SU752824A1 - Three-phase electric furnace automatic power regulator - Google Patents

Description

(54) AUTOMATIC POWER REGULATOR OF THE ARC THREE-PHASE ELECTRIC PROCESSES The invention relates to electrothermia. An electric arc power regulator is known, which contains current and voltage sensors, a comparison unit, an amplifier, and an electrode movement drive Sh. An automatic electric arc power regulator is also known, containing for each phase arc current and phase voltage sensors connected respectively to discharge units current value and phase voltage connected to two inputs of the comparator unit, the output of which is connected via an amplifier to the executive mechanism for moving the electrode {2. The disadvantage of the known regulators is that they do not ensure the prevention of electrode breakdowns during collapses. The circuit of the invention is to increase the reliability of the furnace. For this purpose, the regulator is provided for each phase with a voltage detection unit on the arc, the output of which is connected to the first input of the newly entered match element connected by the second input to the unit through the selection unit of the effective voltage value on the arc. dividing the effective value of the arc current, and the output through the time relay to the additional inputs of the comparison units of all phases. The drawing shows a block diagram of an automatic power regulator to a 1SH electric furnace for a single phase. The automatic regulator of power of the electric arc furnace contains a current sensor 1, sensors 2, 3 and 4 of the first arc current with respect to time for the 1st, 2nd, 3rd phase, furnace voltage voltage sensor 5, block 6 arc, block 7, the selection of the effective value of the voltage on the arc, the element 8 coincidence, relay 9 time, block 10 the selection of the effective value of the phase voltage of the furnace, block 11, the power setting, block 12 allocation ae swivel value of the arc current, block 13 comparison, power amplifier 14, isp sh shank mechanism 15, Electrode 16. A signal proportional to the arc current, removed from datchshsa 1 and arc current through the power specifying unit 11 is supplied to the input of block 12 separating deystvuyuscheTG current values. The signal from the output of the active current arc extraction unit 12 is applied to the first input of the comparison unit 13. The signal proportional to the phase voltage of the furnace is removed; From the phase voltage sensor of the furnace, it is fed through a block 10 for extracting the current value of the phase voltage of the furnace to the second input of the comparator block 13, where it is compared with the screen of a current proportional to the current value of the arc current. The error mismatch from the output of the comparator unit 13 is fed to the input of the power amplifier 14, where it is amplified to a certain polarity and transmitted to the executive mechanism 15, which moves the electrode 16 towards the elimination of the disturbance. Voltage isolation unit 6 on the arc is built on the principle of analog voltage selection on the arc from the phase voltage of the furnace. On the first phase of the voltage on the arc i2,. db dii - Чз5Т- 1 Р il,. idt arc stress; phase voltage on the packs own inductance of fae 1 of the secondary current lead mutual inductance between sy and phases 1 and 2; З-за17МН Я inductance between, two phases 1% 3 active resistance of the secondary current lead; currents 3 electrodes; current and electrode from current sensor 1, for example, with transforma ™. The first derivatives of the currents are obtained with the help of sensors for the generation of the first derivatives of current 2 and 3, for example, using Rogovsk

installed in two phases

(1st and 2nd).

The first production of the current of the 3rd phase, defined by the expression

d {3 ii 2

The proposed device for determining the charge collapses using an arc voltage isolation unit on the arc, current effective current isolation units and voltage matching circuit oyrv to obtain information on the operation of 11c is obtained by summing the first derivatives of the 1st and 2nd phase currents in the sensor 4, for example , on an operational amplifier. The values of Lj.M, 2, HELL 13, are determined by the calculation-experimental method for a specific furnace installation. The signals taken from current sensor 1, sensors 2, 3, 4 of the first arc current produced by time and phase sensor 5: voltage (according to expression l) are fed to the inputs of voltage extraction unit 6, an arc made, for example, the operational amplifier, the output signal of which is proportional to the voltage on the arc and is fed to the input of the block 7 for the selection of the effective voltage value on the arc. The signal from the output of the active voltage value extraction unit 7 at the arc is supplied to the first input of the coincidence element 8, to the second input of which a signal proportional to the actual arc current value is taken from the output of the active current arc current selection value 12. During the charge collapse, when the arc voltage is equal to zero, and there is no current signal, the input of the coincidence block, at its output appears, which after a certain time delay effected by time relay 9 is fed to the input of the comparison block 13 and at its output a mismatch signal appears, which is amplified by power amplifier 14 and with a certain polarity transmitted to the actuator 15, lifting the electrode 16 and leaving it from the charge collapse. At the same time, the signal from the time relay outputs 9 is fed to the inputs units of comparison of regulators of other phases, similarly lifting the electrodes of these phases, thereby preventing them from possible breakage when the charge falls. The time delay is determined for a specific furnace installation, taking into account the permanent time of the system's eletants / tents, and is necessary so that short-term operational short-circuits in one phase do not drive the electrodes of all phases upwards and simultaneously short-circuits to accurately determine the charge falls. Raising the electrodes of all phases at the same time prevents their possible breakdown, since when a single electrode leaves the landslide, falling pieces of the salt can cause breakage of the electrodes under which the arcs are heated. The use of the specific current level of the arc current as the informative parameter of the falls of the charge cannot provide accurate information about the collapses of the charge, since the resistance of the charge varies during melting, depending on the chemical composition and decomposition of the electrodes. Transient resistance also varies during smelting. Therefore, the operational short-circuit currents will be different during the period of the melting of the water, which makes it difficult to determine cocTOSi or the charge collapse. And the arc voltage equal to zero, with an operational short trip and the presence of current in the phase, precisely determines the state of the charge collapse. Reduction of electrode breakages reduces their specific consumption, stoppages of the furnace and increases the technical and economic performance of the furnace. For example, by reducing the breakdowns of electrodes on a DSP-200 furnace, the consumption of electrodes per ton of steel produced can be reduced from 7.5 to 6.5 kg / ton. With an electrode cost of 500 rubles per ton and a furnace productivity of 250 Too per year, the economic effect will be 125 Too rub. in year. 75 Form ate and Automatic control of the power of an arc three-phase electric-3; containing for each phase the arc current and phase voltage sensors) {shed, connected respectively to the allocation units of the effective arc current value and the effective phase voltage value, connected to two Comparative power unit, the output of which is connected to the actuator through the amplifier & Electrode compartment, characterized in that, in order to increase the reliability of the furnace to prevent electrode breakdowns during charge collapses, it is provided for each phase with an arc voltage detecting unit, which can be output through the effective arc voltage extraction unit to the first input the newly introduced coincidence element, connected by the second input to the unit with the active arc current value, and output via the time relay to the additional outputs of the comparison blocks of all phases. Sources of information taken into account in the examination 1. G. Farnasov, Avts {attribution of the processes of electric smelting of steel, Metals Mining, 1972, p. 84-93, 2. Author's certificate of the USSR No. 559471, cl. G 05 F 1/66, 1974.

Claims (1)

An automatic power regulator for a three-phase electric arc furnace, containing for each phase arc current and phase voltage sensors connected respectively to the units for extracting the effective value of the arc current and the effective value of the phase voltage connected to two inputs of the comparison unit, the output of which is connected via an amplifier with an actuator placement of the electrode, characterized in that, in order to increase the reliability of the furnace by preventing breakdown of the electrodes during collapse of the charge, it is equipped for each the phase by the arc voltage detecting unit, the output of which through the block for selecting the effective voltage value for the arc® is connected to the first input of the newly introduced coincidence element connected to the second input to the block for selecting the effective voltage of the arc current, and the output through the time relay to the additional inputs of all comparison blocks phases.