Absorbing Clamp

1. Basic Understanding of Equipment

1.1 Product Overview

1.1.1 Key Parameters

Parameters	Indicators	Notes
Frequency Range	30 MHz to 1000 MHz	Rated Operating Frequency Band
Output Impedance	50 Ω	Matching Coaxial System
Allowed cable diameter for testing	≤20 mm	Exceeding the specifications may damage the equipment.
Signal Connector	Type N	Output Port
Absorption Clamp Factor CF	-4 dB to 4 dB	That is, the correction factor K varies with frequency
Decoupling Factor (DF)	≥21 dB	Ensure isolation between the test side and the power supply side
Decoupling Factor DR	≥30 dB	Decoupling Capability of Coaxial Cable Shielding
Dimensions	640 mm (L) × 109 mm (W) × 100 mm (H)
Weight	5 kg

1.1.2 Application Scenarios

The AB-CLP Absorbing Clamp (ACA) is a specialized device used for disturbance power testing in the field of electromagnetic compatibility (EMC) and serves as an alternative measurement device for radiated emission testing. By coupling and extracting common-mode disturbance power from the cable under test, it indirectly evaluates the device’s radiated emission levels. Since it does not require a large anechoic chamber, it can significantly reduce testing costs and shorten testing cycles, and is widely used in product R& D debugging and pre-compliance testing scenarios.

1.2 Scope of Application and Basis for Standards

1.2.1 Equipment and Method Standards

The performance of this system’s equipment and the test methods fully comply with the following international and national standards:

Equipment Specifications: CISPR 16-1-3, GB/T 6113.103 (Specifications for Equipment for the Measurement of Radio Disturbance and Immunity—Part 3: Equipment for the Measurement of Disturbance Power)

Test Method Standards: CISPR 16-2-2, GB/T 6113.202 (Methods for Measuring Radio Disturbance and Immunity—Part 2: Measurement of Disturbance Power)

1.2.2 Applicable Products and Test Frequencies

The absorption clamp method is primarily used to evaluate electromagnetic interference radiated by equipment through power and signal lines. The mandatory test frequency bands vary depending on the product standard:

The 30 MHz to 300 MHz frequency range (which provides full coverage when used with the EMI-9KB)
is the mandatory compliance testing range for the vast majority of products. The corresponding product standards include:

CISPR 14-1 / GB 4343.1: Electromagnetic Compatibility—Emission Requirements for Household Appliances, Power Tools, and Similar Equipment; CISPR 15 / GB 17743: Radio Disturbance Characteristics of Electrical Lighting and Similar Equipment.

300 MHz to 1000 MHz (requires use with the EMI-9KC receiver)
The AB-CLP Absorbing Clamp has a rated frequency range of 30 MHz to 1000 MHz, while the EMI-9KC receiver has an upper frequency limit of 1000 MHz.
When testing products such as audio-video receivers and multimedia devices (in accordance with standards such as CISPR 13 and CISPR 32), the standards require evaluation of disturbance power across the entire 30 MHz to 1000 MHz frequency band.

1.3 Equipment Configuration Verification

1.3.1 Unpacking

When unpacking the device, handle it gently to avoid scratching the exterior with sharp tools. After unpacking, first inspect the exterior of the device to ensure there is no visible deformation or dents, and that the buttons are not damaged or loose. If you notice any abnormalities with the device or its accessories, please contact us immediately.

1.3.2 Main Unit and Accessories

See Figure 1-1.

Number	Note
①	AB-CLP Absorbing Clamp
②	Coaxial Cable
③	6 dB Coaxial Attenuator

Figure 1-1

1.3.3 Downloading Electronic Documents

Links to the electronic user manual, warranty card, calibration certificate, and other documents have been sent via email. If you missed the email, please contact us to receive the links again.

2. Safety Precautions

2.1 Electrical Safety

The device under test and the receiver must each be connected to the power grid via an Isolation Transformer that meets the appropriate specifications. Direct connection to the mains power supply is strictly prohibited to prevent power surges and the risk of electric shock.

