Lesson 3/1030%
MODULE 03

How Surge Travels & Standard Waveforms

Surge doesn't care what kind of cable it's riding on -- power, Ethernet, RS-485, or a telephone line all provide a path in. IEC 61000-4-5 captures the resulting real-world transient with two standardized reference waveforms: a 1.2/50 µs open-circuit voltage and an 8/20 µs short-circuit current.

Learning Objectives

🔌
Identify which interfaces surge can travel on
🏠
Trace the chain from lightning to IC failure
📈
Read the 1.2/50 µs and 8/20 µs waveforms
🎛️
Explore how energy scales with waveform parameters

Any conductor entering or leaving an enclosure is a potential surge path. Select an interface to see its typical exposure and coupling mechanism.

IEC 61000-4-5's combination-wave generator produces an open-circuit voltage with a 1.2 µs virtual front time and a 50 µs time to half-value, and (when short-circuited) an 8 µs / 20 µs current -- the classic "1.2/50, 8/20" combination wave. Adjust the parameters below to see how the resulting voltage, current, instantaneous power, and delivered energy change.

Analysis chart comparing an unprotected vs. protected 6kV/3kA surge pulse, showing the 8 microsecond front time, 20 microsecond time to half value, a 6.0kV unprotected peak voltage clamped down to 0.8kV, and 2.7kA of diverted current
A real analysis of a 6kV/3kA combination-wave pulse: notice the labeled front time (Tf) and time to half-value (Th) match the waveform generator below, and how protection clamps the 6.0kV unprotected peak down to 0.8kV while diverting 2.7kA of current.
2000 V
1000 A
1.2 µs
50 µs

The corresponding current waveform keeps the standard's 8/20 ratio, automatically scaling to T1 × 6.67 (front) and T2 × 0.4 (half-value).

KNOWLEDGE CHECK

Module 3 Quiz

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