Question 1

What is the LIN-120C and what makes it unique among Com-Power LISNs?

Accepted Answer

The LIN-120C is a dual-conductor, 50Ω, 50 μH Line Impedance Stabilization Network (LISN) that combines both the Line and Neutral single-conductor networks in a single enclosure, rated at 20 amperes AC per line, and uniquely includes an integral Transient Limiter with a 10 dB attenuator and an ON/OFF bypass switch built directly into the unit. Unlike any other Com-Power LISN, the LIN-120C does not require an external Transient Limiter accessory to protect the EMI receiver from voltage transients, attenuate out-of-band emissions, and provide impedance matching between the LISN RF port and the measurement instrument. The combination of dual-conductor convenience, universal EUT receptacle, and integrated transient limiter makes the LIN-120C the most self-contained single-instrument solution in the Com-Power LISN range for commercial conducted emissions testing per CISPR 16-1-2 and ANSI C63.4.

Question 2

What standards does the LIN-120C comply with and what network type does it implement?

Accepted Answer

The LIN-120C is fully compliant with CISPR 16-1-2 and ANSI C63.4. It implements a 50Ω / 50 μH CISPR V-network configuration for CISPR 16-1-2 testing and a 50 μH ANSI network configuration for ANSI C63.4 testing. Both CISPR and ANSI configurations are covered by the individual calibration supplied with the unit. The LIN-120C is accepted by accredited EMC test laboratories worldwide for commercial product conducted emissions compliance testing.

Question 3

What is the frequency range of the LIN-120C and how does it differ from the LI-220C?

Accepted Answer

The LIN-120C covers 150 kHz to 30 MHz, which is the standard commercial conducted emissions frequency range defined by CISPR 16-1-2 and ANSI C63.4 for the 50 μH V-network LISN. The LI-220C covers an extended range of 9 kHz to 30 MHz. The LIN-120C is the appropriate choice when testing is required only over the standard 150 kHz to 30 MHz commercial range and the integrated Transient Limiter is desired. The LI-220C is required when measurements must extend below 150 kHz to 9 kHz, for products such as power line communication devices, smart meters, or EV chargers where sub-150 kHz conducted emissions are relevant, or when the ANSI 250 μH network configuration is required.

Question 4

What is the integral Transient Limiter in the LIN-120C and how does the ON/OFF bypass switch work?

Accepted Answer

The LIN-120C includes a built-in Transient Limiter circuit that protects the RF input of the measuring instrument from potentially damaging instantaneous voltage transients generated by the EUT or the power line. The internal Transient Limiter incorporates two 5 dB attenuation/impedance matching pads providing a combined 10 dB of attenuation, plus low-pass and high-pass filter sections that attenuate out-of-band emissions outside the 150 kHz to 30 MHz measurement range. A front-panel TRANSIENT LIMITER ON/OFF switch controls whether the Transient Limiter circuit is in the RF measurement path. When the switch is ON, the 10 dB attenuation and filter sections are active, providing full receiver protection and out-of-band rejection. When the switch is OFF, the Transient Limiter circuit including all 10 dB of attenuation and the band-pass filters is bypassed, and the LISN RF port is connected directly to the measurement output. The bypass position may be used when the 10 dB of attenuation is not required and direct RF output is needed, though receiver protection is then the operator’s responsibility.

Question 5

What is the current rating of the LIN-120C and what class of products does it support?

Accepted Answer

The LIN-120C is rated at 20 amperes AC RMS per line and 14 amperes DC. This current rating supports the majority of commercial electronic products that plug into a standard AC outlet, including desktop computers and peripherals, monitors and displays, audio and video equipment, network routers and switches, small to mid-size power supplies, LED drivers and lighting fixtures, small motor-driven appliances, medical equipment below Class I risk, and test and measurement equipment. Products drawing up to 20 A at 120 V (2.4 kW) or at 230 V (4.6 kW) can be tested using the LIN-120C.

Question 6

What is the voltage rating of the LIN-120C and what power systems does it support?

