SU1364906A1 - Multichannel temperature-measuring device - Google Patents

Abstract

The device is designed to measure the temperature fields of an object using thermocouples, while calibration and calibration of measuring channels (IR) are performed without disturbing their integrity under actual operating conditions. The purpose of the invention is to improve the measurement accuracy while simultaneously increasing the number of measurement channels. The device consists of n identical IR temperatures and g channels of generation of gauge (L

Description

night signals. Each IR consists of a thermocouple 1, a resistive divider 2 and a measuring amplifier 3 connected in series with it. Each of the g channels for generating a calibration signal includes a filter 5, a demodulator 6, and one of the g + 1 windings of the isolation transformer 8. Connecting the output channels calibration signals to resistive dividers in the input circuits of the infrared are carried out simultaneously through the group switch 4. To control the modulator, the device contains trigger 10 and generator 11. When the device is in operation for calibration time and control, the group switch simultaneously connects the outputs of the channels generating the calibration signals to the resistive dividers, and the source of the reference voltage generates voltage levels corresponding to the calibrated IR scale points. After the calibration of this group is completed, the next group is connected to the IR, and so on. I il.

The invention relates to a measurement technique, namely to multi-channel temperature measuring devices using thermocouples, in which electrical calibration of measuring channels is carried out before measurements or their metrics are determined. Role characteristics during calibration and certification.

The purpose of the invention is to increase the measurement accuracy while simultaneously increasing the number of measuring channels.

The drawing shows a diagram of the proposed device.

The device contains n identical measuring channels, each of which consists of a thermocouple 1, a resistive divider 2 and measuring amplifier 3, the output of which is connected to recording equipment or input devices in the computer. The group switch 4 is shown, g channels of generating calibration signals, each of which consists of a low-pass filter 5, a demodulator 6, a secondary winding 7 of a transformer 8, a modulator 9, a trigger 10, a generator

11, secondary feedback winding 12, filter 13, demodulator 14, differential amplifier 15, reference voltage source 16.

Thermocouples 1 are connected via resistive dividers 2 to measuring amplifiers 3. Resistive dividers are connected to the outputs of switch 4,

0

five

R

five

0

0

the inputs of which are connected to filters 5. Filters 5 are connected via demodulators 6 to the secondary windings 7 of transformer 8. The primary winding of the transformer is connected to modulator 9 connected via trigger 10 to generator 11. Output 16 of the sample voltage is connected to a non-inverting input the differential amplifier 15, the inverting input of which is connected through the filter 13 and the demodulator 14 to the secondary feedback winding 12, and its output is connected to the midpoint 17 of the primary winding of the transformer.

I

It is advisable to use an operational amplifier as a differential amplifier 15, and demodulators 6 and I 4 to perform them in the form of synchronous detectors on integrated breakers. A possible implementation of the modulator 9 is to build it on the basis of a transistor full-wave modulator. Group switch 4 can be both contact and contactless. Its specific implementation depends on the total number of measuring channels n and on the number of channels for generating calibration signals g. For n 100, a switch can be made up of g commercially available switches, for example, type F7100, F240, etc. To ensure equality of output calibration signals, it is necessary to achieve identical performance channels of

calibrating voltages, and in the manufacture of a transformer - apply multifilter winding.

When the device is in operation for calibration and control, the group kOhm mutator simultaneously connects filter outputs to r from thermistor pairs of resistor dividers, the source of exemplary voltage generates voltage levels corresponding to the calibrated points of the scale of the measuring channel. After the calibration of this group of measuring channels is completed, the following r resistive dividers are connected, etc. Group Switch and Reference Voltage Management

It is advisable to entrust the computer.

I-

The time required to calibrate or monitor all measuring channels can be estimated according to the expression

T.

k m

de k is the number of tests at one point of the scale of the measuring channel;

the number of points of the scale; the number of measuring channels; settling time of the output signal of the measuring channel; g - the number of measuring channels.

m p With

the outputs of which are simultaneous dividers of measuring channels.

but a calibration signal is applied.

Claims (1)

Invention Formula A multichannel temperature measuring device containing a thermoelectric converter included in each channel, a resistive divider and a measuring amplifier, a source of reference voltage, a series-connected auto-oscillator, a trigger, a modulator and a transformer whose primary winding is made with a midpoint and connected to the output torus demodulators-detectors connected individually to secondary windings transformer, and low-pass filters included at the output of demodulators-detectors, characterized by the fact that, in order to improve the measurement accuracy while increasing the number of measuring channels, a group switch and a differential amplifier are introduced into it, the inverting input of which is connected to the output of one of the lower filters frequency, its non-inverting input is connected to the output of an exemplary voltage source, and its output to the midpoint of the primary winding of the transformer, while the outputs of other low-pass filters are connected to the inputs of a group switch, the outputs of which are connected to resistive