SU1339848A1 - Method of starting a group of electric motors from sunchronous generator - Google Patents

Abstract

The invention relates to electrical engineering and can be used in autonomous power supply systems, for example, ships, aircraft, and the like. The purpose of the invention is to reduce the start time of a group of electric motors. To achieve this goal, the synchronous generator is overexcited and the alternate start of the electric motors, and the start of the subsequent electric motor begins when the generator voltage reaches 0.95 of the nominal value while maintaining the overexcitation. A device for implementing the method comprises a driving motor 5 with a rotational speed sensor 6, an excitation controller 7, an 8-frequency relay relay1, power switches 10-13, a time relay with windings 22, 23. 2 Il. with (L with with with 00 00

Description

The invention relates to electrical engineering and can be used in autonomous power supply systems, for example, aircraft ships, etc.

The purpose of the invention is to reduce the start time.

FIG. 1 is an electrical schematic diagram of an apparatus for implementing the method as applied to three electric motors; in fig. 2 shows voltage and current patterns of the motors and the generator.

A device for starting a group of electric motors 1-3 from a synchronous generator 4 comprises a driving motor 5 with a rotational speed sensor 6, an excitation controller 7, a rotational frequency relay 8 with a closing contact 9, a first circuit breaker 10, a second, third and fourth circuit breakers with windings 11-13. power contacts 14-16, opening block contacts 17-19 and closing block contacts 20 and 21, first and second time relays with windings 22 and 23, and contacts 24 and 25 closing with time delay, voltage relay with winding 26 and closing The contact 27, the winding pins of the synchronous generator core are connected via the first power switch 10 and the power contacts 14-16 of the second, third and fourth switches to the pins of the stator windings of electric motors 1-3, the control input of the excitation regulator 7 is connected to the winding of the synchronous generator core ora 4, output - to the excitation winding, and the starting circuit of the excitation regulator 7 includes a closing contact 9 of the rotation frequency relay 8, a winding 26 of the voltage relay connected to power supply, one terminal of the closing contact 27 of the voltage relay closing the block contacts 20 and 21 of the second and third circuit breakers are combined and designed to connect one power supply wire, another output of the closing contact 27 of the voltage relay through the serially connected contacts of the first and second relays time and time delay 24 In this case, the disconnecting block contact 19 of the fourth power switch is connected to one terminal of the winding 13 of the fourth power switch, the other terminal of which is connected to the other terminals of windings 11 and 12 of the second and third power switches and windings 22 and 23 of the first and second time relay, and is intended to connecting another mains lead, one terminal of the winding 11 of the second power switch through its opening blocking pin 17 is connected to the other of the normally open contact 27 of the voltage relay the time of the contacts 24 and 25 of the time relay through the disconnecting block contact 18 of the third power switch is connected

to one output of the winding 12 of this switch, one output of the windings 22 and 23 of the first and second time relays, respectively, through the closing block contacts 20 and 21 of the second and third power switches are connected to one output of the closing contact 27 of the voltage relay.

FIG. 2 shows a diagram 28 of the voltage on the winding of the synchronous generator core 4; field current diagram 29

0 generator; diagrams 30-32 currents of engines 1-3; diagram 33 of the current generator core.

The device works as follows.

5 On the excitation winding of the generator 4, connected to the system by the switch 10, at a frequency of rotation close to the nominal, at the time moment to through the relay 8 of the rotation frequency, the initial excitation is fed to the excitation regulator 6

0 generator 1. When the generator voltage reaches 90-100% of the rated voltage, the voltage relay operates with winding 26 and closes the contact in the control circuit of the switches, turns on the second switch 11 of the first motor 1 at time t | The excitation current of the generator 4 at the same time reaches the value of the excitation current in the idling mode. The voltage on generator 4 decreases and the voltage relay with winding 26 opens contact 27 and regulator 7

The excitation Q forces the generator 4 to energize. After turning on the switch; 1 11 its block-contact 17 opens the power supply of the winding 11 of the switch and closes the power supply of the winding 22 of the first time relay, which with delay of time closes the contact 24 in the winding circuit 12 of the third switch of the second engine 2, which is turned on at time t2 (Fig. 2).

At the moment 2 of switching on the second engine, the level of excitation of the generator 4 reaches the level of force corresponding to the starting mode of the first engine 1. The starting process of the first engine 1 thermally not finished and during the time tj-t the generator 4 is loaded with starting currents of the first 5 and second 2 engines. The voltage relay is turned off, and the auxiliary switch 21 of the third switch turns on the second time switch, preparing to turn on the switch 13 of the third motor 3, which is connected at the moment of time

0 t4 and during the time tr, -14 generator 4 is loaded with starting currents of the second and third engines 2 and 3.

Diagrams of the change of the excitation current iii F (t) of the generator 4 and the voltage Ui f (i) of the winding of the generator core (Fig. 2)

5 are given for generators with excitation controllers in which the level of force depends on the load current of the generator, for example, with static amplitude-phase compounding systems; with brushless systems; with synchronous and asynchronous exciters, in which the excitation windings of the exciter are fed according to the compounding circuit according to the load current of the generator.

For generators with excitation regulators that use a source for excitation that does not depend on the generator load current, for example, with brushless systems with a exciter, the generator excitation current rises to the level of maximum force and maintains its value until the end of the last motor start. In this case, the motor starting transient process occurs at the maximum possible excitation current, which reduces the starting time of each engine and reduces the generator voltage deviations caused by the starting of the engines.

The proposed method of starting a group of electric motors makes it possible to reduce the total start-up time of all engines from cars.

five

0

nominal synchronous generator or several generators operating in parallel.

Claims (1)

The method of starting a group of electric motors from a synchronous generator, in which alternate connection of electric motors to the winding of the synchronous generator core with forcing its excitation is carried out, characterized in that, in order to shorten the start time, the first electric motor is connected to the winding of the synchronous generator core, forcing the excitation of a synchronous generator, determine the moment of the first achievement of the voltage on the winding of the synchronous generator core 90-100% of the nominal value and, the second electric motor is connected to the winding of the synchronous generator core without removing the excitation forcing and then all the electric motors are started in the same way. After the last electric motor is started, the excitation force of the synchronous generator is removed. d, tj, Its if .t7 i-i