Immunity to fast transients or bursts

The purpose of the test is to verify the ability of the Device Under Test (DUT) to operate correctly in the presence of fast and repetitive transients (bursts) on the power line, signal lines, and load lines. This simulates disturbances generated by switching or disconnecting inductive loads, relay contact bounce, etc.

The test involves using a specific generator that provides a fast transient under open circuit conditions and with a resistive load of 50Ω. The actual output impedance of the generator is 50Ω.

The normalized waveform for the discharge is as indicated in the figure.

Click to enlarge
Click to enlarge

The test voltage ranges from 0.5kV to 4kV, as required by the product standard, and the test is performed with both positive and negative pulse train polarities, for a duration of at least 1 minute for each condition. The disturbance is coupled to the EUT (Equipment Under Test) using a CDN (Coupling Decoupling Network) or capacitive clamp depending on the type of port.

Immunità ai burst o transitori velociThe standard EN 61000-4-4
"Electromagnetic Compatibility (EMC) - Part 4: Testing and Measurement Techniques - Section 4: Immunity to Fast Transients and Bursts" defines the test methodology and the characteristics of the setup and test equipment, including coupling networks or devices. Product technical committees then identify severity levels in terms of voltage level in volts, pulse frequency, and ports to be tested in specific product standards.

During the test, the EUT (Device Under Test) must continue to operate correctly, or according to product standards, temporary performance degradation with autonomous recovery upon disturbance removal is allowed.

Elettra has two burst immunity test setups for single-phase and three-phase devices, with voltage levels up to 4kV and frequencies up to 100kHz.