EFT / Burst — What It Is & Why It Exists
EFT bursts are the electrical echo of everyday switching — a relay opening, a motor contactor, a breaker. Understand where they come from and why every mains- or cable-connected product must survive them.
An EFT burst is the electrical debris of ordinary switching. When an inductive load — a relay coil, contactor, solenoid, or motor — is interrupted, the collapsing magnetic field drives a fast, high-voltage transient across the opening contacts, which can even arc and re-strike many times in a few milliseconds. The result is a burst of very fast, repetitive spikes coupled onto nearby power and signal wiring.
IEC 61000-4-4 recreates this stress in a repeatable way so products can be qualified against it. Because the spikes are fast (nanosecond edges) and repetitive (thousands per second), they are excellent at finding timing-sensitive upsets — the kind that make a microcontroller reset or a bus glitch.
Any product that connects to mains, long DC cables, or signal/control lines shares an environment with switching loads. A nearby motor starter or a relay on the same panel can inject bursts that reset your MCU, corrupt communications, or trip a safety function — intermittently and hard to reproduce in the field.
This course follows the same practical arc as the rest of the EMC track: understand the stress, learn the standard/setup, trace the coupling, then fix it at the board, cable, and firmware levels — finishing with a bench pre-compliance and debug workflow.
Throughout, we cross-link the Pre-Compliance course for bench technique and the Surge and ESD courses for the protection components that also defend against bursts.