Unit-step calibrators for high voltage and high current applications

摘要

Calibration of HV dividers and high current sensors such as shunts, current transformers and Rogowski coils are often made by comparison with reference devices. These reference devices are calibrated by higher certified bodies and are assumed stable over long periods (up to five years). As long as standard voltage or current impulses are compared, this procedure seems to be satisfactory. The traceabil-ity, however, is questionable because there is no reference to primary standards. The authors describe voltage and current step calibrators suitable for wide-band applications with the unit voltage or current level traceable back to adequate DC voltage and current sources. In this way, a secondary standard is provided for frequent performance checks of voltage dividers and current sensors in high voltage and high current laboratories. The unit step calibrators can be verified periodically by a higher certified body. Until now, 10kV and 1 kA step calibrators have been successfully used. Newer versions with 40 kV and 3 kA are readily available.