2) Experiment Noise immunity and lightning surge were tested. Malfunction did not occur in the immunity test. Also, several lightning surge generators (e.g., 10/700 ITU-T and 1.2/50 combination) and coupling/decoupling methods were tested (Figure 2.9-4). It was necessary to test the coupling and decoupling units to confirm the induced waveform and current value, which depended on them (Figure 2.9-5). The results are shown in Figure 2.9-6. L or R Access network C AC mains L or R system Decoupling device Coupling device Surge generator Miti(08)_F2.9-4 Figure 2.9-4 – Example of experimental set-up Observed waveform type 1 Observed waveform type 2 500 400 300 200 100 0 – 100 – 200 – 300 – 400 – 500 40 30 20 10 0 – 10 – 20 – 30 – 40 – 1000 0 1000 2000 – 500 0 1000 2000 Time [ms] Time [ms] Generator Generator Coupled by 9-mF capacitor Coupled by varistor Miti(08)_F2.9-5 Waveform induced to power unit Figure 2.9-5 – Waveform difference by coupling methods Miti(08)_F2.9-6 Figure 2.9-6 – Experimental results – 3 – Case study 2.9