01 Development and Performance Evaluation of the NIS-Watt Balance Prototype

This paper presents the progress in developing and testing the operational performance of the NIS-Watt balance prototype, a significant step toward achieving precision mass measurements at the gram level. Designed by the National Institute of Standards (NIS), Egypt, the prototype is based on a modified equal-arm balance and is capable of measuring masses up to 10 grams with a relative uncertainty of 0.01%. The NIS-Watt balance operates on the principle of electromechanical equivalence, integrating velocity and force modes to determine mass based on electrical and mechanical quantities traceable to fundamental constants. Preliminary tests with standard masses of 1 g, 5 g, and 10 g demonstrated the system's reliability and functionality. The results emphasize the potential of the NIS-Watt balance to provide traceable mass measurements, contributing to the broader goal of redefining the kilogram based on the Planck constant. Notably, the calculated Planck constant (ℎ = 6.625427×10−34 J.s) exhibited a relative variation of 95 ppm from the new fixed value. This work marks an essential milestone in advancing precision metrology within the region and contributes to the global metrological community.