Control Panel Cooling units Technical Information
3-6. Relationship between electrical resistance and temperature
(1) Electric resistance that changes with temperature.
There is a big difference between general air conditioners and precision air conditioners.
Electric resistance changes with temperature.
Electric resistivity (R《Ω》) changes depending on the temperature and also expresses the formula below.
R(T)=ρ(T)d/S…⑦
ρ(T) is approximately expressed by the following formula near room temperature, By using this formula, the change in electrical resistance with temperature is able to be calculated.
ρ(T)=ρ(T0){1+α(T-T0)}…⑧
※α[10-3/℃] is defined as the temperature coefficient of resistance, the temperature coefficient of T0 is in the table below.
The table below shows the resistivity and temperature relationships of typical materials.
Comparison of general air conditioning and precision air conditioning
It can be considered that the temperature change will be from 17 to 28 ℃ under general air conditioning over a year, compared to precision air conditioning.
You will find that the difference in change of electric resistance under the precision air conditioning that is controlled within a range of 0.1 ℃ should not be underestimated.
As we see it through a year, the rate of electric resistance is unstable under general air conditioning when compared to precision air conditioning, and the evaluation precision of electrical properties drops significantly.
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