Direct-reading absolute calibration of ac voltage ratio standards

A new system for ac voltage ratio absolute calibration has been developed at IEN. The voltage ratio is maintained with a new one-decade, two-stage inductive voltage divider. The setup for ratio self-calibration is based on the simplest possible application of the bootstrap method: during the step-up the voltage differences are directly read with a vector voltmeter having an extremely high ac common-mode rejection ratio (CMRR).