Apparatus and method for measuring micro-hm level electric resistance

Abstract

In order to solve the defects of large power volume and low measurement accuracy of the existing micro-ohm-level resistance measuring instrument, the present invention discloses a method for measuring inrush current and a corresponding device. The switch is turned off, so that the controllable power supply in the charging circuit charges an energy storage capacitor, and then the control circuit disconnects the switch of the charging circuit, closes the switch of the discharging circuit, and at the same time sends a trigger signal to the sampling unit, and the discharge of the energy storage capacitor generates a Impulse current to the resistance to be measured; the sampling unit obtains the inrush current and voltage data on the resistance to be measured through the current sensor and voltage sensor in the discharge circuit, and then feeds back to the control unit, which reads these data and obtains the data to be measured through calculation and processing The resistance value of the resistor. The measuring device according to the method of the invention can be widely used in the manufacture of portable high-precision loop resistance testers, switch contact resistance testers, grounding resistance testers and the like.

Description

technical field [0001] The invention relates to a device and method for measuring resistance, in particular to a device and method for measuring micro-ohm level resistance. Background technique [0002] The traditional method of measuring resistance is generally to use DC constant current source measurement, and its measurement principle is very simple: use DC constant current source current to pass through the measured resistance, and perform signal acquisition and A / D (analog-to-digital converter) conversion after signal conditioning , and then calculate and display the output. For the large current loop, since the measured resistance can be as small as micro-ohms, when the output current of the constant current source is relatively small (less than 100A), the voltage drop generated is also very small, and because the signal-to-noise ratio is also small, Therefore, the sensitivity (accuracy) of the resistance measuring device is required to be very high. The traditional ...

AI Technical Summary

Problems solved by technology

[0006] It can be seen from the above formula group that the resistance is a function of the temperature T, and the temperature T is a function of the current I and the time t passing through the resistance, which is a proportional relationship, that is, the longer the current passing time, the higher the temperature rise of the resistance, so that the The resistance value of the measuring resistor changes significantly, seriously affecting the accuracy of the measurement

Images