SU826575A1 - Electric arc furnace power regulator - Google Patents

Description

(54) ARC POWER REGULATOR

one

The invention relates to electrothermal, in particular, steelmaking in arc furnaces of particle board, and can be used in electrometallurgy to regulate the power of particleboard by displacing an electrode.

A three-phase chipboard power controller is known, which contains a software control unit, one output of which is connected to the voltage switch of the furnace transformer and the other to the motor controller for moving the electrodes of each phase 1.

When the furnace is turned on, the displacement controller of the electrodes maintains a preset control parameter corresponding to the value of the power input to the furnace. In the process of melting wells in bore containing both conductive materials (ore, metal scrap) and non-conductive sclac-forming components (limestone, fluorite, etc.), a decrease in the charge conductivity in areas with a high content of non-conductive materials leads to power reduction of the electric arc. In this case, the automatic controller

will move the electrode down in the direction of the stitch. In this case, the electric arc is not fully restored, and the pressure of the electrode on the welder increases, creating a pre-emergency situation.

A device for controlling the movement of chipboard electrodes is known, which contains a mechanical force sensor for measuring loads applied to the electrode device of the furnace and is equipped with a motor and a mechanism with a cable-drum transmission for moving the electrode. The device contains a system for automatic regulation of the electrical mode of a particle board and a compensation unit for slowly varying forces, which is used to take into account potentially non-hazardous forces caused by the consumption of the electrode and the change in the load on the electrode assembly from the current supply when the electrode position changes. When the pressure of the electrode on the charge (penetration of non-conductive components),

The control system stops moving the electrode until the dangerous force is eliminated, by melting or burning non-conducting components of charge 2.

The drawbacks of the device are significant errors in determining the place of occurrence of dangerous forces and the large inertia of mining due to the presence of elastic links and play in the system of a cable-drum mechanism and a special mechanical force sensor associated with it (cable tension). The residual tension of the cable (after switching off the electrode displacement motor) does not correspond to the initial one that caused the motor shutdown, which leads to instability of the welding mode of the nonconducting charge components. The error in determining the place of occurrence of dangerous forces and the inertia of mining leads to electrode breakdowns, and the instability of the mode leads to an increase in the time of melting. The system is difficult to operate due to the presence in the control system of the signal generator, which compensates for non-hazardous forces (weight, electrode position) requires periodic reconfiguration of the comparators due to the imbalance of the electrode counterweight system. The system is complex in design, as well as during commissioning and operation, and cannot be used for modern furnaces equipped with a rack drive gear.

A power regulator for an electric arc furnace is known. It contains voltage and current sensors for each electrode connected by outputs to two inputs of a comparator unit connected by a third input to an output of the mode controllers, and the output to one of the switch inputs, the second input of which is connected to a standardized setting device the bipolar signal, the output — with the first input of the node forming the gain, the dead zone and the output signal levels when the electrode is moved, the output of which is connected to the input of the thyristor converter connected to the engine output electrode movement, provided with the armature current sensor and engine speed sensor connected to the output to the second input node forming -3.

A disadvantage of the known device is that when switching to melting technology, which involves loading non-conductive slag-forming components in the form of a dense compact layer under a thin upper layer of conductive materials, the system will tend to work out the increasing mismatch between the arc current and phase voltage by forcing the electrode to move down in the direction of the charge that breaks out the electrode breakage.

The purpose of the invention is to increase the productivity of the furnace by intensifying the process of melting non-conductive layers, automating the process and reducing the specific energy consumption.

The goal is achieved by the fact that the linking of the formation unit to the thyristor converter M. is made via a controlled key connected to a control input via a time delay block

with the output of the logic element 3 And, the first input of which through the chain of the delay element and the threshold current element of the motor core is connected to the current sensor core, the second through the logical element NOT to the output of the threshold element of the electrode working current, and the third to the output of the minimum threshold element the electrode current, the input of which, through the first input of the threshold element of the working current of the electrode, is connected to the output of the electrode current sensor, and the second input of the threshold element of the working current of the electrode is connected to the output mode adjuster.

The drawing shows the regulator block diagram.

The device contains sensors 1 and 2 of voltage and current of the electrode, designed to form signals proportional to the phase voltage and current of the electrode, the output of which is connected to the input of comparator 3, where the control parameter signal is compared with the voltage of the reference coming from the task 4 . The output of the comparison unit 3 is connected to the formation unit 5, which forms the required gain factor, deadband, output

levels of the regulator signal when raising and lowering the electrode, and also provides manual control when connecting the source of the normalized bipolar signal 6 through the switch 7.

The output of the functional unit 5 is connected by a thyristor converter 8 through a key 9, which is included in the logic block, marked with a dotted line.

Thyristor Converter 8 provides power to the engine 10 displacement

electrode, which, in turn, is connected to the sensors 11 and 12 of the rotational speed (rotational speed) and the current of the engine core. The rotational speed sensor 11 is connected to the node 5 to form a speed feedback to ensure stability.

speed characteristics and the necessary dynamic qualities of the drive.

The current sensor 2 is connected to the threshold elements 13 and 14 of the minimum current and operating current of the electrode. The second input element 14 is connected to the output of block 4 tasks.

Claims (3)

1. USSR author's certificate number 548942, cl. H 05 B 7/148, 1977 2. US patent number 3914526, cl. 15-13 1975. 3.Sydorenko MF, Kosyrev D, I. Automation and mechanization of electric arc-smelting and ferroalloy production, M., Metallurgists, 1975, p. 41