RF Injection for Immunity Testing with Near-Field Probes

The near-field probes of the RF Basic Set are now specified for RF injection. For each probe, the maximum power that can be continuously injected over an extended period of time and the probe factor according to IEC 62132-9 are specified.

The new immunity parameters are provided for RF-R 400-1, RF-R 3-2, RF-B 3-2, RF-U 2.5-2, RF-E 02 and RF-E 05. This extends the application of the probes from near-field analysis to targeted RF injection for immunity investigations.

A Guest Article by Dr. Min Zhang: A Practical Example of Troubleshooting

Dr Min Zhang is a UK-based EMC consultant and founder of Mach One Design. He specialises in EMC design, troubleshooting and training. The guest article describes troubleshooting of intermittent HMI screen blackout in a large industrial drive system.

The system under investigation was a three-phase bi-directional power electronics system. Because the screen blackout occurred intermittently, an EMI-related root cause was suspected. The initial assessment indicated that the noise was generated inside the system rather than coupled in from external sources.

Reproducing the Failure Mode

The first step was to reproduce the failure mode before identifying the noise path and implementing countermeasures. A noise source was introduced near the small computer module to replicate the screen blackout observed in the field.

A Langer E1 set with the SGZ 21 burst generator was used. The generator can produce high-level burst pulses with two selectable rise times. The pulse amplitude can be adjusted to control the injected noise level.

Coupling Noise into Circuits and Cables

Several coupling methods were considered, including magnetic and electric field coupling with accessories from the E1 set. A near-field probe was used for the investigation.

A low-impedance loop connected to the 50 Ω input of an oscilloscope showed approximately 6 V peak-to-peak when excited with the BS 02 magnetic field loop probe. This level is sufficient to disturb 3.3 V or 5 V circuits. A high-impedance circuit simulated with a 10:1 passive probe and the 1 MΩ oscilloscope input showed peak-to-peak spikes exceeding 10 V when the ES 02 electric field coupling probe was used.

The failure mode could be triggered when the BS 02 magnetic field probe was positioned at the side of the small computer module.

Identifying Susceptible Cables

To couple noise into the connected cables, the output terminals of the noise generator were effectively shorted so that the generated pulses flowed through a wire. This wire was wrapped around the cables under test, creating strong magnetic coupling between the generator loop and the cables.

This method allowed the cables to be tested individually. The power leads proved to be robust, while the Ethernet cables represented the weakest points. This result was consistent with experience from similar systems.

Emission Mapping in the Cabinet

To understand the noise coupling path, an emissions troubleshooting kit was used. The Langer LF1 set was selected because it is designed for low-frequency noise pickup and offers high sensitivity.

Power electronics systems of this type typically show noise from a few kHz up to tens of MHz. Contactor or relay switching can also introduce transient events. Because the system was a high-voltage system, probing had to be performed at a safe distance.

The LF-R 400 probe was attached to a safety-insulated rescue stick to allow safe probing of the areas of interest. The measurements showed that the area of the small computer module was very noisy. Continuous noise and transient noise during start-up and shut-down were observed.

Proposed Actions

Based on susceptibility testing and emissions mapping, the following actions were proposed:

• Relocate the small computer module to a quieter zone within the cabinet verified by measurement.
• Add a ferrite core, material 31, to the Ethernet cable to improve the noise immunity of the module.

Conclusion of the Troubleshooting Example

By using appropriate test equipment and practical field experience, the relevant noise coupling mechanisms were identified and mitigation measures were implemented to improve system robustness.

The example shows that even intermittent EMI issues can be traced to clear root causes when structured troubleshooting is combined with targeted measurements.

Review: EMV Cologne 2026 in Cologne, Germany

EMV Cologne 2026 was a platform for technical exchange and practical EMC discussions. The focus of the trade fair appearance was direct dialogue with customers, developers and design engineers.

At the live consulting area, real EMC problems were analysed and practical solution approaches were discussed. Demonstrations of development-supporting measurement equipment on devices under test and demo boards showed typical interference phenomena and their influence during the development process.

A particular focus was placed on the new E2 Set TS 23 Immunity Development System. It enables reproducible interference scenarios to be generated in a targeted manner and used for failure analysis and design optimization.

In addition, the extended application option for Langer EMV-Technik near-field probes was presented: RF injection.

The discussions showed the continued demand for early, practice-oriented EMC analyses, including EMC experimental seminars, EMC development-supporting consulting and EMC tools. Langer EMV-Technik thanks all visitors for the open exchange and the technically valuable discussions.