KR900000247B1 - Measuring instrument of thermometer - Google Patents

Abstract

A temperature compensation leading wire and temperature measurement selection SW(SW1-SWn) wires from a thermocouple connector (65) are connected to a temperature indicator (TI). Cold junction thermocouples (A1-An) and a copper wire (61) are connected to a reference junction box (RJ) in which the temperature is uniform. The electrical error occuring at the junctions are to be eliminated by making the e.m.f. indicated by the TI according to the selection of the SW(SW1-SWn) to be equal to the e.m.f. generating at the thermocouples.

Description

Temperature measuring device using reference junction box for multi temperature measurement

1 is a basic circuit diagram measured with a temperature indicator using a thermocouple.

2 is a basic circuit diagram using a bolt meta as a thermometer using a thermocouple.

3 is a circuit diagram of a cold junction compensation principle.

4 is a multipoint temperature measurement circuit diagram in the use of a conventional data acquisition device.

5 is a multipoint temperature measurement circuit diagram in the use of a conventional temperature indicator.

6 is a circuit diagram according to the present invention.

7 is an external view of the reference junction box according to the invention.

8 is a basic circuit diagram using a temperature indicator according to the present invention.

9 is a basic circuit diagram using the bolt meta according to the present invention.

* Explanation of symbols for main parts of the drawings

61 copper 62, 65 connector,

66: cold junction compensator SW1-SMn: temperature measurement selector switch

TI: Temperature indicator RJ: Reference point box

# 1- # n, A1-An,: Thermocouple

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature measuring apparatus using a thermocouple, and in particular, to connect a thermocouple and a copper wire in a reference junction box with an equal temperature and generate a temperature indicator by the same thermocouple. Temperature measurement using the reference junction box for multi-temperature measurement, which can accurately indicate the measurement temperature by correcting the electrical error generated from the reference junction box on the line connected to the thermometer by equalizing the force generated in the thermocouple and the thermocouple. Relates to a device.

In general, the electrical material for temperature measurement may measure temperature using a change in electrical resistance due to temperature change, or thermoelectric power between dissimilar metals.

The thermocouple material is an electrical material for temperature measurement, which is described in detail on principles, properties, and materials in pages 108-112 of "Electric Materials" published by "Bosung Cultural Company."

Conventionally used thermocouples measure the electromotive force generated regularly according to temperature change when two different internal tissues attach wire ends of metal and alloy of uniform material to each other, and then convert them into temperature values. The temperature has been measured.

Examples of the type of thermocouples that are widely applied are shown in Table 1 below.

Common application methods for measuring temperature using the thermocouple include the methods shown in FIGS. 1 and 2.

In the case of FIG. 1, when V is the instrument indicator arm, VT is the thermocouple electromotive force, VTA is the electromotive force generated at ambient temperature, and VIR is the correction voltage (corrected according to the change of the ambient temperature) inside the thermometer. Electromotive force (VT)-Electromotive force (VTR) generated at ambient temperature + Correction voltage (VTR) inside the thermometer corrected according to the change in ambient temperature

The temperature measured value can be obtained by Equation (1), where the instrument voltage V becomes the thermocouple electromotive force VT when the atmospheric temperature TA and the correction voltage T1 are the same.

In the case of FIG. 2, the symbol names of V, VT, VTA, and VIR are the same as those of FIG. Emissions from Temperature (VTR) … (2), becomes.

Since the temperature in the reference junction box RJ must be maintained at 0 ° C. when it is established as shown in Equation (2) and uses a voltmeter (Voltmetor) as a thermometer, the atmospheric temperature TA becomes zero (0).

Equations (3) and (4) hold, resulting in temperature

Conventionally, when measuring the temperature of various parts as shown in FIG. 4 or measuring the temperature with a data collection device as shown in FIG. 5 or when measuring the temperature in voltmeter, it is necessary for each contact point. As many expensive cold junction compensators were used.

In simple terms, a cold junction is a cold junction that combines two different metals to form a circuit, and if the two junctions are kept at different temperatures, thermal power is generated in the circuit and current flows. Is called the cold junction, and the temperature of the cold junction is usually maintained at 0 ° C. That is, since the voltage drop phenomenon occurs when the thermocouple line is directly in contact with the copper line as shown in FIG. 3, the cold junction compensator adds a voltage corresponding to the change voltage value (VTA) according to the temperature of the junction point, thereby increasing V. = VT has been made.

Accordingly, an object of the present invention is to provide a temperature measuring device capable of compensating an electrical error generated in a reference voltage box in a line connected to a thermometer by connecting a thermocouple and a copper wire in a reference voltage box having an equal temperature.

Another object of the present invention is to provide a temperature measuring circuit having excellent compatibility and reducing measurement error and installation cost according to the type of measurement function. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

6 is a circuit diagram according to the present invention, TH-M'A ', TH-M "A" is a thermocouple dissimilar metal, 61 is copper (Cu), 66 is a cold junction compensator, SW1-SWn is a temperature measurement selection switch , TI is the temperature indicator, RJ is the reference junction box, 62 and 65 are the connectors, # 1- # n is the temperature measuring thermocouple (Hot), and Al-An is the cold junction thermocouple (Cold) in the reference junction box (RJ). Each of the temperature measuring thermocouples (# 1- # n) is connected in parallel to the cold junction compensator 66 and the connector 62, and the cold junction compensator 66 is connected in parallel with the cold junction thermocouple (Al-An). And temperature are selected from one of the temperature measuring thermocouples (# 1- # n) connected to the connector 62 by a temperature measurement selector switch (SW1-SWn) having an on contact and connected to the connector 65 and the connector 65. It is configured to measure, and is configured to indicate the temperature at the temperature indicator (TI) from the contact of the connector 65 and the temperature measurement selector switch (SW1-SWn).

