| 摘要 |
<p>A first impedance of a first electrical device is determined. Additionally, a second impedance, which is either an impedance of the first electrical device or an impedance of a second electrical device, is determined. For each impedance, a test signal at a corresponding main frequency is injected into an electric circuit which is connected with the first and/or the second electrical device. The frequencies of the two test signals are different from each other. After the injection of the two test signals, the voltages and currents representing the response to each test signal are measured and transmitted via analogue transmission channels to a processing device. For the two voltages and two currents only two transmission channels are used. Therefore, a superimposing unit is introduced which superimposes the two voltage measurements and supplies them to one transmission channel and which superimposes the two current measurements and supplies them to the other of the two transmission channels. The processing device then picks out the voltage and current relating to the same frequency and determines the corresponding impedance.</p> |
