An intercomparison of voltage transformer calibration systems was performed between National Center For High Voltage Measurement (NCHVM) and Physikalisch-Technische Bundesanstalt (PTB) in order to confirm their measurement capabilities. Two voltage transformers were used as travelling standards with transformer ratios of 10 kV / 100V and (110kV / √3) / 100V at a frequency of 50 Hz and at ambient temperatures of 23 °C ± 3 °C. The measurements has been performed at test points varying from 20% to 120% of the rated voltage. For the ratio of 10kV / 100V the test results differ by no more than 4 parts in 106 for the voltage ratio and 4 μrad for the phase displacement. For the ratio of (110kV / √ 3) / 100V the results agree within 2 parts in 106 for the voltage ratio and 9 μrad for the phase displacement.