Inductive loads such as relays, switch contactors, or heavy-duty motors can create high-frequency bursts during transition. The IEC 61000-4-4 test is intended to simulate the transients created by such switching of inductive loads on AC power lines. Figure 8-4 shows the voltage waveforms in to 50Ω termination as defined by the IEC standard.

Figure 8-4 EFT Voltage Waveforms

Internal ESD protection circuits of the THVD24x9 protect the transceivers against ±4kV EFT. With careful system design, one could achieve EFT Criterion A (no data loss when transient noise is present).