Quick Reference – Immunity Test Steps and Test Time

Here is a quick reference for common EMC immunity tests for a given start frequency, stop frequency, and step size. Outputs are number of steps and time per test.

Test EN IEC 61000-4-6
EN IEC 61000-4-3
Start Frequency 150 kHz 80 MHz 1 GHz 1 GHz
Stop Frequency 80 MHz 1 GHZ 2.7 GHz 6 GHz
Step Size 1% 1% 1% 1%
Number of Steps 633 255 101 182
Time per step 3 3 3 3
Time (seconds) 1899 765 303 546
Time (minutes) 31.7 12.8 5.1 9.1
Time (hours) 0.53 0.21 0.08 0.15

This is just the test time per setup.

For the Conducted RF Immunity test, this should be multiplied by the number of ports under test.

For Radiated RF Immunity, this figure needs to be multiplied by 2 x antenna polarities and 4 x turntable positions, meaning the overall time is 8 times larger.

The outcome here is that to do a full radiated immunity test, from 80 MHz to 6 GHz, takes 3 hours. And that doesn’t account for setup time or investigating failures.

Labview VI For Calculating EMC Immunity Test Frequency Steps and Test Time

This replaces an Excel macro I’ve used in the past with something that can be used in a variety of types test software.

EDIT: now updated to allow addition of specific spot frequencies to the test frequency list

You can download Version 2 here.

TWITL – Shield Prototyping for Sensitive Detectors

This Week In The Lab: prototyping a shielding can for some sensitive detectors.

The customer’s equipment contained some hazardous gas detectors. Despite a good circuit design, one of these sensors wasn’t too happy when tested at industrial 10V/m levels for radiated RF immunity.

EN 50270:2015 imposes some fairly tight limits on the allowed measurement deviation under immunity conditions (depending on the type of gas).

This “fabri-cobbled” shield proved to be a success and a good proof of concept for the customer to take their design forward.

Despite the less than ideal connection made to the PCB ground plane via the screws it was sufficient to achieve a pass.

copper shield for emc emi