To accurately measure a higher harmonic voltage of a system by using a transformer for capacitor type meter (referred to as PD hereinbelow) and eliminating influences of a secondary load.
After a primary side of a PD 2 is connected to a system 1, a current of an intermediate harmonic of a non-integral multiple of a basic frequency is injected to an injection point in which is a measurement point 9 at the upper stream side than a secondary load 7 of a secondary circuit of the PD before a higher harmonic voltage is measured. An equivalent circuit impedance at the upstream side, at the side of the secondary load of the injection point in is obtained for the intermediate higher harmonic. An equivalent circuit impedance ZPD, ZL at the upstream side, at the side of the secondary load for a higher harmonic to be measured is interpolated with the equivalent circuit impedance and determined. Moreover, an equivalent current source IL parallel to the impedance Z1 is determined. A circuit constant for correcting a frequency characteristic of the PD2 for the higher harmonic to be measured is determined. When the higher harmonic voltage is measured, while influences of the secondary load are eliminated, the higher harmonic voltage to be measured at the primary side is obtained by a measured voltage at a measurement point (a) where the higher harmonic is to be measured and the determined circuit constant. The higher harmonic voltage of the system 1 is thus measured.
TSUKAMOTO MASAKAZU
UNO KATSUHIKO
NATSUDA YASUKAZU
NISSIN ELECTRIC CO LTD