LISNs - Single Phase

Single Phase LISNs — Complete Product Range

Com-Power offers a comprehensive range of single phase Line Impedance Stabilization Networks (LISNs) organized into five distinct series, each tailored to specific standards, frequency ranges, and application environments. Whether you are testing consumer electronics to CISPR 16, avionics to DO-160, defense systems to MIL-STD 461, or automotive components to CISPR 25, there is a purpose-built single phase LISN in the lineup. All models feature air-core inductors to eliminate magnetic saturation, 50 Ω N-type RF connectors, individual NIST-traceable calibration, and a three-year warranty.

Single Phase LISN Configuration

Figure 1: Single Phase connection with one set of LISN

The diagram above illustrates the standard single phase LISN test configuration. A pair of individually housed LISN networks is installed in series with the Line (or DC+) and Neutral (or DC−) conductors between the power source and the Equipment Under Test (EUT). Each LISN serves two critical functions: it presents a defined, stable impedance to the EUT across the measurement frequency range, and it isolates the EUT from external noise on the mains supply. This ensures that only the conducted emissions generated by the EUT are measured at the LISN’s RF output port. Both LISN units are grounded to the reference ground plane, which is essential for repeatable, standards-compliant results. This two-network single phase setup is the foundation for all Com-Power single phase LISN series (1x through 5x). For three-phase systems, a second LISN pair can be added in Wye or Delta configuration.

Series-at-a-Glance Comparison

1x Series — Commercial Conducted Emissions (150 kHz–30 MHz)

The 1x Series features single-phase 50 µH air-core LISNs rated from 20 A to 100 A, covering 150 kHz to 30 MHz for CISPR 16 and ANSI C63.4 power line conducted emissions testing. This is Com-Power's broadest lineup with four models—LIN-120C (20 A with built-in transient limiter), LI-125C (25 A), LI-150C (50 A), and LI-1100C (100 A)—covering everything from desktop electronics and LED lighting to industrial motors and heavy-duty inverters. These are the standard-choice LISNs for FCC, CE, and EN compliance testing of commercial and IT products.

2x Series — Extended Low-Frequency Range (9 kHz–30 MHz)

The 2x Series features a single-phase 250 & 50 µH dual air-core LISN rated at 20 A, covering 9 kHz to 30 MHz for CISPR 16 and ANSI C63.4 extended-range power line conducted emissions testing. The LI-220C extends measurements down to 9 kHz—well below the 150 kHz floor of the 1x Series—making it essential for testing LED drivers, switch-mode power supplies, solar inverters, EV chargers, and medical devices where product standards require emissions characterization in the 9–150 kHz band.

3x Series — Military, Aerospace & Automotive (10 kHz–400 MHz)

The 3x Series features single-phase 5 µH air-core LISNs rated from 25 A to 100 A, covering 10 kHz to 400 MHz for DO-160, MIL-STD 461, CISPR 25, and CISPR 16 power line conducted emissions testing. Three models—LI-325C (25 A), LI-350 (50 A), and LI-3100 (100 A)—serve as multi-standard platforms for avionics, defense electronics, radar subsystems, and automotive powertrains. The 5 µH inductor and 400 MHz upper frequency are matched to the LISN definitions in DO-160 Section 21 and MIL-STD 461.

4x Series — MIL-STD 461 CE102 Dedicated (10 kHz–10 MHz)

The 4x Series features single-phase 50 µH air-core LISNs rated at 25 A and 100 A, covering 10 kHz to 10 MHz for MIL-STD 461 CE102 power line conducted emissions testing. The LI-400C (25 A) and LI-4100 (100 A) are purpose-built for the CE102 test method, with multi-frequency AC voltage ratings (50/60 Hz, 400 Hz, 800 Hz) that support military aircraft, shipboard, and vehicle power bus configurations. The LI-4100 also offers optional ISO 17025 accredited calibration.

5x Series — Automotive CISPR 25 (100 kHz–108 MHz)

The 5x Series features a single-phase 5 µH air-core LISN rated at 50 A, covering 100 kHz to 108 MHz for CISPR 25 and CISPR 16-1-2 automotive power line conducted emissions testing. The LI-550C is optimized for vehicle electronics—ECUs, EV powertrain components, ADAS modules, and automotive lighting systems—where conducted emissions must be measured through the FM broadcast band at 108 MHz per CISPR 25 requirements.

Conducted Emissions Test Setup Configurations

Understanding how a LISN fits into your conducted emissions test setup is essential for selecting the right series. The diagrams below illustrate the two primary CE test configurations used across military and aerospace standards, showing the evolution from the current probe method to the LISN-based voltage measurement method.

Setup 1: Current Probe Method (MIL-STD-461C / DO-160)

In the earlier MIL-STD-461C and DO-160 methodology, conducted emissions are measured using a current probe clamped around the power lead. The AC/DC power source feeds through a 10 µF feed-through capacitor (such as the Com-Power CFT-10U) to decouple high-frequency noise from the mains before reaching the current probe. The probe senses conducted current on the wire and delivers the signal to the EMI receiver or spectrum analyzer for measurement. This setup does not use a LISN and relies on the current probe’s transfer impedance for its voltage-to-current conversion.

Setup 2: LISN Method (MIL-STD-461 D/E/F/G)

Starting with MIL-STD-461D and continuing through revisions E, F, and G, the CE102 test method replaced the current probe with a Line Impedance Stabilization Network (LISN). In this configuration, the AC/DC power source connects to the LISN (such as the Com-Power LI-400C or LI-4100 from the 4x Series), which presents a defined, stable 50 µH impedance to the Equipment Under Test. The LISN’s RF output port feeds the EMI receiver or spectrum analyzer directly, providing a voltage-based measurement of conducted emissions on the power lead. A 10 µF feed-through capacitor is placed between the LISN output and the EUT to provide additional high-frequency decoupling. This LISN-based approach delivers more repeatable and accurate results than the current probe method, as the impedance seen by the EUT is precisely controlled and calibrated.

The key difference between the two setups is the measurement point: in Setup 1, the current probe senses emissions after the capacitor; in Setup 2, the LISN both stabilizes the impedance and extracts the measurement signal before the capacitor. This is why MIL-STD-461 D/E/F/G and most modern standards (CISPR 16, CISPR 25, DO-160 latest revisions) mandate the use of a LISN for conducted emissions testing.

How to Choose the Right Series

All Com-Power single phase LISNs include individually calibrated data (impedance, phase, isolation, and insertion loss), NIST-traceable calibration certificates, Superior Electric SUPERCON® shrouded connections for safe and repeatable hookup, and a standard three-year manufacturer warranty. A second LISN pair can extend any model to 3-phase power systems in Wye or Delta configurations.