SU759967A1 - Thermotransducer - Google Patents

Description

The invention relates to the field of electrical measuring equipment and can be used for simultaneously comparing the four electrical variables of alternating or direct current and their combinations, in particular, for simultaneous comparing the capacities of alternating and direct current, at the same time.

Thermoconverters are known that contain a heater in the housing that has thermal contact with a thermocouple made of an alloy chromel-copel £ ΐ].

However, they have low conversion accuracy and a considerable scatter of $ 1 current-voltage characteristics, which complicates their use in simultaneous comparing circuits, and reduces the performance of the simulator. .

The closest in technical '20 essence to the proposed are multi-element thermocouples containing 40 sequentially connected. chromel copel thermocouples, whose hot junctions are heated by 25 two heaters arranged parallel to each other. Thermocouples and heaters are mounted in a copper casing that stabilizes the temperature of the cold ends of thermocouples [2130

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However, for the power to be compared by the method of equal temperatures, two transducers are needed for power measurement, the identity of the current-voltage characteristics of which is achieved by sampling from a batch of converters or by artificial equalization, which reduces the frequency band, accuracy, reliability and production. water measurement.

The purpose of the Invention is to improve the accuracy of conversion and measurement performance.

This is achieved by the fact that in the thermal converter, which contains a housing with four non-heated heaters and a thermoelement, are identical. Heaters are placed in pairs perpendicular to each other, and sections of heaters that include their point of intersection have thermal contact with. ends of a thermoelement equipped with a contactless heat sink With two degrees of freedom of movement.

FIG. 1 shows the proposed thermocouple) in FIG. 2 shows the arrangement of the elements in the housing 'in FIG. 3 given electrical circuit measurements.

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The ’thermopregeator (FIGS. 1, 2) in the copper case 1 contains four identical heaters 2,, 2 ^ and 3 ,,

3 ₂ , arranged in pairs perpendicular to each other, i.e. heater 2, intersects at a right angle with heater 2 ₂ , and heater

with heater 3 ₂ . The sections of heaters 2, and 2у, 3, and 3 ^, including the point of their mutual intersection, have thermal contact 4, and 4 ₂ with the ends of the semiconductor differential. thermoelement 5, for example from C85b. Heaters 2 ₄ , 2 ₂ and 3-g, 3 ₂ and thermoelement 5 are connected to a thermostat. a bilised part of the leads 6 (for example, from a silver microwire), which through thermally conductive electrical insulation 7 (for example, beryllium oxide) have thermal contact with the housing 1 and the gaskets 8, made of a material with high thermal conductivity, for example copper.

The thermostatted part of the b terminals of the heaters and the thermocouple 5 of the converter is connected to the external switching leads 10 of the electrical insulating plate 11 by means of mounting leads 9, which serve as thermal shutters. Above the thermoelectric element 5 there is a contactless heat sink 12 with two screws 13 and 14. With the heat sink 12 and screws 13 and 14, the correction of the steepness of the current-voltage conversion characteristics of hot junctions contacts 4 _η , 4 _Ζ thermoelement 5, i.e. Adjustable by contactless change of heat exchange conditions; the identity of the conversion according to the four inputs of the converter.

Thermocouple works as follows. Heaters 2-, 2% and 3 ,, 3 _{2 are} connected in series into a DC or AC circuit and regulate the screws 13 and 14 to the absence of a thermal voltage at the output of the converter. Then include heaters 2 ₁ , 2 ₂ and З _l , 3 ₂ in the sum-difference scheme of power measurement (Fig. 3), i.e. serves to the four inputs of this circuit signals AC 3 ". and ΙΜ. and DC 3- and ₌ , the power of which must be compared. Then, by a heater, for example 2-, current flows ΐ ₂ = (μ + _[Tse, and for the heater 2% -. Ϊ́ ₂ = ~ _3ιν -! 1 _uA, which by separating them, Hea $ 1a- Joule heat the contact 4 · thermoelement 5, which leads to the appearance in it of thermo-emf (1

where is the conversion factor

contact junction 4.

Simultaneously on the heaters Z _lp

3 £ flow tokig ^ -. Y ^; and

who warmed up the junction (contact)

4 _L thermoelement 5, in connection with which

it arises thermo-emf /;

PE ,, GN1 /

(2)

where is the conversion coefficient of the contact 4 ^.

Thermocouple 5 included differentially so thermo emf Ε _ΤΠι oppositely directed thermo emf E _mp, in connection with which the inverter output is valid difference thermo emf

Given that the current-voltage characteristics of the converter are identical, then K = Κ _Ί. Then, on the basis of expressions (1), (2), (3) after, the expansion of brackets and simple transformations we have

where ⁽⁴⁾

respectively, the power signals of DC and AC.

From the expression (4), it can be seen that the output thermo-emf of the converter is proportional to the difference between the compared powers of the signals of direct and alternating current. · Regulating the signals 3-,

11- DC to the absence of a thermo-EMF at the output of the converter (E = 0) and measuring the values of the signals Cc and _{x by} one of the known methods (for example, a DC compensator), judge the value of the measured power P ^, the signals of alternating current Cx. and ΙΙχ ,.

Thus, the presence in the proposed thermocouple four identical heaters and differential thermoelement allows simultaneous comparing AC power with a known constant power or simultaneous comparing four other electrical quantities AC or DC, or combinations thereof, which increases the measurement performance. The contactless corrector of the current-voltage conversion characteristics and the pairwise perpendicular arrangement of the heaters practically do not increase the capacity between the heaters and the thermoelement, which makes it possible to increase the identity and accuracy of the conversion in a wide frequency range.

In addition, when measuring with the proposed transducer, the mode of equal temperatures is automatically performed, and when operating at one point, the mode of constant temperatures, which ensures the greatest accuracy of measurement.

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Claims (1)

Claim ! A thermal converter containing a housing with heaters located in it and a thermoelement, characterized in that, in order to improve the conversion accuracy and performance, four identical heaters are arranged in pairs perpendicular to each other, and heater sections that include their mutual intersection point have a thermal contact with the ends of a thermoelement equipped with a contactless heat sink with two degrees of freedom of movement.