SU744501A2 - System for automatic regulation of temperature - Google Patents

Description

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The invention relates to temperature control systems using temperature-sensitive elements whose electrical or magnetic properties are temperature dependent. It can be used to control the temperature regime of high-gap electric resistance furnaces with the recording of the adjustment process on the diagram.

According to the main author. St. No. 487382 is a known automatic temperature control system, used primarily for temperature control of electric furnaces. This system contains a nonentiometer with a differential-lever mechanism for setting a task, a phase-shifting device, a pulse shaper, an inductance coil and a magnetic core, the movable part of which is connected to the stem of the differential-lever mechanism for setting a nomentiometer, and an inductor is located on the fixed part, connected through a phase-shifting device with the input of the pulse shaper.

The known system allows non-contact phase temperature control in electric resistance furnaces with the recording of the control process, however, it does not provide quality control of the temperature mode of multi-zone electric furnaces, b it does not provide for correction of the value of the input power and simultaneous temperature control

5 in each zone of a multi-zone industrial electric furnace, which limits the functionality of a known system.

The aim of the invention is to expand the field of application of the system by providing control of the temperature regime of multi-furnace electric furnaces with correction of the value of the input power in each zone. The goal is achieved by the fact that

15 phase correction devices are introduced into the proposed system, respectively, according to the number of zones of the electric furnace and additional impulse drivers, and the output of the phase shifter is connected to

20 inputs of pulse shapers through phase-correcting devices.

The drawing shows a schematic diagram of the proposed system.

The system contains a potentiometer 1 with a differential lever-setting mechanism for setting a reference and a small displacement transducer in the form of an inductor with a magnetic core, a phase-shifting device 2 connected to a phase-matching 30 with a rectifying device 3. In the diagram

three phase-correcting devices are shown (by the number of zones of the electric furnace), which are made, for example, in the form of waiting multivibrators with adjustable relaxation time. The outputs of the phase-correcting devices are connected, respectively, through the pulse shaper 4 to the thyristors 5 of each zone of the electric furnace 6, in which the thermocouple 7 is installed.

By means of phase-correcting devices, during the test of an electric furnace, one-time (once) manual correction is made of the magnitude of the input power by decreasing or increasing the thyristor switching angle. Thus, the (initial) alignment of the temperature fields in each zone is performed once, and in some cases, the temperature gradient is created over the zones.

The operation of the automatic temperature control system in multi-zone electric furnaces is as follows.

Until the work is started, the moving brush of the differential-lever mechanism of potentiometer 1 does not affect the displacement transducer in the form of an inductance coil. From the output of the phase shifter 2, a signal is removed with zero or close to zero phase shift. This signal is simultaneously applied to all (in the example shown to three) phase-correcting devices 3. From the output of phase-correcting devices 3, the signal is sent to the corresponding pulse shapers 4 of the thyristor control 5 in each zone of the electric furnace 6. Thus, when the operating condition of the thyristors reaches 5 each zone is maximum and the power input is maximum.

At the setpoint of the controlled temperature, the movable brush of the differential lever mechanism for setting the potentiometer 1 acts on the movable part of the displacement transducer. From the output of the phase-shifter 2, a signal is removed, shifted along

phase at some angle. This signal passes through the phase-correction device 3 and the formers 4 of the thyristor control pulses 5 in each zone of the electric furnace 6. The phase-correction devices 3 manually correct the phase angle, i.e., the input power, if the temperature in the zones differs from the set one. In this way, the gradient of temperatures is zoned.

In some cases, on the contrary, it is required to obtain a certain gradient of the temperature field in the volume of the electric furnace 6 over the zones

which is also carried out by manually correcting the value of the power input by zones.

After aligning or setting the temperature field gradient by zones, the temperature control is carried out simultaneously in all zones of the electric furnace 6.

Introduction to the known system of phase-correcting devices 3 by the number of zones

electric furnace 6, connected in series with the phase-shifting device 2, by selecting the optimal value of the input power in the zone, significantly improve the quality of regulation and reduce

amplitude of temperature fluctuations at a given level to a minimum (± 2-3 ° C).

The use of the additional invention expands the field of application of the known system and improves the quality of temperature control of multi-zone electric furnaces.

Claims (1)

Invention Formula Automatic temperature control system according to aut. St. No. 487382, characterized in that, in order to expand the scope of application, it contains phase-correcting devices and additional pulse shapers, with the output of the phase-shifting device connected to the inputs of the pulse shapers through phase-correcting devices. jEf