Introduction: At present, more than 95% of the high-end precision instruments and meters used in China are purchased from abroad. A large amount of money is used every year to import precision instruments and meters. The implementation of the project will develop metering equipment and equipment products with promising applications to enhance the independent innovation capability of China's scientific instruments and equipment, upgrade the self-equipment level of China's scientific equipment and improve the quality and level of scientific and technological innovation, and effectively support economic and social development and people's livelihood. Improvement is of great significance.

The “National Research Institute of Metrology Sciences Zhang Zhonghua” is responsible for the development of the National Major Scientific Instruments and Equipment Development Project “Wide Limit Ultra High Accuracy Current Measuring Instrument”. The Chinese Institute of Metrology, China National Testing Technology Research Institute, and Yunnan Province Metrology Measurement Technology Research The national major special project jointly submitted by nine institutes including Heilongjiang Institute of Metrology, Measurement and Testing Technology, etc., has now carried out a defense of the topic and is steadily advancing this topic.

At present, more than 95% of the high-end precision instruments and meters used in the country are purchased abroad. A large amount of money is used every year to import precision instrumentation. At the same time, subject to the restrictions of foreign technology blockades, it is difficult for domestic research institutions to buy first-rate equipment abroad, resulting in the level of scientific research being limited to equipment. The special project for the development of national major scientific instruments and equipment is aimed at this unfavorable situation. The "Ultra-wide limit ultra-high-precision current measuring instrument" project mainly uses the "very low load effect distributed sampling resistor" invented by the project team to fundamentally solve the difficulty of precise measurement of a wide range of current limit, using the developed "pole "Low-load-load distributed sampling resistors" is developed with necessary accessories for "wide-range ultra-high-precision current measuring instruments", "self-checking methods for distributed sampling resistor load coefficients" and a series of widely used "high-stability" Constant current power supply, used to replace the corresponding imported equipment.

The main task of the Yunnan Metrology Institute in this project is to use “very low load effect distributed sampling resistors” to improve the stability of constant current source products, develop hundreds or even thousands of amps, and achieve stability levels below 10-5. Constant current source device; improving the accuracy of current measuring instruments; developing a current measuring device with a measurement uncertainty of up to 10-5; developing a conversion accuracy of 80 kA and below for measurement accuracy up to 10-5 Large DC current standard device.

Measurement is an important technological foundation for promoting scientific and technological progress, promoting economic growth and improving people's livelihood. Measuring instruments and meters are one of the major scientific instruments and equipment. The implementation of this project will develop metering equipment and equipment products with promising applications to enhance the independent innovation capability of scientific instruments and equipment in China, improve the self-equipment level of scientific instruments and equipment in China, and improve technological innovation. Quality and level are of great significance in supporting economic and social development and improving people's livelihood.