The primary differences between the four models are their respective current ratings: LI-3P-116 16 Amps (per line, continuous) LI-3P-132 32 Amps (per line, continuous) LI-3P-163 63 Amps (per line, continuous) LI-3P-1100 100 Amps (per line, continuous) The side panels for each LISN are louvered for cooling purposes.

The LI-3P-163 and LI-3P-1100 also include two internal cooling fans operated by a switch on the rear panel. Three phase LISNs can be operated remotely or locally. Remote switching of the line under test (L1, L2, L3, N) is performed using the RLI-100 Remote LISN Interface, which controls the LISN via fiber optic connection. In addition to the remote method, the line under test can also be selected using the mechanical, four-position switch located on the front panel of the LISNs.

Using either switching method, the lines which are not selected are internally terminated into 50 ohms, while the selected line is terminated by the 50 ohm input impedance of the measuring instrument.