EMC Question of the Week: February 5, 2018

Line Impedance Stabilization Networks
Photo credit: Fischer Custom Communications

A Line Impedance Stabilization Network (LISN) is necessary when measuring,

  1. conducted emissions
  2. radiated emissions
  3. electrostatic discharge immunity
  4. all of the above

Answer

The correct answer is "a". International standards for measuring conducted emissions require a Line Impedance Stabilization Network (LISN) to filter out noise coming from the power source and provide a stable impedance to measure noise voltages on the power or communication lines of the equipment under test (EUT).

Although some test labs will power the EUT through an LISN while conducting other EMC tests, it is not required. LISNs do not provide a well-defined impedance to the currents associated with radiated emissions and electrostatic discharge testing.  

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