the magnetic starter 2 is equipped with a clamp for connection to the phase C of the supply network. The other terminal of the magnetic starter coil 2 is connected through the serially connected opening contacts of the Stop button 6, the closing contacts of the Start button 7 and the capacitor 8 are connected to the phase B of the supply network. The connection point of the buttons 6 and 7, respectively, "Stop" and "Start" is connected to phase A of the stator winding of the motor 1.

 The device operates as follows.

 When you press the "Start" button 7 along the circuit: phase C, the coil of the magnetic starter 2, the button "Stop" 6, the button "Start" 7, the capacitor 8, phase B receives power coil of the magnetic starter 2, the latter turns on, closing contacts 3, 4 and 5. As a result, the magnetic starter coil receives power in the circuit: phase C, magnetic starter coil 2, Stop button 6, power contact 3, phase A of the supply network. When the start button 7 is opened, the capacitor 8 is disconnected from the mains. In the absence of voltage in any phase of the supply network, as well as a malfunction of the power contact 3, the operation of the magnetic starter 2 will not occur.

 To turn off the electric motor 1, press the "Stop" button 6, the coil of the magnetic starter 2 loses power, contacts 3, 4 and 5 become in the initial position shown in the drawing, and the electric motor 1 is turned off.

 Wider functionality with a simultaneous increase in reliability is an advantage of the proposed technical solution compared to the prototype.

Claims (1)

 DEVICE FOR CONTROL OF A THREE-PHASE ASYNCHRONOUS ELECTRIC MOTOR, containing a magnetic starter with a coil and three power contacts designed to connect the phases of the stator winding to the power source, one terminal of the magnetic starter coil is connected to the terminal for connecting to the first phase of the power source, the Stop and P buttons ", one of the terminals of which are interconnected to a common point, characterized in that a capacitor is inserted into it, one terminal of which is connected to a terminal for connecting to the second phase of the power source, and another output to another output of the Start button, another output of the Stop button to another output of the magnetic starter coil, the common point of connection of one of the outputs of the Stop and Start buttons is equipped with a tap designed to connect to the third phase of the stator winding of the electric motor.