The effectiveness of EMC shielding in practice: combining Druseidt silicone cable and Pflitsch EMC cable glands
In industrial applications, EMC problems very rarely result solely from the quality of the cable itself. In practice, the **entire shielding system** is decisive, including both the construction of the cable shield and the method of its termination in the cable gland. A good example of such an approach are the tests performed for the Druseidt shielded silicone cable in combination with the Pflitsch blueglobe EMC gland.
Shield construction: high braid density without mechanical compromises
The standard Druseidt cable used in the tests has a braid coverage of at least 85%, which clearly exceeds many typical industrial cables (often 70–80%). A denser braid means:
- a greater number of contact points with the gland,
- smaller "windows" in the shield,
- better electrical continuity of the shield around the entire circumference.
Importantly, this was achieved without using aluminum foil, which, while improving EMC parameters, significantly increases cable stiffness and impairs its ease of installation. In this case, a small bending radius and high flexibility were maintained, which is of real importance in machinery, robotics, and high-density wiring cabinets.
Shielding attenuation
Shielding attenuation describes the effectiveness of protection against electromagnetic and magnetic fields, especially in higher frequency ranges. It is expressed in decibels (dB).
The following values were obtained in the tests:
- 83.7 dB
- 92.8 dB
- 87.2 dB
For reference:
- 40–60 dB is considered medium-quality shielding,
- 80–100 dB is a very good level, usually found in high-end solutions.
Achieving values close to 90 dB in a system based solely on a braid (without foil) demonstrates the high quality of the cable shield itself and the effective, 360-degree contact of the shield with the EMC gland.
Deviations between samples result from manual laboratory assembly and confirm that installation quality is crucial for the repeatability of EMC parameters.
Transfer impedance
Transfer impedance is one of the most important parameters for evaluating shielding at low frequencies (up to approx. 30 MHz). It describes how much interference penetrates through the shield and is expressed in mΩ/m – the lower the value, the better.
Measurement results:
- 3.3 mΩ/m
- 1.2 mΩ/m
- 2.2 mΩ/m
For comparison:
- typical shielded cables often reach 5–10 mΩ/m,
- values below 2–3 mΩ/m are characteristic of solutions with very high EMC effectiveness.
Achieving a value of 1.2 mΩ/m is particularly significant, as it shows the system's potential when correctly installed and the effective reduction of magnetic coupling.
The role of the EMC gland in the entire system
The results clearly show that the quality of the cable alone is not enough. The Pflitsch blueglobe EMC gland provides:
- uniform, circumferential pressure on the braid,
- stable electrical contact between the shield and the housing,
- minimization of local impedance increases.
It is precisely the combination of the dense cable braid and correct EMC termination that determines the final measurement result.
Practical conclusions
Based on the presented data, it can be concluded that:
- the Druseidt + Pflitsch combination achieves very high EMC effectiveness,
- the cable retains its high flexibility, which is important in dynamic applications, applications exposed to vibrations, or those requiring flexibility during installation,
- low transfer impedance confirms the solution's suitability for applications sensitive to low-frequency interference.
This is an example of a solution where exceptional EMC parameters result from engineering optimization of the entire system and selected components.
