JPH0346345Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring the amount of heat generated by a long-axis heating element such as a power cable.

Background of the invention The amount of heat that moves per unit area of one surface per unit time is called heat flow, and the following methods are well known for measuring it.

That is, as shown in FIG. 1, a thermal resistor 200 is placed on the surface of a heating element 100. This thermal resistor 200 (Schmidt belt) is made of rubber, for example, and has a thermal conductivity of λ and a thickness of d. Then, the temperature difference between the front and back surfaces at the center of the thermal resistor 200 is measured, and when the difference is ΔT, the heat flow rate Q is given by Q=λΔT/d per unit area.

However, this method has a high risk of disturbing the heat flow, and is not suitable for high-precision measurements or for measuring minute amounts of heat such as those in power cables.

The object of the present invention is to provide an apparatus for measuring the amount of heat generated by a long-axis heating element, which solves the above-mentioned problems.

Structure of the device and its explanation (Figures 2 and 3) The feature of the device is that the long-axis heating element 1
0 is surrounded by a cylindrical thermal resistor 20 with a gap 22 between them; a plurality of differential thermocouples 30 are attached to the thermal resistor 20, and one contact 32 of each is attached to the surface of the other contact. The differential thermocouples 30 are embedded uniformly in the circumferential direction so that the thermocouples 34 are located on the inner surface, and the differential thermocouples 30 are connected in series.

10 indicates a heating element along the long axis.

A heat resistor 20 is made of an insulator such as FRP or rubber. Further, this is made of a cylindrical body surrounding the heating element 10 (it may be divided into two). Further, its inner diameter is somewhat larger than the outer diameter of the heating element 10, so that a gap 22 is formed between the heating element 10 and the heating element 10.

The differential thermocouple 30 has traditionally been used to measure minute temperature differences, and instead of setting a reference temperature junction like a general thermocouple, both junctions are placed at the position where the temperature difference is to be measured. They will be installed in each location. In this case, one contact 32 is embedded in the surface of the thermal resistor 20, and the other contact 34 is embedded in the inner surface of the thermal resistor 20.

Further, a large number of differential thermocouples 30 are embedded in the longitudinal center of the thermal resistor 20 at positions going around the circumferential direction, for example, as shown by dashed lines 40 in FIG. Also these differential thermocouples 30
are arranged uniformly (at equal intervals) in the circumferential direction and connected in series. Note that 50 indicates a measuring device (DC potentiometer).

In addition, all the differential thermocouples 30 may be connected in series, or they may be divided into each row (the row indicated by the dashed-dotted line 40 has only 40, and the row indicated by the dashed-dotted line 42 has only 42). , each column may be connected in series.

Furthermore, each row may be divided into a plurality of blocks in the circumferential or radial direction.

By dividing the differential thermocouple 30 into a plurality of blocks in this way, it becomes possible to measure the distribution of heat flow in the axial direction or circumferential direction of the long-axis heating element 10.

In addition, the heat flow rate Q per unit length of the heating element 10
is the thermal resistance of the thermal resistor 20, Rth is the thermal resistance of the thermal resistor 20, and the differential thermocouple 3 is
If the number of serially connected thermocouples 30 is N, and the sum of temperatures detected by all the differential thermocouples 30 is ΔTi, then in one block in one axial row and column, Q=ΔTi/N Rth.

Effects of the invention A large number of differential thermocouples 30 are uniformly embedded in the cylindrical thermal resistor 20 surrounding the long-axis heating element 10, and they are connected in series, and the heating element 10
A gap 22 is formed between the heat resistor 20 and the heat resistor 20, and this serves to make the heat flow uniform, so that precise measurements can be made without disturbing the heat flow.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the prior art, FIG. 2 is an explanatory diagram of the position where a differential thermocouple is embedded, and FIG. 3 is an explanatory diagram of a cross section at the embedded position of the differential thermocouple. 10: heating element, 20: thermal resistor, 30: differential thermocouple.

Claims (1)

[Claims for Utility Model Registration] (1) A long-axis heating element 10 is surrounded by a cylindrical thermal resistor 20 with a gap 22 between them; The differential thermocouples 30 are embedded uniformly in the circumferential direction, with one contact 32 located on the surface and the other contact 34 on the inner surface, and these differential thermocouples 30 are connected in series. and
A device for measuring the amount of heat generated by a long-axis heating element. (2) An apparatus for measuring the amount of heat generated by a long-axis heating element according to claim 1 of the utility model registration, characterized in that the differential thermocouple 30 is divided into a plurality of blocks.