Line Impedance Stabilization Networks (LISN) – Basics and Overview

Posted by Gianmarco 28/01/2022 0 Comment(s) 7661 Test y Medida,

A line impedance stabilization network (LISN) is a device used in conducted and radiated radio-frequency emission and susceptibility tests, as specified in various EMC/EMI test standards. LISN are also sometimes referred to as artificial networks (AN) or artificial mains networks (AMN).
In conducted emission measurements, LISN are inserted into the supply lines of the equipment under test and provide an RF output to measure conducted emissions.
In many other test set-ups, LISN are inserted into the EUT supply lines just for the purpose of creating a defined source (supply) impedance.
The output impedance of a power supply (source) is hardly ever known and varies from source to source. EMC testing requires a well-defined and repeatable set up, which is created by placing a LISN in series with the source. The equipment under test does no longer see the output impedance of the source, but instead the specified impedance of the LISN.

How does it work?

If you want to measure conducted noise emissions, you could do it as simple as below:

It is definitely possible, to measure conducted emissions produced by the EUT, using this simple set up. However, the amplitude of the conducted emissions will be influenced by the impedance of the source. The source impedance is part of a voltage divider in the overall system and has a significant influence on the amplitude of the measured amplitude of the conducted emissions. As it is necessary to get the same results for the same EUT in any lab, anywhere, it is necessary to remove the impedance of the supply source from the equation.
The picture below shows how a LISN is inserted into the setup, in order to provide a defined impedance for the conducted emissions travelling on the supply lines of an equipment under test:

A LISN can be connected to any power supply and provide the same voltage and current capability as the power supply at the EUT terminals. However, the source impedance of the LISN is specified by EMC standards and enables repeatable conducted emission measurements in any laboratory.

Download the free application note (PDF file)

Model	TBOH01	TBL0550-1	TBL5016-1	TBL50100-1	TBLC08	TBL5016-2	TBL5016-3	TBL5032-3
Impedance	5µH // 50Ω	5µH // 50Ω	50µH // 50Ω	50µH // 50Ω	(50µH+5Ω) // 50Ω	(50µH+5Ω) // 50Ω	(50µH+5Ω) // 50Ω	(50µH+5Ω) // 50Ω
Frequency Range	150 kHz - 108 MHz	150 kHz - 108 MHz	150 kHz - 30 MHz	150 kHz - 30 MHz	9 kHz - 30 MHz	9 kHz - 30 MHz	9 kHz - 30 MHz	9 kHz - 30 MHz
Path	1	1	1	1	2	2	3	3
Maximum Current	10 A	50 A	16 A	100 A	8 A	16 A	16 A	32 A
Maximum Voltage	60V nominal, Component rating: 250V	60V nominal, Component rating: 250V	250V	250V	240V	240V	540V / 260V	540V / 260V
EUT Socket	4mm (banana)	Phoenix High current	Phoenix High current	Phoenix High current	Country specific mains socket	Country specific mains socket	CEE/IEC60309	CEE/IEC60309
Additional Features	-	-	-	-	Filter / Limiter / Attenuator, switchable Artificial hand connection for measuring handheld DUTs PE switchable: 50Ω // 50µH	Filter / Limiter / Attenuator, switchable Artificial hand connection for measuring handheld DUTs PE switchable: 50Ω // 50µH	Artificial hand connection for measuring handheld DUTs PE switchable: 50Ω // 50µH	Artificial hand connection for measuring handheld DUTs PE switchable: 50Ω // 50µH