Accepted Answer

The LIN-120C is rated at 270 VAC RMS and 380 VDC line to ground. The mains input port is fitted with a standard IEC C20 receptacle, which accepts IEC C19 plugs used with high-current laboratory power distribution cables. The EUT power output port uses a universal multi-configuration receptacle that accommodates AC plugs from most countries without adapters, including North American Type A and B, European Type C, UK Type G, Australian Type I, and others. This universal design eliminates plug adapter logistics when testing products arriving from international manufacturers.

Question 7

How does the dual-conductor design of the LIN-120C work and how is the Line / Neutral selection made?

Accepted Answer

The LIN-120C contains two independent LISN networks within a single chassis: one for the Line (L1) conductor and one for the Neutral (L2) conductor. A front-panel TEST LEAD SELECTION switch connects the RF measurement port to either the Line or Neutral network. The unused network’s RF port is internally terminated at 50 Ω automatically when that network is not selected. The operator switches between Line and Neutral measurements by toggling the front-panel switch without moving any cables. When the integral Transient Limiter is enabled via its ON/OFF switch, both the Line and Neutral measurement paths benefit from transient protection and 10 dB attenuation regardless of which conductor is selected.

Question 8

How does the LIN-120C achieve its defined impedance and why are air-core inductors used?

Accepted Answer

The LIN-120C uses air-core inductors in both the Line and Neutral networks to prevent saturation and permeability variation. Each network contains a 50 μH air-core inductor in series with its power line conductor, combined with capacitor and resistor networks to produce the defined 50 Ω CISPR impedance characteristic at the RF measurement port. Air-core inductors have no ferromagnetic core material that could saturate at elevated current, which would cause inductance to drop unpredictably below 50 μH and invalidate the LISN impedance profile required for compliant measurements. Inductance remains constant at 50 μH regardless of current level up to the 20 A rating.

Question 9

Why is the mounting plate of the LIN-120C left unpainted and what grounding is required?

Accepted Answer

The mounting plate of the LIN-120C is left unpainted to facilitate a low-impedance metal-to-metal connection to the reference ground plane required by CISPR 16-1-2 and ANSI C63.4 test setups. The LISN’s internal capacitors connect power line conductors to the chassis and ground plane, creating leakage current paths that must be properly returned to earth ground for valid measurements and personnel safety. The unpainted mounting plate must be bonded to the reference ground plane before any power connections are made.

Question 10

What RF connector does the LIN-120C use and what is connected to the RF measurement port?

Accepted Answer

The LIN-120C uses a 50 Ω N-type female RF connector at the single RF measurement port. The integral Transient Limiter is in the signal path between the internal LISN networks and this external RF port when the ON/OFF switch is in the ON position. The RF port connects via a 50 Ω coaxial cable directly to the EMI receiver or spectrum analyzer input. When the Transient Limiter is ON, no additional external Transient Limiter accessory is needed between the LIN-120C and the measurement instrument, simplifying the test configuration compared to LISNs that require an external accessory.

Question 11

What insertion loss and isolation does the LIN-120C provide and how does the Transient Limiter affect the measurement path?

Accepted Answer

With the Transient Limiter in the OFF (bypass) position, the LIN-120C provides insertion loss less than 1 dB and isolation greater than 40 dB from 150 kHz to 30 MHz. With the Transient Limiter ON, the 10 dB attenuation of the internal Transient Limiter adds to the LISN insertion loss, for a combined insertion loss of approximately 10.5 to 11 dB. When using the Transient Limiter ON position for compliance measurements, the 10 dB attenuation correction must be accounted for in post-processing: raw EMI receiver readings must be corrected by adding 10 dB plus the LISN insertion loss correction from the individual calibration data to obtain the actual disturbance voltage at the LISN measurement port.

Question 12

How is the LIN-120C individually calibrated and what calibration data is supplied?