The dotted line indicates the reference junction box RJ, and FIG. 7 is an external view of the reference junction box RJ, 7A is a front view, and 7B is a side cross-sectional view of the reference junction box.

In Fig. 7, A is a thermal insulation material in the reference junction box, B is a sponge for preventing damage and insulation of the terminal board, C is a cold junction compensator for one point temperature compensation, and D is a wire as a terminal block. Connection terminal for connecting, E is a multi-connector, F is a wire coupling, G is a terminal block, cold junction compensator (C) is a reference junction box (RJ) when measuring temperature using a computer or voltmeter Connect thermocouple and copper wire with cold junction compensator to compensate the temperature of cold junction. At this time, it is a "0" contact to compensate for the generated electromotive force, and serves to send the voltage generated from the thermocouple to the copper wire without voltage change, and the temperature compensation circuit may be configured as a general compensation circuit.

The multi-connector (E) is a copper connector for sending to the measurement room, the connector 62 of FIG. 6, the sun coupler ring (F) is a connector connected from the temperature measuring position.

8 is an embodiment using a temperature indicator according to the invention, Figure 9 is an embodiment using the bolt meter according to the present invention. Therefore, a specific embodiment of the present invention will be described in detail with reference to the above-mentioned 6, 7, 8, 9, the present invention uses the basic principle of the thermocouple, the thermocouple and copper wire in a reference junction box of equal temperature Connect it. At this time, the electromotive force indicated by the indicator is equal to the electromotive force generated in the thermocouple by the same thermocouple to correct the electrical error generated in the reference junction box in the line connected to the thermometer. When one is operated, the corresponding temperature can be measured.

For example, if you turn on the temperature measurement selector switch (SW1), you can measure the temperature with the temperature measurement thermocouple (roast), and if you turn on the temperature measurement selector switch (SW2), you can In addition, when the temperature measurement selection switch (SW1) in the off position is not measured by the temperature of any thermocouple can operate the other switch to measure the temperature of the other thermocouple. Therefore, regardless of the position of the temperature measurement selector switch (SW1-SWn), the basic circuit configuration is configured as shown in FIG. 8 of the temperature indicating method, so that the cold junction thermocouple (Al ~) in the 6th and 7th reference junction box (RJ) is included. An) represents the average error in the reference junction box (RJ) because it is connected in parallel.

That is, in FIG. 8, the time-indicating voltage (V) = VT-VTR1 + VTR2-VTA + VIR ... (5) is the same temperature in the reference contact box (RJ) as shown in Equation (5) above, so that VTRI = VTR2 and the temperature of the silver indicator (TEMPIND) and TA are the atmospheric temperature, so V = VT because VTA = VIR.

That is, the temperature measuring thermocouples (# 1- # n) are connected to the contacts in the reference junction box (RJ) with copper wires, respectively, to the connector 62, and the temperature in the reference junction box (RJ) is rka. Connect the contact thermocouple in parallel with (A-An) to sense the average temperature in the reference junction box (RJ), and connect it to the temperature indicators (T1) a and b terminals through the connector 65 to select the switch according to the temperature measurement. By the operation of (SW1-SWn), the temperature of the on-contact thermocouple is measured at each of the measuring thermocouples # 1- # n. The cold junction compensator 66 is not necessary when using the temperature indicator.

If the temperature indicator is used as the voltmeter, the basic circuit configuration is shown in Fig. 9 regardless of the position of the temperature measurement selector switch (SWI-SWn). The correction here may correct the electrical error generated in the reference junction box RJ only through the connection Notel of the connector 62 of FIG. 6. That is, although the electromotive force VAB of the contact point AB of FIG. 9 is VTR2-VTRl + VCR, since the temperature in the reference junction box RJ is the same, VTRI = VCR and VAB = VTR2.

Therefore, meter indication voltage (V) = VT-VT3-(-VAB)

= VT (VT3 = VAB)

Can be used to measure the corrected temperature. When measuring temperature with a computer, a circuit corresponding to the temperature compensation circuit attached to the thermometer should be attached. When using the temperature compensation circuit, the number of contacts is required. Therefore, in the above case, since the measured value is multivolt and there is no atmospheric temperature compensation circuit inside the computer voltmeter, it is configured to use the cold junction compensator 66 to correct it.

Therefore, in order to solve the problem, one additional cold junction compensator may be installed to compensate the calculated voltage generated by the cold junction compensator in the computer and may indicate the actual measured temperature.

As described above, in the case of using the reference junction box without installing individual expensive cold junction compensators according to the thermocouple, it can be widely used in contact boxes having different types of thermocouples. The use of a small temperature wire reduces the error and has the advantage of low installation cost.

Claims (1)

In a silver measuring device using thermocouples (# 1- # n, Al-An), a plurality of thermoelectric materials (# 1- # n) and a cold junction temperature compensator 66 on one side of the lead wire in parallel are connected to a multi-connector ( 62) and the cold junction thermocouple (Al-An) and the other lead wire of the cold junction temperature compensator (66) in parallel to the thermocouple connector (65), and the silver compensation lead wire and the temperature from the thermocouple connector (65). Connect the measurement selector switch (SW1-SWn) with a temperature indicator (TI), and connect the cold junction thermocouple (Al-An) and the copper wire (61) in a reference junction box (RJ) with an equal temperature to select the temperature measurement. According to the selection of the switch (SW1-SWn), the electromotive force indicated by the temperature indicator equals the electromotive force generated in the thermocouple so as to eliminate the electrical error generated at the contact point. Temperature measuring device.

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