SU1471243A1 - Device for protecting three-phase electric motor against abnormal mode - Google Patents

Abstract

The invention relates to the field of electrical engineering, in particular, to the protection of a three-phase electric motor from normal operation. The purpose of the invention is to simplify the design and increase the reliability of the device. The device contains buttons "Stop-start" 3, magnetic starter 4 with power contacts 5,6,7, closing 8 and disconnecting 9 block contacts, time relay 14, thyristor 18. If there is an open in the motor circuit or in the winding of the electric motor, then when pressing the "Start" button 3, the thyristor 18 does not open, the time relay 14 does not work, the intermediate relay remains on, which prevents the magnetic actuator 4 from activating, the signal lamp 17 is lit, indicating an open circuit. 1 il.

Description

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The invention relates to electrical engineering, in particular to devices for protecting electric motors.

The purpose of the invention is to simplify the design and increase the reliability of the device.

The drawing shows a circuit diagram of the device,

The device for protection of the electric motor 1 contains the Stop 2 and Start 3 buttons, the magnetic starter 4 with the power 1 winding closing contacts 5-7, locking 8 and softening 9 block contacts, the intermediate relay 10 with winding closing 11, 12 and disconnecting 13 contacts relay

14 time with a winding, having a delay when returning, closing 15 and disconnecting 16 contacts, signal lamp 17, thyristor 18, actuator contacts are connected to terminals 19-21

network, respectively. The first, second and third phases. To limit the current of the control electrode, a resistor 22 is turned on, a diode 23 is inserted to lock in the reverse voltage on the control electrode,

The winding of the mapping actuator 4 is connected to the first 19 and second 20 network terminals through the series-connected Stop 2 and Start 3 buttons, the closing contact 15 of the time relay 14 and the disconnecting contact 13 of the intermediate relay 10, the winding of which is bridged by the signal lamp 17 is connected to those same network terminals through series-connected buttons Stop 2, Start 3, opening the block-pin 9 of the magnetic actuator 4 and pushing the contact 16 time relay 14, the closing block-pin 8 of the magnetic actuator 4 shunts the series connected to opku Start 2 and make contact

15 relay-14 time, the first closing contact 11 of the intermediate relay 10 shunts the power closing contact 6 of the magnetic starter 4 The winding of the time relay 14 is connected to the first phase wire of the electric motor of the network after the power closing,

 contacts 5 of the map actuator 4 and to the circuit through the main circuit of the thyristor 18, the control electrode of which through the second end of pin 12 of the intermediate relay 10 is connected to the third ty phase wire

the electric motor behind the power closing contact 7 of the magnetic starter 4.

The device works as follows.

When you press button 3 Start, the magnetic starter 4 does not work as the contact 15 of the time relay 14 is open in its winding circuit, but the winding of the intermediate relay 10 and the signal lamp 17 along the circuit receive power: terminals 19 of the network - buttons 2 and 3 - pin 9 - relay coil 10 and lamp 17 - pin 16 - terminals 20 of the network. Relay 10 is activated, opens its contact 13 in the circuit of the winding of the magnetic actuator 4 and closes the contacts 11 and 12. When it is dead, the signal lamp

17 indicates that the motor 1 is not connected to the network. Through the contacts 12 of the intermediate relay 10 and the windings of the electric motor 1, the voltage is supplied to the thyristor 18, which opens into the positive half-period of the voltage and supplies power to the winding of the time relay 14 along the circuit: network terminal 20 - contact 11 - motor winding 1 - thyristor 18 relay coil 14 - neutral Time relay 14 should be chosen so that it dies off during the thyristor open state

18 (in the absence of such a relay, its winding can be bridged by a capacitor, which acts as a filter for a half-wave rectified line). The relay-14 time is triggered without delay, opens its contact 16 and opens contact 15. At the same time, the coil of intermediate relay 10 loses power and the warning lamp 17 goes out. Relay 10 turns off, opens contacts 11

and 12 and closes the contact 13. The winding of the magnetic actuator 4 is directed according to the target: terminals 19 of the network - knolls 2 and 3 - contact 15 - winding of the actuator 4 - contact 13 - terminals 20 of the network. At the same time, the thyristor 18 is closed and the relay coil loses power.

14, the contacts 15, 16 of which remain in the actuated state until the end of the delay time. Starter 4 is activated, closes its power contacts 5-7, connecting the motor 1 to the network, and the auxiliary contact 8,

Shuntyr Button 3 Start and Contact

15 time relay, opens the auxiliary contact 9, breaks the power supply circuit of the windings of the intermediate relay 10 and the signal lamp 17. After a set time delay, contact 15 opens and contact 16 of the time relay 16 closes, the reset of which does not affect the operation of the device .

If the power circuit 1 or the windings of the electric motor 1 is turned around, then pressing the button 3, the start of the thyristor 18 will not open, the relay 14 will not work, the intermediate relay 10 will remain on 1 to 1m, which prevents the magnetic actuator 4 to operate, and it will light up signal lamp 17 indicating an open circuit.

The thyristor 18 is selected in such a way as to exclude its spontaneous switching on from the phase voltage with an open circuit of its control electrode. In the absence of such a thyristor, an additional locking contact (not shown) of intermediate relay 10 can be included in its anode or cathode circuit.

Thus, the invention makes it possible to simplify the design of the device, and by eliminating one intermediate relay, and to increase the reliability of operation by providing a sequence of operation and switching off the switching devices.

Claims (1)

Invention Formula A device for protecting a three-phase electric motor from an abnormal mode, containing a magnetic starter, the power contacts of which are designed to be connected in series into each phase wire of an electric motor, signal lamp, Stop button, one output connected to a terminal for connecting to the first phase of the network, a Start button connected in series with With the Stop button, the winding of the magnetic starter, one output of which is connected through its own five 0 five 0 five 0 five 0 A contact block with one point of connection of the specified buttons, an intermediate relay with a pasNfbiKarcuciM contact, a time relay with a return delay with a short-circuit TI open-ayup. contacts, with the first terminals of the open time relay and an intermediate relay combined and connected to the terminal : -1e for connecting to the second phase of the network5 is necessary so that, in order to simplify the design and increase the reliability of operation, it is additionally equipped with a thyristor, and the intermediate relay is supplied with two make contacts, at Volume The closing time relay contact is connected between the point of connection of the Start button with the opening magnetic contact of the magnetic starter and the TO4Kofi connection of the closing magnetic contact of the magnetic starter with one terminal of its winding, the other terminal of which is connected to another output of the disconnecting contact of the intermediate relay, one terminal of which winding is connected to the point of connection of the disconnecting block contact of the magnetic actuator with the output of the signal lamp, and the other output of the winding npoMe; fcy t of the internal relay is connected to another output of the signal lamp and connected to a different terminal of the disconnecting time relay, the first wiring & an intermediate relay contact connects the magnetic contact of the magnetic starter connected to the terminals for connection to the second phase of the network and the electric motor, while the anolyristor is connected to for connecting the first phase electric motor the cathode is connected to one terminal of the winding of the time relay, the other terminal of which is connected to the terminal for connection to the neutral wire of the supply mains, and the control electrode of the thyristor through the second circuit An intermediate relay contact is connected to a terminal for connection to the third phase wire of the motor.