SU1677882A1 - Device for controlling electric arc installation - Google Patents

Abstract

The invention relates to electrical engineering. The aim of the invention is to increase plant capacity by improving the quality of control. The device provides automatic exposure of the arc period for a given power at the flow rate of the electrode and at changes in the level of the liquid metal with a high level of speed due to the analog circuit elements. The device is equipped with an additional power source, which allows to automatically initiate an electrical discharge into the interelectrode gap and preheat the furnace before turning on the main power source, whose power increases gradually. 2 Il.

Description

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WITH

The invention relates to electrothermal, in particular, devices for controlling the mode of a direct current arc furnace.

The purpose of the invention is to increase plant productivity by improving the quality of control.

Figure 1 shows the block diagram of the device; 2 shows timing charts of the control device.

The device for controlling the mode of the arc installation 1 with electrode 2 consists of switching units 3 and 4, power sources of auxiliary 5 and main 6, switching unit 7, electric motor 8, current sensors 9 and 10, voltage sensor 11, zero organ 12, three time relays 13, 14, 15, coincidence units 16, 17, current setting units 18 and voltage 19, adder 20, switch 21, current regulator 22, pulse driver 23, comparison unit 24, deadband driver 25.

The main elements of the temporal characteristics in FIG. 2 are

t / is the start-up of the furnace, the inclusion of an auxiliary power source, the beginning of the electrode movement downwards;

t2 is the contact of the electrode, the cessation of the movement of the electrode downward, the beginning of the upward movement;

t3 — turn on the main power source;

tq — turn off the auxiliary power source;

ts is the exit to a given operating mode of the furnace, stopping the movement of the electrode upwards;

about

vj 1 00 00

YU

te arc break;

t7 — turn off the main power source, start the movement of the electrode upwards;

te - stopping the movement of the electrode upwards.

The device works as follows.

In the initial state of installation 1, electrode 2 is in the upper non-operating position.

At start-up of installation 1, switching unit 3 and auxiliary power source 5 are turned on and the switching unit 7 is used to move the electrode downwards using an electric motor 8. At the moment of contact of the electrode 2 with the metal, a current of the auxiliary power source 5 is generated. organ 12 is supplied to the switching unit 7. Electrode 2 begins to move upwards, and time relay 13 switches on the main power source 6 through the switching unit 4. When the current of the main source 6 arises, the signal from the current sensor 10 and d voltage trickle 11 enters the coincidence unit 16 and, via time relay 14, turns off the auxiliary power source 5 via the switching unit 3. The signal from the current reference unit 18 and the current and voltage feedback signals are fed to the adder 20 and through the switch 21- to the current regulator 22 and the pulse shaper 23. The installation is controlled by the current of the main power source 6.

In order to maintain the arc voltage equal to the signal set from the voltage setting block 19 and the voltage sensor during operation of the installation, e comparison unit 24 is received. Depending on the dead zone selected, a signal is generated to control the motor 8 for moving the electrode 2.

When the arc is broken, the coincidence unit 17 generates a signal that closes the switch 21 via time relay 15. The main source 6 is turned off and the signal is output to the switching unit 7 to move the electrode 2 to the upper non-operating position.

The switching unit controls the motor for moving the electrode according to the following algorithm: if there is a signal at the output of switching unit 3 (the second input of the engine control unit), the motor moves the electrode down, if there is a signal at the output of the zero organ 12 (fourth input), the motor moves the electrode up and in the presence of a signal at the output of time relay 15 (first input), the direction of movement of the electrode is determined by the signal from the driver 25.

Thus, at time ti (see Fig. 2), the auxiliary power supply -11c is turned on and the voltage Ui is applied to the electric motor, which moves the electrode downwards. At time i, the electrode contacts the metal in the furnace, a current of AND of the auxiliary source and

Under the action of voltage U2, the electrode begins to move upwards. The arc is ignited and the countdown of the turn-on time of the main power supply begins - n. At time t2, the electrode contacts the metal in the furnace, current A of the auxiliary source arises and under the action of voltage U2 the electrode begins to move upwards. The arc is ignited and the countdown of the on-time of the main power supply — T begins. At the instant of time, the main power source turns on with a smooth rise of the current 2 and the voltage LU, and the off-time off-delay time G2 starts. At the moment of time, the auxiliary power supply is turned off. At the time ts, the specified operating mode of the furnace is established and the electrode moves upwards. If at any moment of time (after b) the arc breaks, the time relay unit will turn on, counting the time Гз - delay to turn off the main power supply (J4. After turning off the main power supply at time t, the motor moves the electrode to the upper idle position. At time ta, the movement is completed.

The use of the device allows

increase the speed of the control system. Introducing an automatically controlled auxiliary power supply improves reliability.

electrical equipment by eliminating the short circuit mode at the start-up of the furnace, reduce the heating time of the furnace and thereby increase its performance.

Claims (1)

Invention Formula A device for controlling the mode of an arc installation, comprising a main power source with a first current sensor connected in parallel A voltage sensor, a comparison unit, the first input of which is connected to the output of the voltage setting unit, the second input to the output of the voltage sensor, and the output to the input of the dead zone generator, the motor for moving the electrode and the adder, characterized in that increase plant capacity by improving the quality of control, it additionally contains an auxiliary power source connected in parallel with the main source with a second current sensor, two switching units, two units neither, three time relays, a zero-organ, a current setting unit, a key, a switching unit, a current regulator and a pulse shaper, whose input is connected to the key output through the current regulator and the output to the first control input of the main power source The second control input of which is connected to the output of the first switching unit, the output of the first current sensor is connected to the first inputs of the matching blocks and the adder, the second inputs of which are connected to the output of the voltage sensor, the third input of the adder is connected to the output 0 five 0 the current setting unit, and the output to the key input, the control input of which is connected to the output of the first time relay, also connected to the first input of the first switching unit and the first input of the switching unit, the input of the first time relay is connected to the output of the first coincidence unit, the output of the second block match via a second time relay is connected to the input of the second switching unit, the output of which is connected to the control input of the auxiliary power source and to the second input of the switching unit, the third input of which is connected to you the driver of the dead zone, and the output with the electrode displacement motor, the output of the second current sensor is connected to the zero-organ input, the output of which is connected to the input of the third time relay and the fourth input of the switching unit; the output of the third time relay is connected to the second input of the first switching unit . FIG. one Phases. 2