Low-Frequency One-Step Inductive Voltage Divider with Ratio up to 1: 1000

The advantages and disadvantages of one-step and multidecade inductive voltage dividers at low frequencies, i.e., frequencies below 10 Hz, are discussed. By electronically decreasing the magnetizing current of one-step dividers and by use of a special design, errors become very small. The construction and the calibration of such dividers is described. Preliminary test results of dividers of the autotransformer and the isolating transformer type show in-phase errors of 10-8 (ratio 10-2) and 10-7 (ratio 10-3) of output. Output resistances are in the 10-3 Ω range. The input resistances are about 109 Ω at 81/3 Hz.