A separate and reliable grounding system must be installed; the lower the grounding resistance, the more accurate the test results will be. Sharing a grounding electrode with high-power electrical equipment is strictly prohibited, and the grounding terminals of all equipment must be securely connected to the grounding electrode.

Do not use the equipment if the power connections are loose or the cable sheath is damaged; during thunderstorms, disconnect all equipment from the power source and ground connections to prevent damage from lightning strikes.

The receiver’s RF input port is a sensitive RF interface; do not connect high-voltage or high-level signals directly to it, as this may damage the internal circuitry.

2.2 Operational Safety

Strictly follow the sequence: “Turn on the peripherals first, then the computer; turn off the computer first, then the peripherals.”

Before powering on or off the device under test, you must first disconnect the coaxial cable from the front end of the receiver to prevent switching transients from damaging the receiver’s internal circuitry; under no circumstances should you plug in or unplug the coaxial cable during testing.

When opening and closing the Absorbing Clamps, operate them smoothly to avoid pinching your hands; do not insert cables or hard metal objects with a diameter greater than 20 mm into the jaws to prevent the internal ferrite cores from cracking.

During testing, move the absorption clamp by gently pushing and pulling it to avoid violent impacts with the slide rail, thereby preventing displacement of the internal components that could affect test accuracy.

Unless authorized by the manufacturer, do not disassemble the casing of the absorption clamp or the receiver unit; otherwise, your warranty will be void.

2.3 Environmental Safety

The equipment operating environment temperature is 5–35°C, with a relative humidity of ≤80% and no condensation; flammable, explosive, or corrosive materials must not be stored in the test area.

It is recommended that formal testing be conducted in an electromagnetically shielded room; for preliminary testing, select a separate room located far from sources of strong electromagnetic interference—such as variable-frequency drives, arc welders, high-power chargers, and wireless transmitting equipment—to minimize the impact of environmental background noise.

The test area must be at least 0.8 m away from walls and other large conductive objects to prevent electromagnetic wave reflections from affecting the test results.

3. Introduction to Auxiliary Equipment and System Wiring

3.1 EMI-9KB Receiver

3.1.1 Front Panel

See Figure 3-1.

Number	Note
①	Power Switch
②	RF input port, connected to the AB-CLP using a coaxial attenuator and coaxial cable

Figure 3-1

3.1.2 Rear Panel

See Figure 3-2.

Number	Note
①	Power cord jack, connected to an Isolation Transformer
②	Fuse
③	RS-232 communication port: Connect to a computer using an RS-232 cable. If the computer does not have an RS-232 port, you can use the standard RS-232-to-USB adapter cable to connect to the computer. Note: Do not use non-standard cables or adapters, as this may cause communication errors.

Figure 3-2

3.2 Test System Wiring Procedure

Please complete the system wiring in the following order to ensure reliable connections.

Wiring Instructions	Note
① Power Supply Circuit Wiring	Connect Isolation Transformer 1 to the mains power supply; use its output to connect the power supply circuit for the device under test. Connect Isolation Transformer 2 to the mains power supply; connect its output to the EMI-9KB receiver and the computer.
② Wiring the Absorber Clamp to the Receiver	Screw the 6 dB coaxial attenuator onto the N-type output port of the AB-CLP Absorbing Clamp; connect one end of the coaxial cable to the 6 dB attenuator and the other end to the RF input port of the EMI-9KB receiver.
③ Communication Wiring	Use an RS232 cable to connect one end to the RS232 port on the back panel of the receiver and the other end to the computer, either directly or via an RS232-to-USB adapter.
④ Grounding Connection	Reliably connect the receiver’s ground terminal and the metal reference ground plate used for testing to a separate ground electrode using a copper ground wire.

