SU1471317A1 - Device for control of electric arc furnace electrode movement - Google Patents

Abstract

The invention relates to electrical engineering. The aim of the invention is to increase the service life of the electrode by reducing the mechanical load on it while putting it in charge. The electrode stop is fixed by the current overcurrent, measured by sensor 6, of its specified value, and the absence of electrode current, measured by current sensor 2. With the stop, key 8 is closed, the control action is fed to the input of the comparator unit 3, i.e. Additional feedback is introduced on the current exceeding the core of the specified value, which ensures the limitation of the force acting on the electrode with an emphasis, preventing it from breaking. 1 il.

Description

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The invention relates to an electro term and can be used in the electrical mode regulators of arc steelmaking furnaces with an electric TpoMexaHi-necKHM drive.

The purpose of the invention is to increase the service life of the electrode by neither the mechanical load on it with the emphasis in charge of

Figure 1 shows the block diagram of the device; figure 2 - characteristic of the nonlinear block

The device for controlling the movement of the electrode of an electric arc furnace contains voltage sensors 1 and 2 electrodes connected by outputs to the first and second inputs of comparator 3, the output of which is connected to a motor 5 for moving electrode through a thyristor converter 4 The core, the output of which, in turn, is connected to the input of the nonlinear block 7, the output of which is connected to the third input of the comparison unit .3 via the key 8, the control input of which is connected to the output of the logic element 9, to the input dam which is connected through the delay element 10, the first threshold element 11 and the second threshold element 12.

The device works as follows.

In the process of controlling the electric mode of an electric arc furnace, signals proportional to the voltage and current of the electrode from the outputs of the respective sensors 1 and 2. are fed to the first and second inputs of the comparison unit 3, where they are subtracted. When there is an imbalance signal at the output of block 3, a signal appears that equalizes the thyristor converter 4 and provides the movement of the electrode by means of the motor 5 in the direction of reducing the unbalance. When the furnace is in motion (or an arc break), the electrodes are at some distance from the charge, the arc current is zero and under pressure of the voltage signal, the motor 5 moves the electrode down. The electrode current is less than the threshold element 11, then: at the first input A logical element AND 9 with a time delay (due to element 10) appears a normalized signal. When the electrode touches a non-conducting mixture (non-metallic inclusions, sand, etc.), the arc does not light up, the electrode abuts against the charge, the load on the motor shaft 5 increases, and the core current measured by sensor 6 increases.

When the current exceeds the core ij, its given value i ,; the output of the nonlinear block 7 appears, the control action Ui.k (i (i ((. 3ciA where K is the proportionality coefficient. With the control action Ua at the input of the second threshold element 12 at the second input of the logic element I. 9 also is the normalized signal, the AND 9 logic element is triggered, and the key 8 closes the signal from its output. In this case, the control action of the UL is fed to the third input of the block, 3 comparisons, i.e. additional negative feedback on overcurrent is introduced its given value. T The feedback ensures the stabilization of the moment developed by the electric motor 5, and hence the limitation of the force acting on the electrode at an effort that prevents its breakdown. At the beginning of the downward movement of the electrodes in the dynamic acceleration mode, the current core briefly exceeds its specified value. the operation of the logic element And 9 introduced the element 10 of the delay on the appearance of the signal at the first input of the element 9. During the delay, which is tenths of a second, the electrode does not have time to reach contact with the charge, and when you stop the action of the delay is over, and the device is triggered inertia-free. When the arc is ignited, the signal from the output of the threshold element 11 disappears, and hence from the first input of the AND 9 element. At the same time, the key 8 opens, turns off the nonlinear block 7 from the third input of the comparison terminal 3, and the device works by adjusting the electric furnace mode. The set value of the current cor i, is selected 1.1-1.3 times more than the value of the statistical current of the motor when the electrode is released.

The proposed device for controlling the movement of the electrode of an electric arc furnace allows an increase in the service life of the electrode, which leads to an increase in the reliability of operation of the electric furnace.

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Claims (1)

Invention Formula A device for controlling the movement of an electrode of an electric arc furnace that provides current and voltage sensors in each furnace phase, the outputs of which are connected to the first and second inputs of the comparator unit, the output of which is connected to the input of a thyristor converter connected to the electrode output motor equipped with a current sensor the core, the control key and the logical element I, the first input of which is connected to the output of the first threshold element via the delay element, the second input I-ass. with the output of the second threshold element, and the output of the logic element AND is connected to the control of the input key, characterized in that, in order to increase the service life of the electrode by reducing the mechanical load on it while focusing on the charge, it is additionally equipped with a nonlinear unit, the input of which is connected to the output of the current sensor cor, the output with the inputs of the second threshold element and the key, the output of which is connected to the input of the third block, compare the input of the first threshold element to the output of the current sensor. Shig.