AUTOMATED CALIBRATION METHODS FOR A HIGH-VOLTAGE PARK DIVIDER

Two new methods of calibrating the 1/10 voltage ratio of a 100-kV Park divider, which has been provided with a set of tenths ratio taps is d escribed. The proposed methods make PC-controlled measurements based o n 1) Wheatstone bridge circuits configurable entirely with the resisti ve sections of the tapped divider, and 2) a digital conductance compar ator, respectively. The 1/10 ratio measurements made by these quite di fferent methods were found to be consistent to 3 ppm of the ratio. The conductance comparison method, with an assessed standard uncertainty of 2 ppm, determined precisely the effect of self-heating on the measu red ratio, minute-by-minute after the rated input was applied. Subdivi ding the established 1/10 ratio to 1/100 and 1/10(5) of input, however , is based on more conventional methods. These subdivided ratios have been given a standard uncertainty not exceeding 6 ppm in the absence o f corona discharge.