Method and apparatus for calibrating voltage transformer serial addition

Provided are a method and apparatus for calibrating serial addition based on a semi-insulating voltage transformer, comprising a symmetrical high voltage test power supply, a three-port serial voltage transformer, a semi-insulating voltage transformer and an error measuring apparatus. The present invention is characterized by: a complete set of equipment for measuring the traceability of power frequency voltage ratio can be manufactured; calibrating the line according to the serial addition based on the semi-insulating voltage transformer; measuring the relative error between the three-port serial voltage transformer and the semi-insulating voltage transformer; and mathematically processing the measuring result to obtain the voltage coefficient curve of the semi-insulating voltage transformer error. The method is easy to operate without being restricted by voltage level, and can establish, from a low voltage of 10V to a high voltage of 1,000V, a standard power frequency voltage ratio measurement system serving as a measurement standard at the national or provincial/ministerial level.