SU1341696A1 - Device for protecting three-phase electric motor against induction mode of operation - Google Patents

Abstract

The invention relates to electrical engineering. The chain of the invention consists in reducing the weight and size parameters and increasing the reliability of operation. When the voltage level in one of the phases decreases and this phase passes into the generator mode (for example, phase A), the voltage relay 1 opens the contact 7 in the intermediate relay 4 circuit. The intermediate relay coil is de-energized, its switching time is switched to phase shifting unit 10, which will provide an artificial interruption of phase A, the opening contacts .14 and 15 will close and the phase-shifting unit will be activated, ensuring the full utilization of the power of the electrolyte. . O) CO O5 with O5

Description

The actual phase failure A, opening contacts 14 and 15 is closed and the phase-shifting unit is activated, ensuring the full use of the power of the protected motor.

If the voltage level decreases in phase C, then the voltage relay 3 opens its contact in the intermediate circuit. The invention relates to electrical engineering and can be used for relay protection of three-phase electric motors.

The purpose of the invention is to reduce the metal content of indicators and increase the reliability of operation.

The drawing shows a schematic diagram of a device for protecting a three-JQ relay 6. Its switching motor from asymmetry 13 switches to phase shifting unit 10, providing an artificial interruption of phase C, and contacts 18 and 19 are opened and injected phase-shifting unit 10, ensuring the full use of the power of the protected motor.

When light one of the phases in

rich modes.

The device for protection of a three-phase electric motor from asymmetric modes includes three voltage relays 1-3, connected to phase mains voltages, three intermediate relays 4-6, .. switched on via voltage contacts 7-9 of the phase voltage relay, phase shifting unit 10, connected via switching contacts 11-13 and disconnecting contacts 14-19 of intermediate relays to motor phases A1, B1 and C1.,

Device for protection of three-phase asynchronous motor from asymmetric modes works as follows.

If there is no voltage at the input of the device to protect the three-phase electric motor from asymmetric modes, there is no voltage on the windings of voltage relay 1-3, voltage relay 1-3, intermediate relays 4-6, phase shifting unit 10 do not work. The state of the diagram corresponds to the drawing.

When a symmetrical voltage is applied to the input of a device for protection of a three-phase electric motor from asymmetric modes, relays 1–3 are activated, which close their closing contacts 7–9 in the power supply circuit of intermediate relays 4–6. Intermediate relays 4-6 are triggered, their framing contacts 14-19 are opened, and the switching contacts 11-13 are switched, the engine is turned on and is working normally. The phase shifting unit does not work.

When the voltage level drops in one of the phases and this phase enters the generating mode (for example, phase A), the voltage relay 1 opens its contact 7 in the intermediate relay circuit 4. The intermediate relay 4 coil de-energizes, its switching contact switches to phase shifting unit 10 that provides art35

The period of operation of the device for protection of a three-phase electric motor from asymmetric modes works in the same way as when the voltage level in one of the phases is lower than the allowable one. When starting the engine with dangling

The 25 phase of the network (for example, phase B) of the voltage relay 2 does not operate, its contact 8 in the intermediate relay 5 circuit does not close, the relay 5 does not operate, its switching contact 12 remains

30 is closed to the phase shifter 10, and the opening contacts 16 and 17 remain in a closed state, which corresponds to the input of the phase shifter 10, thereby starting the motor easier and ensuring full use of its power in the steady state.

When two phases break (for example, A and B), phase C is applied to the motor,

Q which is similar to disconnecting the engine from the network.

With the elimination of asymmetry of the supplied voltage or of the disconnection of the mains phase, the device for protecting the motor 45 from asymmetrical diagrams returns to the initial state.

A device for protecting a three-phase electric motor from an asymmetrical mode makes it possible to reduce the number of cells and increase the reliability of the device.

Claims (1)

Invention Formula gg A device for protection of a three-phase electric motor from an asymmetric mode, containing three voltage rails, the coils of which are provided with leads for switching on the power supply and zero phase A phase, the disconnecting contacts 14 and 15 are closed and the phase-shifting unit is activated, ensuring full use of the protected power electric motor. If the voltage level decreases in phase C, then the voltage relay 3 opens its contact in the intermediate relay circuit 6. Its switching contact 13 intersects phase shifting unit 10, providing an artificial open circuit phase C, and contacts 18 and 19 open and enter in action phase-shifting unit 10, ensuring the full use of the power of the protected motor. When light one of the phases in 35 The period of operation of the device for protection of a three-phase electric motor from asymmetric modes works in the same way as when the voltage level in one of the phases is lower than the allowable one. When starting the engine with dangling The 25 phase of the network (for example, phase B) of the voltage relay 2 does not operate, its contact 8 in the intermediate relay 5 circuit does not close, the relay 5 does not operate its switching contact 12 remains 30 is closed to the phase shifter 10, and the opening contacts 16 and 17 remain in a closed state, which advances the input of the phase shifter 10, thereby starting the motor easier and ensuring full use of its power in the steady state. When two phases break (for example, A and B), phase C is applied to the motor, Q which is similar to disconnecting the engine from the network. With the elimination of asymmetry of the supplied voltage or of the disconnection of the mains phase, the device for protecting the motor 45 from asymmetrical diagrams returns to the initial state. A device for protecting a three-phase electric motor from an asymmetrical mode makes it possible to reduce the number of cells and increase the reliability of the device. Invention Formula gg A device for protection of a three-phase electric motor from an asymmetric mode, containing three rails of voltage, the coils of which are provided with leads for switching on a bridged and neutral wire of the network, three intermediate relays, the coils of which are provided with leads for connecting to the phase and zero wires of the network through voltage relay closing contacts, intermediate relay contacts for connecting the motor terminals to the mains phases, phase shifting unit in the form of successively connected chokes and a capacitor, - in order to reduce weight and overall dimensions and increase the reliability of operation, the intermediate relay contacts are implemented in the form of switching contacts, the disconnecting group of which one contact in each phase is connected to the common point of the capacitor and the throttles, which connected to the combined first outputs of the newly inserted intermediate relay intermediate contacts, the second opener contacts of the intermediate relays in each phase are connected respectively: the first phase relay to the third one, the second phase relay to the first one, and the third phase relay to the second output of the electric motor The capacitor switch is connected to the combined first switches of the additionally inserted contact opening intermediate relays, the second opening switches of the intermediate contacts of each relay with dineny, respectively: the first phase switch - to a second relay of the second phase - the third, the third phase switch - a first vshodami motor.