SU960763A1 - Device for checking thermocouple serviceability - Google Patents

Description

(54) DEVICE TO CONTROL THERMOPOOR CORRECTIONS 12

The invention relates to the control of automatic control and regulation systems and can be used in electrical temperature controllers in which a thermocouple is used as a measuring transducer.

Thermocouple control devices are known that contain a thermocouple and means of amplifying, indicating, and converting the signal C.

A disadvantage of the known device is the complexity of the design consisting of a single-shot, keys, resistive dividers, a comparing differential amplifier and output triggers.

The closest to the invention in its technical essence is a device for monitoring the thermocouple operability, containing a positive-current amplifier connected to a power source, with an alarm in the output stage of which is connected, and a sensor is connected to the input of amplifier 2.

However, in devices e, due to the galvanic coupling of the input circuits of the amplifier, for the purpose of the thermocouple, false signals can be detected in the control channel. Feedback in this; device is complicated.

The aim of the invention is to increase the reliability of the device.

The goal is achieved by the fact that in the device for monitoring the operability of the thermocouple containing the amplifier

10 DC with positive feedback, positive feedback is made in the form of two series-connected capacitors, the common point of which is connected

15 with a power supply bus through a controlled thermocouple.

The amplifier is constantly:; a positive feedback current represents a pulse generator.

Claims (2)

This embodiment of the device allows for both | ve thermocouple circuit transfer previously inhibited pulse generator to the generation mode pr 25; coal impulses of a given borehole, which makes it possible to carry out flashing signaling. When the thermocouple circuit is restored, the flashing alarm automatically stops. The drawing shows a schematic diagram of a PPS device. The pulse generator 1 is a two-stage amplifier of direct current on transistors 2 and 3 of different types of conductivity with positive feedback on capacitors 4 and 5 and the basic voltage divider on resistors 6 and 7 and diode 8. LED 9 is included in the collector circuit. transistor 3 and is a signaling device. Thermocouple 10 is connected to a common point of capacitors 4 and 5. The collector loads of transistors 2 and 3 are resistors 11 and 12. The device operates as follows. In the case of a closed circuit of thermocouple 10, when the power is turned on, capacitor 5 is an instantaneous resistance, as a result of which transistors 2 and 3 open. At the same time, the charge of the capacitor 5 along the circuit begins: n / 1us of the current pstani resistor 11, junction-emitter - base of the trans-, eistor 2, thermocouple 10, minus the power supply. When charging the capacitor 5 to the threshold level determined by the base divider, the transistor 2 closes, the supply circuit of the transistor 3 of the transistor 3 is broken, therefore the transistor 3 also closes. The process is an avalanche-like process, since the circuit of the positive OS is shunted by the low resistance of the thermocouple 10, the device is in a steady state. The capacitor 4 through the resistor 12, the LED 9 for a short time from 1p to the voltage of the power source. When the thermocouple circuit 10 is broken, positive feedback is restored in the DC amplifier and capacitor 5 is recharged with energy accumulated by capacitor 4 to the threshold of opening transistor 2. Transistor 2 goes into active mode, degrades saturation of transistor .3, LED 9 emits a pulse of light, the duration of which is determined by the charging time of capacitors 5 and 4 to the threshold of locking transistor 2, since transistor 2 does not translate above the collector potential of transistor 3, zara capacitors 5 and 4 There are n circuits: plus power supply, resisto, 11, emitter junction - base of transistor 2, junction source transistor 3, minus source - before locking transistor 2 and 3. After this, recharging of capacitors 4 and 5 along the circuit begins: plus source power supply, resistor 12, LED 9, capacitors 4 and 5, diode 8, resistor, minus the power supply - until the transistor 2 is opened. The process repeats by flashing signaling. When restoring the thermoelectric circuit, 10 and the transistors are locked, LED 9 extinguished, generator 1 turns are in DC amplifier with trapped transistors 2 and 3, almost no energy is consumed from the power source. The device is characterized by reliability. Since the thermocouple is usually located in the control object, in actual conditions at its ends a signal from the power circuits appears. In the proposed device, it is possible. The false alarm rate is reduced to a minimum, since this requires a negative interference signal, commensurate with the charge potential of the capacitor 5, which is slightly lower than the supply voltage. The invention improves the reliability of the controller, eliminates the harmful effects of the device on the circuit. temperature measurement and control; and the effect of the thermocouple EMF of the thermocouple on the device itself. Thermocouple control. Insulation is advisable to use in devices for controlling and measuring temperature and other technological parameters in which low-resistance sensors are used. Claims of the Invention A device for monitoring the operability of a thermocouple containing a DC power amplifier with a positive feedback connected to a power source, with an alarm indicator connected to the output stage, in order to increase the reliability of the device, in it a positive feedback is performed in the form of two series-connected capacitors, the common point of which is connected to the power supply bus through a controlled thermocouple. Sources of information taken into account in Examination 1. US Patent 3,973,184, CL.324.51 published. 1976. 2. Ilyinsk LA Elements of fire automatics. M., Energie, 1969, p. 66 (prototype). 1 f