4. EMI-9KB Software Installation and Overview

4.1 Software and Driver Installation

4.1.1 System Operation Requirements

Operating System: Windows 7 / Windows 8 / Windows 10 / Windows 11; Windows 10 is recommended;

Hardware Requirements: Pentium or higher processor, ≥2 GB of RAM, ≥1 GB of free hard drive space, and at least one available USB port;

Screen resolution: 1024×768 or higher is recommended.

4.1.2 Installation

See Figure 4-1.

Number	Note
①	EMI-9KB Receiver PC Software—Double-click to install
②	RS-232-to-USB Adapter Driver: If you are using an RS-232-to-USB adapter, you must install this driver.

Figure 4-1

4.1.3 Communication Port Settings

When you open the software for the first time, you may see a communication error message, as shown in Figure 4-2.

Figure 4-2

Click OK to open the software’s initial interface, then click Test > Port Settings, as shown in Figure 4-3.

Figure 4-3

Simply select the correct communication port number manually, as shown in Figure 4-4.

Figure 4-4

As shown in Figures 4 and 5, you can go to “My Computer” > “Properties” > “Device Manager” to verify the communication port used by the device.

Figures 4–5

The next time you open the software, it will open directly to the initial interface. Note: If the communication port changes, you will need to reselect the correct communication port.

4.2 Introduction to Software Interface Features

4.2.1 File Menu

4.2.1.1 Drop-down List

See Figures 4–6.

Number	Note
①	Open the EMC file
②	Save the test results as an emc file. Note: emc files can only be opened using the LISUN EMI-9KB software.
③	Test Report Settings
④	Print a report that includes data from the final test points
⑤	Print a report that includes data on points of interest
⑥	Exit the Software

Figures 4–6

4.2.1.2 Report Option Information

When saving or printing a test report, the following screen appears first, as shown in Figure 4-7.

Number	Note
①	Save/Print Final Inspection Point/Focus Point Data?
②	Fill in the test-related information
③	Fill in the Laboratory Information

Fig. 4-7

4.2.2 Settings Menu

4.2.2.1 Drop-down List

See Figures 4–8.

Number	Note
①	Test Standards: Select, Add, Edit, or Delete Standards
②	Test parameters: No changes are necessary; simply use the default settings.
③	System Calibration: Used by professional engineers when commissioning the equipment; this function is not required during normal operation.
④	Attenuators: Select based on actual conditions

Figure 4-8

4.2.2.2 Test Standard Options

See Figures 4–9.

Number	Note
①	Selection Criteria: You can only select criteria that have been added previously; you cannot modify their parameters.
②	Add, modify, or delete standards. Note: Please proceed with caution; all standards and limit curves are added according to the standards. If you have other standard data not included in our software, please send us the relevant standards, and we will add them for you.
③	Absorbing Clamps, Voltage Probes, CDN network correction. Note: For use only by LISUN professional engineers when debugging software.

Figure 4-9

4.2.2.3 Attenuator Options

See Figure 4-10.

Number	Note
①	Do not use an attenuator
②	When using an attenuator, please select and enter the correct attenuation parameters in the software.

Figure 4-10

Note: When connecting the EMI-9KB to the AB-CLP, a 6 dB attenuator must also be connected; please set the correct attenuator parameters before use.

4.2.3 Test Menu

See Figure 4-11.

Number	Note
①	For communication port settings, see 4.1.3
②	Scan: Perform a scan test according to the criteria and parameter settings selected at that time.
③	Spot Test: If you only want to view data for a specific frequency point, click here to manually enter the frequency and run the test.
④	Final Test: After the scan test is complete, if you want to test the specific data for certain points again, you can perform a final test.
⑤	Automatic Final Test: The software automatically selects representative frequency points based on the test results for the final test.
⑥	Manual Final Test: Users manually add the frequency points to be tested based on their needs.

Figure 4-11

4.2.4 Display Menu

See Figure 4-12.

