Wish to see if electronics products are immune to noise

Hello,
We wish to see if our offline Switch Mode LED lights are immune to noise.
Therefore, we will make a special “noise producer” as in the attached. It is simply an LLC converter with one of its switching nodes dragged out of the enclosure for 30 metres. This 30 metres is loosely twisted (it’s also insulated wire). We will drape this 30 metres of “noisy wire” over our products as they are working –to see if it makes them go wrong.
Do you think any of the products will go wrong when the “noisy wire” is draped over them? Might any operating electronics products be disturbed by being brought near to such a wire?
The waveform of the square wave of the wire is also shown. It is a square wave with 7ns rise time.

LTspice simulation of "noise producer" attached also.

By the way, the LLC converter ('noise producer') shown feeds off the output of a fully isolated full bridge converter, which itself feeds off the output of a 240VAC mains PFC stage

I doubt you would prove anything using that method. The most vulnerability will be at frequencies where there is some resonance on your boards and that would typically be in the 10s of MHz range and higher. You might get some idea of vulnerable frequencies by sweeping your boards with a GDO to find likely 'hot' frequencies then try attacking them with an oscillator and wire antenna. Brian.

I doubt you would prove anything using that method.

Click to expand...

No. Devices required to comply with EMC standards will be tested with respective IEC 61000-4-x methods. Particularly 4-4 (Burst) and 4-6 (Conducted disturbances).


Pre-compliance tests during development can use any useful method that stress devices with fast pulses and high frequent stationary signals. But due to lack of comparability, the validity is rather limited.

Thanks, we are still interested in the possibility of a "dragged out" switching node exactly like shown causing other electronics to fail. -Or even making the power supply itself fail (the one thats had its swithcing node dragged out as shown)
Its a long story why...if you wish i can tell you?
This isnt anything to do with official regulatory noise immunity testing.

We will drape this 30 metres of “noisy wire” over our products as they are working –to see if it makes them go wrong.
Do you think any of the products will go wrong when the “noisy wire” is draped over them? Might any operating electronics products be disturbed by being brought near to such a wire?

Click to expand...

The influence the "long wire" will have to other electronic products depends on that "electronic product" you bring nearby.
For example, just before starting you already have other "electronic products" nearby your noise switch node, e.g. the Full Bridge, PFC. It depends on how close they are and how immune to noise your "electronic products" are (low area loops etc..).

LLC's switch node might have little influence on the Full Bridge because the Full Bridge was designed with small loops etc.. so it is less immune to noise. Now, it depends on your other "electronic products".

A way to roughly estimate your circuit "noise immunity" is shown in **broken link removed**.