ESD, Burst & Surge — the three immunity tests.

Three transient disturbances, three standards, three very different energies. Those who tell them apart plan protection circuitry and testing more precisely.

Secure your immunity

ESD — electrostatic discharge (IEC/EN 61000-4-2)

Simulates the discharge of static charge (the “spark”). Testing is done via contact discharge (preferred, because reproducible) and air discharge. The standard defines four severity levels: contact typ. ±2 kV to ±8 kV, air ±2 kV to ±15 kV; 4 kV contact / 8 kV air are common. Level 1 = controlled environment, Level 4 = harsh industrial. Testing is stepped up starting from ±2 kV.

Burst / EFT (EN 61000-4-4)

Fast, low-energy, repeated transients such as those produced when switching inductive loads. Single pulse 5/50 ns, in bursts; typical levels 0.5 / 1 / 2 / 4 kV (power lines) or 0.25–2 kV (signal/IO). Coupled in via a capacitive coupling clamp or CDN.

Surge — surge voltage (EN 61000-4-5)

High-energy single surges (lightning, switching operations in the grid). Two waveforms: 1.2/50 µs (open-circuit voltage) and 8/20 µs (short-circuit current). Duration in the µs range — considerably more energy than Burst. Coupled in via a CDN with defined source impedance.

The difference in one sentence

ESD = very short, very high-impedance; Burst = fast & repetitive, little energy; Surge = slow(er) & high-energy. Protection circuitry (TVS, varistors, filters, grounding/shield) must match the respective stress.

Frequently asked questions

Which levels apply to my product?

This is specified by the applicable product or generic standard (industry e.g. EN 61000-6-2; automotive/rail/medical have their own standards). We clarify the framework on a project-specific basis and test throughout development. (Check the standard versions against the valid edition.)

Can you test immunity yourselves?

Yes, throughout development (pre-compliance). The final, accredited test takes place at a notified body — we get your product to the point where it passes there.

Sources: IEC 61000-4-2 (Wikipedia), Texas Instruments – IEC 61000-4-x, IEC 61000-4-2 overview. Levels/waveforms are typical values; the valid edition of the standard prevails.