Number	Note
①	The graph shows both the default PK and AV lines.
②	Add a monitoring point; this feature works the same as in the final test in version 4.2.3, and you can manually set the frequency points.
③	Display data that falls outside the limit curve
④	Display the data for the final test point
⑤	After performing two consecutive scan tests, you can click to compare the results of the two tests.

Figure 4-12

4.2.5 Introduction to Navigation Bar Shortcut Keys

See Figure 4-13.

Number	Note
①	Open the EMC file
②	Save as an emc file
③	Scan Test
④	Pause Testing
⑤	Stop Testing
⑥	Spot Measurement
⑦	Automated Final Testing
⑧	Manual Final Testing
⑨	Display Curves: PK, AV, PK+AV
⑩	Display data that falls outside the limit curve
⑪	Display data for the final checkpoint
⑫	Show or hide overlapping data points (hiding overlapping data points makes the curve clearer)
⑬	Zoom In/Out: You can zoom in on the curve for easier viewing. After clicking, scroll the middle mouse button wheel in the curve display area to zoom in or out.
⑭	Test Report Settings
⑮	Print a report that includes final test point data
⑯	Print a report that includes data on points of interest
⑰	Exit the Software
⑱	Displays the parameters of the device’s internal modules; intended solely for use by professional engineers during debugging.

Figure 4-13

5. Pre-Test Preparation and System Setup

5.1 Test Environment Requirements

Shielded Room Solution (Compliance Testing): Formal conformity assessment testing must be conducted in a standard-compliant electromagnetic shielded room that completely isolates the test equipment from external interference, ensuring the authority of the test results.

Standard Room Specifications (Preliminary Testing): For R& D preliminary testing, a dedicated room with an area of at least 15 square meters and free of other devices that generate strong electromagnetic interference should be used. Priority should be given to rooms on the first floor to facilitate grounding and reduce grounding resistance.

Sufficient space must be reserved in the test area to accommodate the length of the slide rails and the required spacing between equipment.

5.2 Requirements for Standard Test Setups

The test setup strictly complies with the requirements of the CISPR 16-2-2 / GB/T 6113.202 standard and is divided into two configurations—desktop and floor-standing—based on the type of equipment under test.

5.2.1 Layout of Benchtop Equipment Under Test (EUT)

See Figure 5-1 (taken from CISPR 16-2-2, Figure 8).

Place the insulation test bench above the ground reference plane, with the bench top at a height of 0.8 m; place the equipment under test securely on the test bench, with the rear of the equipment 0.4 m away from the metal wall or ground reference plane.

Place an insulated slide rail that is 0.8 m high horizontally; the rail must be at least 6 m long and located on the same horizontal plane as the equipment under test.

The lead under test (LUT) must be straightened and placed horizontally, with one end connected to the device under test and the other end extending along the slide rail and hanging naturally to the ground, where it is connected to a power source; The total length of the lead under test shall be no less than 7.5 m (including a 6 m section on the slide rail, a 1 m hanging section, and a 0.5 m allowance). If the length of the equipment’s original power cord is insufficient, it must be extended using a replacement cord of the same type and construction.

Open the Absorbing Clamp, insert the wire to be tested into the center hole of the Clamp, close the Clamp, and secure the latch; place the Absorbing Clamp on the slide rail so that it can slide freely along the rail.

The initial distance between the slide rail reference point (SRP) and the clamp reference point (CRP) is set to 10 ± 1 cm. This distance has a significant impact on the test results and must be strictly controlled.

Connect an attenuator, coaxial cable, and the EMI-9KB receiver to the output of the absorption clamp as specified in Chapter 3. Place the receiver on the outer side of the end of the slide rail to avoid interfering with the test area.

Figure 5-1

5.2.2 Floor-Standing Equipment Under Test (EUT) Setup

See Figure 5-2 (taken from CISPR 16-2-2, Figure 9).

Place a metal grounding reference plate measuring at least 2 m × 2 m on the floor. Place an insulating mat 0.1 m high on top of the metal plate, and carefully place the device under test on the insulating mat.

