Unit-step calibrators for high voltage and high current applications

摘要

Calibration of HV dividers and high currentrnsensors such as shunts, current transformers andrnRogowski coils are often made by comparison withrnreference devices. These reference devices are calibratedrnby higher certified bodies and are assumed stablernover long periods (up to five years). As long asrnstandard voltage or current impulses are compared,rnthis procedure seems to be satisfactory. The traceability,rnhowever, is questionable because there is no referencernto primary standards. The authors describe voltagernand current step calibrators suitable for wide-bandrnapplications with the unit voltage or current levelrntraceable back to adequate DC voltage and currentrnsources. In this way, a secondary standard is providedrnfor frequent performance checks of voltage dividersrnand current sensors in high voltage and high currentrnlaboratories. The unit step calibrators can be verifiedrnperiodically by a higher certified body. Until now,rn10 kV and 1 kA step calibrators have been successfullyrnused. Newer versions with 40 kV and 3 kA arernreadily available.