LISN
Encyclopedia
LISN is an abbreviation for 'Line Impedance Stabilization Network'.
A LISN is a device to create a known impedance on power lines of electrical equipment during electromagnetic interference testing. A LISN is typically designed to allow for measurements of the electromagnetic interference
existing on the power line.
It fulfills three main functions:
A LISN is basically a very large and effective "Pi-type" electrical noise filter used in the design and measurement of electronic equipment to meet formal specifications such as the "CE Marking
". Its large capacitors and inductors (which would never be used in consumer equipment for safety reasons involving potentially high-current short-circuit current paths!) absorb nearly all unwanted noise energy and essentially "isolate" electrically the Device Under Test ("DUT") from any of the power mains. The LISN is supposed to keep unwanted conducted noise from coming in on the power mains and tainting measurement of the DUT, and it is also supposed to keep noise generated by the DUT from escaping back into the power mains. The purpose is to allow accurate measurement of noise generated by the DUT using, usually, a broadband spectrum analyzer.
A LISN is a device to create a known impedance on power lines of electrical equipment during electromagnetic interference testing. A LISN is typically designed to allow for measurements of the electromagnetic interference
Electromagnetic interference
Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...
existing on the power line.
It fulfills three main functions:
- It filters the mains voltage and should block higher frequencies than the mains frequency.
- It should provide a characteristic impedance to the device under testDevice under testDevice under test , also known as unit under test , is a term commonly used to refer to a manufactured product undergoing testing.-In semiconductor testing:...
(DUT). - The conducted interference voltage produced by the DUT is transferred to a meter, for example a spectrum analyser or an EMI receiver.
A LISN is basically a very large and effective "Pi-type" electrical noise filter used in the design and measurement of electronic equipment to meet formal specifications such as the "CE Marking
CE mark
CE marking is a mandatory conformity mark for products placed on the market in the European Economic Area . With the CE marking on a product the manufacturer ensures that the product conforms with the essential requirements of the applicable EC directives...
". Its large capacitors and inductors (which would never be used in consumer equipment for safety reasons involving potentially high-current short-circuit current paths!) absorb nearly all unwanted noise energy and essentially "isolate" electrically the Device Under Test ("DUT") from any of the power mains. The LISN is supposed to keep unwanted conducted noise from coming in on the power mains and tainting measurement of the DUT, and it is also supposed to keep noise generated by the DUT from escaping back into the power mains. The purpose is to allow accurate measurement of noise generated by the DUT using, usually, a broadband spectrum analyzer.
Sources
- CISPR 16-1-2
- EN 55016-1-2
- MIL-STD-461E, REQUIREMENTS FOR THE CONTROL OF ELECTROMAGNETIC INTERFERENCE CHARACTERISTICS OF SUBSYSTEMS AND EQUIPMENT, 1999
- VDE 0876-16-1-2 (German)