| 摘要 |
<p>A process and an apparatus for the determination of the total leakage impedance and the maximum conductor contact current of an ungrounded AC power supply system resulting from the total leakage impedance. An AC measurement current is fed into the AC power supply system, which flows through the system leakage impedances and has a continuous dynamic phase-shift with respect to the power supply frequency so that, between supply system and ground, an interference pattern will be formed between the superimposed AC measurement voltage and system voltage component at an interference pattern frequency (difference or beat frequency) of the pattern envelopes which is small with respect to the system frequency. By extracting and processing of the components of the interference pattern, it is possible to determine the AC measurement voltage component contained in the interference pattern. This allows a very precise determination of the total leakage impedance corresponding to the system frequency, and also of the maximum conductor contact current corresponding the total leakage impedance, e.g. by employing a frequency difference of no more than 2 Hertz between the measurement frequency and the system frequency.</p> |
