ESD, burst and surge explained
Three terms that come up constantly in immunity testing. This article explains where the disturbances come from in everyday life, how they differ, and how we investigate them in the shielded chamber in Meine.
Short answer
All three are short-lived disturbance events, but they differ in pulse shape, duration and repetition: ESD is the discharge of a charged person – a single very short pulse with an extremely steep current rise. Burst means packets of very short pulses in rapid repetition, as they arise when switching contacts bounce. Surge means comparatively long, high-energy voltage surges, for instance after a nearby lightning strike – these can destroy components permanently.
The three disturbances at a glance
| Disturbance | Where it comes from in everyday life | Character |
|---|---|---|
| ESD | A person touches the device; friction from clothing or packaging | A single very short pulse with an extremely steep current rise |
| Burst | Bouncing relay contacts, switching of inductive loads | Packets of very short pulses in rapid repetition |
| Surge | A nearby lightning strike, switching of large loads on the mains | A comparatively long, high-energy surge pulse with potential for damage |
ESD: electrostatic discharge
Everyone knows the jolt from touching a door handle. Exactly that event also hits your product – while being operated, while a connector is plugged in, while being unpacked.
For the electronics, the extreme steepness is the problem: the current rises so fast that the discharge spreads over parasitic paths and couples into signal lines instead of draining away cleanly. Typical consequences are resets, display faults, dropped communication and, in the worst case, a destroyed input.
In practice it is less the protection circuitry alone that decides than the discharge path: does the design route the energy through the enclosure, or across the board?
Burst: fast pulse trains
When a relay contact opens or closes, it bounces. What arises is not a single disturbance but a whole train of steep pulses that spreads through the system along the cables.
For the device under test, the repetition is what makes it critical: a single pulse is often absorbed, while a packet in rapid succession upsets state machines and communication links. The typical observation is a device that drops out whenever a machine next door switches.
Burst disturbances travel into the device along cables. Filtering at the input, cable routing and grounding are therefore the usual starting points.
Surge: high-energy voltage surges
Surge is the most energetic of the three disturbances. It is triggered by nearby lightning strikes or by the switching of large loads on the supply network.
Unlike ESD and burst, this is rarely about temporary malfunctions but about permanent damage: shorted semiconductors, destroyed power supplies, damaged interfaces. Surge is therefore also the disturbance where a device may end up broken – we plan that in together beforehand.
The usual starting points are a multi-stage protection concept of coarse and fine protection, plus a series impedance in the affected paths.
How we investigate this in Meine
In the shielded chamber in Meine we couple the disturbances in deliberately and observe how your device reacts: which function drops out, which assembly reacts, at what level the effect appears. Every anomaly is logged with the disturbance, the level, the coupling point and the operating state.
The difference from a formal test lies in the purpose: we want to understand why the device reacts. That is why changes to the setup – filters, shield bonding, cable routing – can be tried out directly and re-measured one at a time.
Which disturbances and which levels make sense, we agree per project in advance. Details of the environment are described under immunity testing and the Meine site.
Have your immunity investigated
Describe the device, its operating states and the anomaly you are seeing – we will agree the test scope with you.