Uncertainty evaluation for a precision phase measurement system at power frequency

A precision phase measurement system was developed based on dual channels digital sampling technology to measure the phase angle precisely at high voltage loss measurement,. The system mainly made up of two digitizes, one programmable switches set, voltage dividers and shunts. Measurement software use to calculate phase and amplitude based on digitizers data. The system could be self calibrated automatic. The phase measurement system needs to reach an excellent measurement perlbrmance at different phase angles, and phase measurement error can be verified at low power factor condition. The paper evaluate the uncertainty for the measurement system for ensure the uncertainty is less than 0.0005 degree at 50 Hz power frequency.