Voltage measuring device for overcoming thermoelectric potential influence

Abstract

A voltage measuring device that overcomes the influence of thermoelectric potential. Its first stepping disc is composed of a measuring disc and two auxiliary discs that are not welded with resistors. The second stepping disc is composed of a 9×9Ω ring resistance network and two The 1Ω resistor constitutes the measuring disk, ten 0.5Ω resistors form the auxiliary disk, the third stepping disk is composed of a 10×1Ω measuring disk and a replacement disk, each contact of the fourth stepping disk is connected to the third stepping disk The corresponding contacts on the middle measuring board are connected, and three resistances of 80Ω, 720Ω and 7200Ω are connected in parallel with the resistance measuring network in the circuit for range conversion, the minimum resolution is 0.1μV, and the measuring boards are connected by wires without switches. , so that the voltage measurement device can ignore the variation and the influence of thermoelectric potential.

Description

technical field [0001] The invention relates to an instrument for measuring DC voltage. Background technique [0002] At present, for a potentiometer with four measuring discs, the connection between the four measuring discs is generally switched by a switch in the middle disc, which will cause a change in contact resistance and limit the resolution. In order to overcome this problem, a large electric brush is generally used to increase the contact area, and a silver-copper composite material is used; the application number 200510062273.X discloses a new method for solving the deterioration of the switch contact resistance by a potentiometer with four measuring discs. Its first and second stepping discs are composed of a measuring disc and a substituting disc. The resistance values ​​on the measuring disc and the substituting disc are the same. Every time a resistance is added to the measuring disc, the substituting disc reduces the same resistance. The third and fourth ste...

AI Technical Summary

Problems solved by technology

The four measuring discs are connected between the two measuring terminals, so that the brush on the step disc switch is excluded from the measuring circuit, and there is no switching between the resistances on the four measuring discs, so there is no variation; Since the potentiometer step disc switch turns 15 per step 0 24 contacts can be distributed on each layer, the measuring plate and the replacement plate of the first step plate have 21 contacts, two layers are required inside and outside, each layer has resistance, and the inner layer resistance is too poor to bring inconvenience to maintenance , the measuring disc, the replacement disc and the auxiliary disc of the fourth step disc have half layers, and the switch of the step disc also needs two layers inside and outside, and the inner layer also has resistance, which is inconvenient to maintain

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