JPH1123503A - Soil thermal resistance measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve trouble that a worker reads and calculates the measured temperature at each measurement by incorporating a heating means and a temperature measuring means in a probe body buried in soil, and providing a means calculating and displaying the soil resistance from the measured temperature. SOLUTION: A probe body 1 driven into soil is provided with a heater 2 and a thermocouple 3 detecting the temperature of the probe body 1 by the heater 2. The base end of the probe body 1 is integrated with a pedestal 5, and the pedestal 5 is provided with the terminal 6 of the thermocouple 3 and the terminals 7 of the heater 2. The terminal 6 is connected to a temperature measurement section 8, and the terminals 7 are connected to a heating power supply 9. The temperature measurement section 8 is constituted of an input means of a set value, a means calculating the soil inherent thermal resistance from the set value and the measured temperature of the thermocouple 3, and a display means displaying the calculated result. The probe body 1 is driven, and the heater 2 is carried a current for heating. The temperature of the probe body 1 is measured for 20 min, for example, and the soil inherent thermal resistance is automatically calculated from the measured result and is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring instrument for measuring soil specific thermal resistance.

[0002]

2. Description of the Related Art Since the power transmission capacity of a power cable is greatly affected by the thermal resistance of the soil around which the cable is buried, it is necessary to know the soil specific thermal resistance of the cable laying route as one of the basic materials for cable design. is there.

[0003] To measure the specific thermal resistance of the soil, a probe bar having a heat source and a temperature measuring means is inserted into the soil, and a temperature change when the heating is performed by the heat source for a predetermined time is measured by the temperature measuring means. Is used to calculate the thermal resistance.

[0004]

However, in the above-described measurement technique, heating by a heat source, recording of a temperature change, and calculation of soil specific thermal resistance must be performed for each measurement, and the work is complicated.

[0005]

SUMMARY OF THE INVENTION The soil resistance measuring instrument of the present invention solves the above-mentioned problems, and is characterized by a probe body embedded in the soil, a heating means built in the probe body, It comprises means for measuring the temperature of the probe main body, means for calculating the soil thermal resistance from the measured temperature, and means for displaying the result of the calculation.

Here, the calculation of the soil specific resistance value g is preferably performed by the following equation. g = {(4πL) / (2.303)} × ｛(θ20−θ
2) / (W)｝ g: soil specific thermal resistance (° C. cm / W) L: length of probe body (cm) θ20: temperature for 20 minutes after heating (° C.) θ2: temperature for 2 minutes after heating ( ° C) W: Power consumption (w)

[0007]

Embodiments of the present invention will be described below. FIG. 1 shows an outline of the measuring instrument of the present invention. The measuring instrument of the present invention includes a probe main body 1 driven into the soil, a heater 2 (heating means) built in the probe main body 1, and a thermocouple 3 (temperature measuring means) capable of detecting the temperature of the main body by the heating means. Equipped. The probe main body 1 is made of, for example, a copper pipe, and the tip is formed in a tapered shape so as to be easily inserted into the soil. The heater 2 is a long one that can heat the main body 1 over substantially the entire length, and uses, for example, a nichrome wire. The nichrome wire is inserted into the main body, and an insulating material 4 is filled between the main body 1 and the nichrome wire. Further, the thermocouples 3 are embedded in the main body 1 so as to measure the temperature at three points in the longitudinal direction of the main body 1. In this example, a groove was cut in the main body 1 and three thermocouples 3 were installed therein and embedded with an insulating material. The interval between the thermocouples 3 is 250 mm.

The base end of the main body 1 (on the side opposite to the front end)
Is integrated with the pedestal 5, and the pedestal 5 has terminals 6 of the thermocouple.
And a heater terminal 7 are provided. The terminal 6 of the thermocouple is connected to the temperature measuring unit 8, and the terminal 7 of the heater is connected to a power supply 9 for heating. The main components of the temperature measuring unit 8 are a set value input unit, a unit for calculating the soil specific thermal resistance from the set value and the measured temperature of the thermocouple, and a display unit for displaying the calculation result. .

In order to obtain the soil specific thermal resistance using such a measuring instrument, first, a guide rod having substantially the same dimensions as the main body 1 is driven into the soil to form a guide hole, and the main body 1 is driven there. Next, the heater 2 is energized to heat the main body 1. Then, the temperature of the main body 1 is measured for, for example, 20 minutes, and the soil specific thermal resistance is obtained from the measurement result by the calculation described below.

For the calculation, for example, the measured temperature two minutes after the heating and the measured temperature 20 minutes after the heating are used. These measurement temperatures at each measurement point of the thermocouple 3 are measured by the temperature measurement unit 8.
Is stored in the storage means. Further, the following equation for calculating the soil specific thermal resistance is stored in the storage means of the temperature measuring unit 8 in advance. g = {(4πL) / (2.303)} × ｛(θ20−θ
2) / (W)｝ g: soil specific thermal resistance (° C. cm / W) L: length of probe body (cm) θ20: temperature for 20 minutes after heating (° C.) θ2: temperature for 2 minutes after heating ( ° C) W: Power consumption (w)

[0011] Of the variables in this equation, L and W are obtained from the specifications of the measuring instrument, and thus the values may be input from the input means of the temperature measuring section 8 as set values and stored in the storage means. The soil specific resistance value is obtained by reading out θ20, θ2 and the set value for each thermocouple from the storage means and calculating by the above formula. Further, the specific thermal resistance of the soil obtained based on the three measured temperatures is averaged by the calculating means, and the average value is displayed on the display means as the specific thermal resistance of the soil.

As described above, according to the measuring instrument of the present invention, the measuring instrument automatically calculates and displays the soil specific thermal resistance, so that the soil specific thermal resistance value can be immediately known.

[0013]

As described above, according to the measuring instrument of the present invention, the soil specific thermal resistance value can be automatically obtained, so that the trouble of the operator reading and calculating the measured temperature for each measurement can be eliminated. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a soil thermal resistance measuring device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 End needle main body 2 Heater 3 Thermocouple 4 Insulation material 5 Pedestal 6 Terminal of thermocouple 7 Terminal of heater 8 Temperature measurement part 9 Heating power supply

Claims (1)

[Claims] 1. A probe body embedded in soil, heating means built in the probe body, means for measuring the temperature of the probe body, means for calculating the soil thermal resistance from the measured temperature, Means for displaying the calculation result.