Lesson 5/1050%
MODULE 05

Test Setup, CDN & Coupling Methods

A surge test bench looks deceptively simple -- a generator, a box, some cables -- but every component exists to force the surge energy down one specific, repeatable path into the equipment under test.

Learning Objectives

🧰
Identify every component of the surge test bench and its purpose
🔀
Distinguish common-mode from differential-mode coupling
🔌
Recognize line-line, line-ground, line-neutral & neutral-ground configurations

Click each component below to see its purpose, the physics behind it, and the common variants used in real test labs.

Complete IEC 61000-4-5 surge test setup circuit diagram showing the surge test generator with energy storage capacitor and spark gap switch, the coupling and decoupling networks, the EUT (solar inverter), the ground busbar, an HV differential probe, and an oscilloscope capturing the voltage and current waveforms
The complete bench, end to end: the surge generator's internal RLC network and spark-gap switch on the left, the coupling/decoupling network in the middle, the EUT bonded to a ground busbar, and the HV differential probe and oscilloscope capturing the delivered waveform on the right. Every component explored below is one piece of this same chain.

Aspect Common-Mode Differential-Mode
Current path Both conductors to ground/earth, in phase Out and back between two conductors
Typical source Lightning-induced ground potential rise, indirect strikes Switching transients, direct line coupling
Protection component GDT or MOV line-to-ground MOV or TVS line-to-line
Relative real-world frequency More common on outdoor / long cable runs More common indoors, closer to the switching source
KNOWLEDGE CHECK

Module 5 Quiz

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