SU1647746A1 - Device for protecting three-phase motor from two-phase operation - Google Patents

Abstract

The invention relates to electrical engineering, in particular to relay protection of three-phase electric motors. The purpose of the invention is to increase the reliability of the protection device. When the voltage on one of the phase terminals of the electric motor 1, for example, the first, disappears, the current relay 4 de-energizes and closes its contacts 13 and 15. A circuit is created between the second and third phase wires through the contacts of the current relay 13, diode 8, and the coil 2 of the electromagnetic release switch , pin 15, diode 9. The switch turns off, breaks its power circuits, you 3. the electric motor stops. 1 il.

Description

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The invention relates to electrical engineering and is intended to protect three-phase alternating current electric motors when the voltage disappears in one of the phases of the network.

The aim of the invention is to improve the reliability of the device.

The drawing shows a diagram of the device.

The device for protection of a three-phase electric motor 1 from operating on two phases contains a switch with an electromagnetic release 2, the power contacts 3 of which are included in the phase wires feeding the electric motor 1, the first 4, the second 5 and the third b current relay, the coils of which are included in the first, second and the third phase wires feeding the electric motor, the first 7, second 8, third 9 and fourth 10 diodes. In this case, the anode of the first diode 7 is connected to a terminal for connecting the electric motor to the first phase output, and the cathode is connected to a common point of the first terminals of the second 5 and third batch relays connected in parallel to the first disconnecting contacts 11 and 12, the anode of the second diode 8 is connected to the terminal for connecting to the second phase output of the electric motor, and the cathode with the first output of the first disconnecting contact 13 of the first current relay A, with the second conclusions of the first disconnecting contacts 13, 11 and 12, the first 4, the second 5 and the third B current relays Inen and connected to the first output of the electromagnetic trip unit 2 switch, the cathode of the third diode 9 is connected to the anode of the second diode 8, the anode of the third diode 9 - with the first output of the second disconnecting contact 14 of the third current relay 6, the cathode of the fourth diode 10 - with a terminal for connection to the third the phase output of the electric motor, and the anode with the first terminals of the second parallel-connected disconnecting contacts 15 and 16 of the first 4 and second 6 current relays, while the second terminals of the second disconnecting contacts 15,16, 14 of the first 4, second 5 and third 6 t postglacial combined relay and connected to the second terminal of the electromagnetic releaser 2 switch.

The device works as follows.

If there is voltage on all the phase conductors and the switch is turned on, its power contacts 3 are closed. A motor current flows through the coils of 4-6 current relays, and all the opening contacts of 11-16 current relays open.

If the voltage disappears on one of the phase conductors, for example, the first, the current relay 4 de-energizes and closes its contacts 13 and 15 The current from the second phase wire through diode 8 and the first contact 13 of the first current relay 4 through the coil of the electromagnetic release 3, the second contact 15 the same current relay 4 diode 9 flows to the third phase wire. The switch turns off and opens the power contacts 3, stopping the electric engine 1.

In the same way, tripping occurs when the voltage is lost at any other phase level.

Diodes 7-10 serve to protect circuits.

Claims (1)

5 control from k.z. when the switch is turned on, when the contacts 11-16 are closed. The invention The device for protection of a three-phase electric motor against operation on two phases 0 containing a switch with an electromagnetic release, the power contacts of which are intended to be connected to the phase conductors supplying the electric motor, the first, second and third current relays, The 5 coil terminals of which are intended to be connected to the first, second and third phase wires feeding the electric motor, current relay contacts, characterized in that, in order to increase the reliability of the device, it is additionally equipped with four diodes, while the anode of the first diode is connected to the terminal to connect to the first phase output of the motor, and the cathode is connected to a common point 5 first terminals of the first and second disconnecting contacts of the second and third current relays connected in parallel, the anode of the second diode connected to the terminal for connecting the second phase output of the electric motor, and the cathode 0 to the first output of the first disconnecting contact of the first current relay, the second and third relays are combined and connected by the first q terminal 5 coil of the electromagnetic trip switch, the cathode of the third diode is connected to the anode of the second diode, the anode of the third diode is connected to the first output of the second normally open contact of the third current relay, the cathode of the fourth diode is connected to the terminal for connection to the third phase output of the electric motor, and the anode to the first terminals second parallel disconnecting 5 contacts of the first and second current relays, while the second pins of the second disconnecting contacts of the first, second and third current relays are combined and connected to the second output of the coil of the electromagnetic release switch.