Accepted Answer

Every LIN-120C is individually calibrated in compliance with the relevant requirements of CISPR 16-1-2 and ANSI C63.4. Impedance, phase, isolation, and insertion loss data are measured on the specific unit and supplied with it along with a certificate of calibration. ISO 17025 accredited calibration is also available upon request. The calibration covers both the bypass (Transient Limiter OFF) and the active (Transient Limiter ON) configurations so that accurate correction factors are available for both measurement modes.

Question 13

What is the warranty coverage for the LIN-120C?

Accepted Answer

The LIN-120C is covered by a three-year warranty from Com-Power Corporation. The instrument contains no active components in the LISN networks themselves; the Transient Limiter circuit uses passive protection devices. Under normal laboratory operating conditions the LIN-120C has a long service life. Periodic recalibration on a one- or two-year interval is recommended to maintain measurement traceability and confirm that both internal Line and Neutral networks and the integral Transient Limiter continue to meet their published specifications.

Question 14

What are the physical dimensions and weight of the LIN-120C?

Accepted Answer

The LIN-120C measures 6.6 x 14.3 x 13 inches (16.8 x 36.3 x 33 cm) and weighs 10 lbs (4.5 kg). As a single-enclosure dual-conductor unit with a built-in Transient Limiter it requires only one box on the bench, one mains power cable, one EUT connection, and one coaxial cable to the EMI receiver. This minimal footprint and simplified cabling makes it one of the fastest LISNs in the Com-Power range to configure for a standard commercial conducted emissions test.

Question 15

How does the LIN-120C compare to the LI-220C, and how should a laboratory choose between them?

Accepted Answer

Both the LIN-120C and LI-220C are dual-conductor single-enclosure LISNs with universal EUT receptacles rated at 20 A AC. The key differences are: the LIN-120C covers 150 kHz to 30 MHz and has a built-in Transient Limiter with ON/OFF bypass; the LI-220C covers the extended range of 9 kHz to 30 MHz, implements both the CISPR 50 μH and ANSI 50 μH / 250 μH networks, but requires an external Transient Limiter. Choose the LIN-120C when testing is limited to the standard 150 kHz to 30 MHz commercial range and the built-in Transient Limiter simplifies the test configuration. Choose the LI-220C when measurements below 150 kHz or the ANSI 250 μH network configuration are required.

Question 16

How does the LIN-120C compare to the separately housed single-conductor LI-125C and LI-150C pairs?

Accepted Answer

The LIN-120C (20 A, single enclosure, built-in Transient Limiter, universal receptacle) is a more self-contained and faster-to-setup solution than the LI-125C (25 A) or LI-150C (50 A) separately housed pairs. The LI-125C and LI-150C pairs offer higher current ratings, individually calibrated single-conductor units, and Superior Electric SUPERCON shrouded sockets suited for high-current hardwired connections to equipment that does not use a standard AC plug. The LIN-120C is best suited for testing plug-in products where setup speed and compactness are priorities. The LI-125C and LI-150C pairs are better suited for hardwired equipment, higher-current products, or applications where individual network calibration certificates are required.

Question 17

What types of equipment cannot be tested with the LIN-120C and what alternatives should be considered?

Accepted Answer

The LIN-120C is not suitable for equipment exceeding 20 A AC or 14 A DC: use the LI-125C (25 A), LI-150C (50 A), or LI-1100C (100 A) for higher-current products. It is not suitable for products requiring sub-150 kHz conducted emissions measurements: use the LI-220C (9 kHz to 30 MHz). Equipment requiring DO-160 testing should use the LI-325C or LI-350; MIL-STD-461 testing requires the LI-400C or LI-4100; automotive CISPR 25 testing requires the LI-550C. Three-phase equipment may use two LIN-120C units for four conductors or a dedicated LI-3P series LISN.

Question 18

How can the LIN-120C be used in a three-phase power system configuration?

Accepted Answer

As shown in the LIN-120C connection diagram, two LIN-120C units can support a three-phase system: one unit handles Phase A (L1) and Phase B (L2), and the second unit handles Phase C and Neutral. Each unit’s front-panel Test Lead Selection switch independently selects which of its two networks is connected to its RF measurement port. The integral Transient Limiter on each unit provides receiver protection during measurements on all four conductors. For laboratories with a regular need to test three-phase equipment, the LI-3P series purpose-built three-phase LISNs provide a more integrated solution.