The insulated rail remains at a height of 0.8 m and is positioned horizontally next to the equipment under test; the rest of the wiring layout, absorption clamp installation, and spacing requirements are the same as those for the benchtop unit.

All surfaces of the device under test must be at least 50 cm from the edge of any metal plate and at least 80 cm from any conductive objects in the vicinity.

Figure 5-2

6. Procedure for Interference Power Testing

6.1 Powering On and Warm-Up

First, turn on the Isolation Transformer, then turn on the EMI-9KB receiver, and finally turn on the computer and launch the test software;

After turning on the receiver, let it warm up for 10 minutes; wait until the internal circuitry has stabilized before beginning the test;

Turn on the power to the device under test to bring it into normal operating mode, and allow it to warm up to a stable operating state in accordance with the standard requirements (typically 15 to 30 minutes).

6.2 Confirmation of Test Parameters

6.2.1 Selection of Standards

Refer to Section 4.2.2.2. Go to the standard selection menu and choose the standard labeled “Power”; this is the standard for Absorbing Clamps. See Figure 6-1.

Figure 6-1

6.2.2 Attenuator Settings

Refer to Section 4.2.2.3 and select a 6 dB attenuator, as shown in Figure 6-2.

Figure 6-2

6.4 Scan Test

Click “Scan Test,” wait for the scan to complete, and if any issues arise, click “Stop Test,” make the necessary adjustments, and then restart the test. The scan is complete; see Figure 6-3.

Red line: Quasi-peak (QP) limit line;

Blue line: Average (AV) limit line;

Green curve: Peak (PK) test curve;

Blue curve: Average (AV) test curve.

Figure 6-3

6.5 Final Exam

If the average values (AV) of the test results are all below the limit curve, and the peak values (PK) are all below the quasi-peak (QP) limit curve, then the EUT meets the standard requirements, because the actual quasi-peak (QP) value measured during testing will not exceed the peak (PK) value. If the tested peak value (PK) exceeds the quasi-peak (QP) limit curve, the EUT does not necessarily fail to meet the standard requirements; a final test must be conducted.

6.5.1 Automatic Final Testing

Enter the number of frequency points to be tested, and the software will automatically select frequency points based on the test curve to perform the final test, as shown in Figure 6-4.

Figure 6-4

6.5.2 Manual Final Testing

In the software test curve area, right-click on the point where you want to perform the final test, as shown in Figure 6-5.

Number	Note
①	Add Endpoint
②	Delete Endpoint
③	After adding all the required final test points, click “Start Final Test.”
④	If you no longer wish to participate in the final test, click “Cancel Final Test.”
⑤	The blue diamonds indicate the locations of the added final test points.

Figure 6-5

6.5.3 Adding Points of Interest

See Figure 6-6.

Number	Note
①	Click to clear all frequency points and data from the current screen
②	Tap to edit the frequency point status; tap again to exit the frequency point editing mode.
③	Frequency points for editing; you can manually enter each frequency point
④	You can directly load the frequency point file you edited earlier.
⑤	You can save the frequency point data file you are currently editing so that it can be directly accessed during the final test.
⑥	Click “Create Data” to directly read the test data for the corresponding frequency points from the current test report.
⑦	Read the test data for the corresponding frequency points from the current test report
⑧	Click “Clear Data” to clear the retrieved data.
⑨	Click OK to save the current focus point data to the test report.
⑩	Click EXIT to exit immediately without saving the current screen’s focus point data.

Figure 6-6

6.5.4 Interpretation of Final Test Data

See Figures 6–7. The red X marks the quasi-peak (QP) values from the final test. If all quasi-peak (QP) values from the final test are below the quasi-peak (QP) limit curve, the EUT meets the standard requirements. Otherwise, it does not meet the standard requirements.

Figures 6–7

6.6 Save and Print the Test Report

See Section 4.2.1 to save or print the test report.

