EMC test pre-compliance for conducted noises on generators

[bagaieb]

Hi, how connect the LISN when the EUT is an AC generator (alternator) ?

Many thanks

 

[bagaieb]

Please, help me !!!!!

 

[bbatecorp]

Teseq has some diagrams on how to set-up your test. You should be able to find them on their website. If you cant send me a message on here or better yet send an email to bberg AT atecorp DOT com and Monday when I get in the office I'll send you them...

 

[bagaieb]

many thanks for your reply bbatecorp, I also sent an e-mail.
I confidently expect some diagrams.

 

[RF_Jim]

Hi, how connect the LISN when the EUT is an AC generator (alternator) ?

Many thanks

bagaieb, since the generator is the DUT (Device Under Test), it is placed as any other DUT on the LISN.

The difference being, the load for the generator (at 50 or 60 Hz) would be placed where the AC Line would normally be placed to power the equipment being tested.

Unless there is some IEC spec or standard that specifies an alternative setup I would think.

The LISN is just to provide a 'path' which splits the noise to a 50 Ohm 'measuring' path and another path for the 50 or 60 Hz line voltage. By providing a split 'path' this way, the LISN also establishes a 'load' for the DUT at RF frequencies at 50 Ohms, after all LISN stands for "Line Impedance Stabilization Network".

The key part being the inductor in the LISN which presents a relatively high impedance to RF frequencies compared to 50 or 60 Hz Line power and with a 50 Ohm connection or tap point the RF should 'see' only the 50 Ohm load (or power 'pad' before the test equipment) which is then routed to a 50 Ohm input of measuring receiver or spectrum analyzer.

One can think of the LISN as a 'bias Tee' for AC Line voltage instead of DC voltage

RF_Jim