Question 19

How is the LIN-120C used in a high-throughput commercial EMC test laboratory testing large volumes of consumer products?

Accepted Answer

In a high-throughput commercial EMC test laboratory that tests dozens of different consumer products per week for FCC and CE marking conducted emissions compliance, the LIN-120C’s self-contained design minimizes setup time per product submission. The universal EUT receptacle accepts any plug without adapter changes between products. The front-panel Line/Neutral selection switch eliminates cable moves between the two conductor measurements. The built-in Transient Limiter means no external accessory needs to be connected, disconnected, or recalibrated separately. A technician can transition from one product to the next by simply unplugging one EUT, plugging in the next, confirming the load condition, and beginning the 150 kHz to 30 MHz scan. This operational efficiency significantly reduces per-product test time compared to setups requiring separate LISN pairs and external Transient Limiters.

Question 20

How does an EMC engineer use the LIN-120C Transient Limiter bypass switch during diagnostic troubleshooting of conducted emissions failures?

Accepted Answer

During conducted emissions troubleshooting, the LIN-120C’s Transient Limiter ON/OFF switch provides diagnostic flexibility. With the Transient Limiter ON, the 10 dB of attenuation protects the receiver and attenuates out-of-band signals for clean in-band measurements, which is the standard operating mode during compliance pre-screening. With the Transient Limiter switched to OFF (bypass), the engineer can observe the full unattenuated RF output including transient content that the Transient Limiter would otherwise suppress. Comparing the spectrum with and without the Transient Limiter in-circuit helps distinguish between true conducted emissions within the 150 kHz to 30 MHz band and out-of-band transient artifacts that are attenuated by the Transient Limiter filters. This comparison is a useful diagnostic step when trying to determine whether a spectral feature seen during initial screening is a genuine in-band conducted emission that requires mitigation or an out-of-band artifact that the Transient Limiter’s filter sections are appropriately rejecting.

Question 21

What is a real-world scenario for using the LIN-120C in an on-site conducted emissions assessment at a manufacturing facility?

Accepted Answer

A contract EMC engineer performing an on-site conducted emissions assessment at a manufacturing facility benefits significantly from the LIN-120C’s compact single-enclosure design and self-contained Transient Limiter. The entire LISN setup requires only the LIN-120C unit, a mains power cable, and a coaxial cable to a portable EMI receiver or spectrum analyzer, with no external Transient Limiter accessory to carry, connect, or potentially leave behind. The engineer bonds the LIN-120C mounting plate to a portable ground reference, plugs the product under assessment into the universal EUT receptacle, connects the RF port directly to the receiver, and begins scanning from 150 kHz to 30 MHz. The integral Transient Limiter protects the portable receiver from the industrial power environment’s transient content, which may be more severe than in a controlled laboratory setting. This portability and self-sufficiency makes the LIN-120C well suited for field assessments, factory acceptance testing, and on-site pre-certification activities.

Question 22

How is the LIN-120C used in DC power system conducted emissions testing?

Accepted Answer

The LIN-120C’s 380 VDC and 14 A DC rating supports conducted emissions testing of DC-powered equipment including 24 VDC and 48 VDC industrial control and telecom equipment, 380 VDC data center power distribution components, and battery-powered devices with onboard DC-DC converters. In the DC configuration, the positive DC supply connects to the Line (L1) input and the negative DC supply connects to the Neutral (L2) input, with earth ground to the chassis terminal. The dual-conductor design handles both positive and negative bus conductors through a single LIN-120C unit, and the integral Transient Limiter with its ON/OFF switch provides the same receiver protection in DC configurations as in AC, important because DC bus switching regulators can generate significant high-frequency transients on the supply rails.

Title	Link
LIN-120C Datasheet	View PDF
LIN-120C Manual	View PDF

LISN 20 Amps for CISPR 16 & ANSI C63.4

LIN-120C

150 kHz to 30 MHz