Three Phase LISN 1X Series

LI-3P-1X Series – Three-Phase LISN for CISPR 16-1-2 & ANSI C63.4

The Com-Power LI-3P-1X series consists of four models of four-conductor, 50Ω/50 μH Line Impedance Stabilization Networks (LISNs) designed for three-phase conducted emissions testing. Covering current ratings from 16 A to 100 A per line, these LISNs are fully compliant with CISPR 16-1-2 (CE) and ANSI C63.4 (FCC) and support both Delta and Wye power configurations. Each unit features remote line switching via fiber optic interface, a built-in transient limiter, and air-core inductors that prevent saturation.

Model Comparison

How to Choose the Right Model

The four models in the LI-3P-1X series share identical electrical performance characteristics—impedance, isolation, insertion loss, and frequency range—and differ only in their maximum continuous current rating per phase. Selecting the correct model depends on the maximum operating current of the three-phase Equipment Under Test (EUT):

Selection Rule: Always choose a LISN with a current rating that meets or exceeds the maximum continuous per-line current draw of the EUT. Operating a LISN beyond its rated current can cause overheating and damage the internal inductors.

Real-World Applications

Test Setup Overview

Setting up a three-phase conducted emissions measurement with the LI-3P-1X series involves inserting the LISN between the mains power source and the EUT to establish a controlled impedance environment. Below is the typical step-by-step procedure:

1. Place the LISN on the ground reference plane. The unpainted mounting plate must make direct metal-to-metal contact with the conductive ground plane to provide a low-impedance earth connection, which is critical due to high leakage currents.
2. Connect the mains power source to the LISN Power Input port. Use the supplied socket plug connectors to wire the three-phase supply (L1, L2, L3, Neutral, and Protective Earth) to the color-coded input terminals on the rear of the LISN.
3. Connect the EUT to the LISN Power Output port. Use the supplied plug pin connectors to wire the EUT power cable to the output side. The LISN now sits in series between the power source and EUT on all four conductors.
4. Connect the RF measurement port to the EMI receiver or spectrum analyzer. Use a coaxial cable with an N-type connector to link the LISN’s 50Ω measurement port to the 50Ω input of the measuring instrument. The built-in transient limiter provides protection for the receiver’s RF input.
5. Set up the Remote LISN Interface (RLI V2.0). Connect the fiber optic cable between the LISN and the RLI V2.0 unit, and connect the RLI V2.0 to your PC via USB. This enables automated switching between lines L1, L2, L3, and N during the test. Alternatively, use the front-panel membrane buttons for manual line selection.
6. Select the line under test and perform the measurement. When a line is selected, the remaining lines are automatically terminated into 50Ω internally. Measure conducted emissions on each line sequentially across the 150 kHz to 30 MHz frequency range per the applicable test standard.

Tip: In a three-phase Wye configuration, all four conductors (L1, L2, L3, N) are measured. In a Delta configuration without a neutral conductor, only L1, L2, and L3 are measured. Ensure the correct power configuration is documented in the test report.

Key Features Across All LI-3P-1X Models

Included Accessories

Every LI-3P-1X LISN ships with the following items:

Optional Accessories: LIA-COAX-E Coaxial Adapter with Plug Pins for LISN EUT Port • LIA-COAX-M Coaxial Adapter with Plug Sockets for LISN Mains Port