6.7 Procedure for Shutting Down the Machine at the End of a Test

Ensure the equipment is in the “test stop” state → Disconnect the coaxial cable on the EMI-9KB receiver side → Turn off the EUT’s power → Turn off the receiver and the computer → Turn off the Isolation Transformer.

7. Daily Maintenance and Care of Equipment

7.1 Routine Maintenance

7.1.1 Absorbing Clamps

After each use, wipe the surface of the pliers with a dry, soft cloth to remove dust and stains; Do not use highly corrosive solvents such as gasoline, acetone, or thinners for cleaning. To remove stubborn stains, use a lint-free cloth dipped in a small amount of anhydrous ethanol to wipe the area quickly, then dry it immediately.

Check the latch and hinge of the pliers monthly to ensure they open and close smoothly; you may apply a small amount of silicone grease for lubrication. Inspect the N-type output connector, remove any oxidation, and cover it with a protective cap when not in use to prevent dust from entering.

Handle the equipment with care; do not drop or subject it to impact, to prevent the internal ferrite cores from shattering. Do not use the pliers to grip hard objects or apply excessive force when opening or closing them.

Do not disassemble the clamp body on your own. The internal magnetic ring and structural alignment have been calibrated before shipment; disassembly will result in a loss of testing accuracy.

7.1.2 Coaxial Cables and Attenuators

Avoid bending coaxial cables sharply, stepping on them, or subjecting them to pressure from heavy objects. When storing them, coil them loosely to prevent the internal conductors from breaking.

Handle precision accessories such as attenuators and connectors with care to prevent internal damage caused by dropping them.

7.2 Storage Specifications

7.2.1 Storage Environment Requirements

Temperature: 5°C to 35°C; relative humidity: ≤65% RH; dry, dust-free environment free of corrosive gases.

7.2.2 Long-Term Storage Operations

Turn off the power and unplug all cables; clean the equipment and wrap it in dust-proof film.

7.3 Calibration Interval Requirements

To ensure the measurement accuracy and operational reliability of the equipment, it is recommended that it be sent periodically to a qualified third-party metrology laboratory for calibration. The recommended calibration interval is 12 months. Users may determine the specific calibration interval based on frequency of use, environmental conditions, and quality system requirements.

8. Troubleshooting and Resolving Common Problems

8.1 Absorbing Clamps

Fault Symptoms	Procedure
The suction forceps do not open and close smoothly, and the latch does not secure tightly	Clean the pivot shaft and apply a small amount of silicone grease for lubrication; remove any foreign objects from inside the jaws and ensure the magnetic ring is undamaged; verify that the diameter of the cable being tested is ≤20 mm, and replace it with a suitable cable.

8.2 EMI-9KB Receiver

Fault Symptoms	Procedure
Various error messages appear while using the software, such as “The software cannot be opened” or “An error occurred during scanning.”	Make sure you’re logged in to your computer with an administrator account, and make sure the software is running with administrator privileges.
The software worked normally during the scan test, but crashed during the final test.	The final test has stricter communication requirements than the scan test. Please ensure that you are using only our original communication cable and no other communication cables or extension cords; please ensure that you are using the communication port on the back of the desktop computer (USB ports on laptops and those on the front of desktop computers typically do not provide sufficient power, which can affect communication); if that still does not work, please try adding an RS232 port to your computer and use only an RS232 cable for communication—do not use an RS232-to-USB adapter.
Test results are generally lower or higher than expected	Please verify that the software attenuator settings match the actual conditions.
Test results are always close to background noise, and the EMI receiver cannot detect any signals.	Check the coaxial cable connection; replace the coaxial cable and try again.
Excessively high background noise and significant fluctuations in test data	Verify that all equipment in the system uses Isolation Transformers; optimize the grounding system to reduce ground resistance; turn off other electrical equipment in the laboratory or conduct testing inside a shielded room.