A Computer-Controlled Calibrator for Instrument Transformer Test Sets

In recent years, test sets for both conventional and analog nonconventional instrument transformers have been made commercially available. Reference transformers are still of the conventional type. Therefore, test sets need to compare an analog signal of a conventional level with another analog signal of a different order of magnitude or, in the case of current-to-voltage transformers, even a different quantity. Traditional designs based on bridge techniques are not suitable for this application. This paper describes a new calibrator that reaches uncertainties of the order of 10 × 10
^-6
while being suitable for the calibration of test sets for nonconventional analog instrument transformers and fully computer-controlled.