Automatic calibration of precision and programmable AC measuring instruments at IEN

Procedures for the calibration of programmable instruments operating in the field of AC voltage and current have been set up at IEN. They are based on a system for comparison of AC/DC transfer devices and on a system for calibration of programmable instruments that operate under the control of software programs specifically developed. The most recent of these procedures for the calibration of the calibrator of the system and of programmable AC standards are described. Tests of the short and medium term stability of programmable AC standards show the possibility of using such instruments in the new automatic procedures, without a significant degradation of accuracy