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便携式双电桥(以下简称双电桥或电桥),准确度多为0.2～2.0级,采用整体法检定比较方便。但是,用普通的电阻箱作标准,则会造成大的误差,得出错误的结论,原因主要在于以下两点: 1、因被检双电桥的四端钮C_1、P_1、P_2和C_2分别用引线接在电阻箱的两个端钮上(见图1),致使电阻箱各个十进盘的电刷接触电阻和上述引线电阻都串入测量回路,从而影响了检定结果。 2、按检定规程规定,作标准用的电阻箱准确度级别要求比被检电桥高四倍。但实际使用过程中,一般只用到电阻箱的最后三、四个十进盘,且准确度都是逐级迅速下降的,故普通的电阻箱(如0.01级电阻箱最后几个十进盘都超出了规定)是不能用作为检定双电桥(如2.0级
Portable double bridge (hereinafter referred to as double bridge or bridge), the accuracy of more than 0.2 to 2.0, the overall method of verification more convenient. However, using a normal resistance box as a standard will result in a large error, resulting in a wrong conclusion. The reason mainly lies in the following two points: 1. Because the four-terminal buttons C_1, P_1, P_2 and C_2 of the double bridge under test are respectively Lead wire in the resistor box on both ends of the button (see Figure 1), resulting in the resistance box of each decade disk brush contact resistance and the lead resistance are skewered into the measurement loop, thus affecting the test results. 2, according to test regulations, as the standard resistance box accuracy level requirements than the quarantined bridge four times higher. However, the actual use of the process, the general only use the last three or four resistance box, and the accuracy is rapidly decreased by level, so the ordinary resistance box (such as 0.01 resistance box last ten ten disk Are beyond the provisions) is not used as a test double bridge (such as 2.0 level