Improved realization of the unit of power
| Reference number | |
| Coordinator | RISE Research Institutes of Sweden AB - SP Mätteknik, Borås |
| Funding from Vinnova | SEK 600 000 |
| Project duration | January 2017 - December 2018 |
| Status | Completed |
Purpose and goal
The goal of the project was to reduce the Swedish NMIs measurement uncertainty for electrical power at mains frequency to 10 uW/VA and 10 urad or better, which is an improvement by a factor of four compared to our current best measurement uncertainty, to meet the Swedish electricity industry´s needs for calibration. This goal has been achieved and we now have the ability to calibrate the industry´s best reference standards.
Expected results and effects
The improved measurement uncertainty has provided a basis for us to continue to be one of the leading National Metrology Institutes (NMI) in the world in the field of electrical power. It has given us the opportunity to participate in two international key comparisons in the field of power arranged by the International Bureau of Weights and Measures (BIPM). Both the CCEM-K5 for electric power, and the CCEM-K13 for harmonics of voltage and current.
Planned approach and implementation
The measurement uncertainty of the Swedish NMIs Digital Sampling Wattmeter (DSWM) has been improved by reducing the humidity coefficient and long-time drift of the voltage dividers and current shunts used in the DSWM and the verification of the sampling algorithm has been reduced by improved phase locking and sampling with longer aperture time. The measurement uncertainty was also improved by verifying the calibration methodology for the DSWM within a few ppm by direct comparison with the NMIs primary standards for ac voltage and current.