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计量和维修仪表工作中,在检定镍铬—镍硅热电偶和与该热电偶相应分度号的电子电位差计时,需用该热电偶的温度—绝对毫伏分度表。下面介绍一个经验公式,只须记住该公式所用公式为: E_U=0.04t+∑U_n+10~(-2)ΔtU_(n+1) (1) E_U——相对毫伏值; t——工作端温度; ∑U_n——工作端温度整百度范围内变异毫伏值的代数和; Δt——不满整百度的工作端温度; U_(n+1)——整百度范围内的变异毫伏值。举例说明: 求工作端温度t为763℃时的相对毫伏值。解:先求出∑U_n。因为763℃整百度温度为700℃,所以0℃～700℃之间的整百度之7个变异毫伏值为: ∑U_n=0.10+0.03+0.08+0.19+0.25+0.23 和13个数据,可在没有该分度表的情况下应急使用。计算结果,其误差温度不超过±1℃,毫伏值不超过±0.04mV。十三个数据列表如下:
Metrology and maintenance of instrumentation, the verification of nickel-chromium - nickel-silicon thermocouple and the thermocouple corresponding sub-degree of electronic potential difference meter, the thermocouple temperature-absolute millivolt meter required. Here’s an empirical formula, just remember that the formula used in the formula is: E_U = 0.04t + ΣU_n + 10 ~ (-2) ΔtU_ (n + 1) (1) E_U-- relative millivolt value; t-- work ΣU_n - algebraic sum of the variation of millivolt value over the entire hundredth of working-end temperature; Δt - the working-end temperature of less than the whole hundredths of degree; U_ (n + 1) - variation of millivolt value over the entire hundredth . For example: find the working end temperature t is relative millivolt at 763 ℃. Solution: First find ΣU_n. Because the whole temperature at 763 ℃ is 700 ℃, the seven millivolts of variation over the entire temperature range from 0 ℃ to 700 ℃ are ΣU_n = 0.10 + 0.03 + 0.08 + 0.19 + 0.25 + 0.23 and 13 data In the absence of the index table emergency use. Calculation results, the error temperature does not exceed ± 1 ℃, millivolt value does not exceed ± 0.04mV. Thirteen data lists are as follows: