Understanding LISN: Line Impedance Stabilization Network

This page covers LISN, which stands for Line Impedance Stabilization Network. It explains the functions of a LISN used as a Line Impedance Stabilization Network placed between the power line, the EUT (Equipment Under Test), and an EMC analyzer. It also mentions the specifications of LISNs from Keysight Technologies.

Here are the main functions of a Line Impedance Stabilization Network:

• Isolates Power Line Mains from EUT: This ensures clean power is delivered to the EUT. This isolation prevents noise from the power line from coupling to the EMC analyzer, ensuring accurate measurements.

• Isolates Noise from EUT: The LISN prevents noise generated by the EUT from coupling back onto the power line mains. This safeguards other devices connected to the same power line.

• Couples Signal to EMC Analyzer: The signal generated by the EUT is coupled to the EMC analyzer through a High Pass Filter (HPF). The HPF is an integral part of the Line Impedance Stabilization Network.

Specifications of LISN - Line Impedance Stabilization Network from Keysight Technologies

Figure 1 depicts a simplified internal circuit of a LISN. As you can see, it consists of discrete components like capacitors, inductors, and resistors.

Keysight Technologies offers various LISN models, including the 11967C, 11967D, and 11967E. Below are the key features of the 11967E LISN, which operates up to 30MHz:

• Frequency of Power Source: DC to 60Hz
• Maximum Current Capacity: 25 Amp.
• Maximum Voltage: 460V AC line to line and 250 V AC line to GND
• Network L (Inductance): 30 µH to 250 µH
• Network Z (Impedance): 50 OHM