By Eileen Harvey
Key Takeaways
- Electromagnetic interference (EMI) can disrupt data transmission, create false control signals, cause equipment failures and lead to regulatory noncompliance.
- EMI comes in two forms: radiated EMI travels through the air, while conducted EMI travels through cables and power lines.
- Shielded cables reduce EMI by surrounding the conductors with a conductive layer that blocks external noise and contains internal emissions.
- When choosing a shielded cable, consider conductor size and count, shielding type (foil, braid or combination), flexibility and voltage rating.
- Shielding works best alongside good practice: shielded connectors, proper grounding, separate routing of power and signal cables, and short cable runs.
As electronic devices become more sophisticated and densely packed with components, the challenge of electromagnetic interference (EMI) has escalated significantly. EMI can disrupt the normal operation of electronic systems, leading to performance issues, data corruption and even device failure. Consequently, effective EMI mitigation strategies have become a critical requirement for any engineering project. Among the most effective solutions to combat EMI is the thoughtful selection of shielded cables.
These TKD cables are designed to protect sensitive signals from external interference and to prevent the escape of electromagnetic fields generated by the devices themselves. By understanding the core principles of EMI and the various types of shielding available—such as foil shields, braided shields and overall shielding—engineers can make informed decisions that enhance the performance and reliability of their systems. Let’s start with what EMI is and why it matters.
Understanding EMI and Its Importance
Electromagnetic Interference (EMI) refers to unwanted electrical signals produced by various electrical and electronic equipment. There are two primary types of EMI. Radiated EMI is released into the air from sources like motors, transformers and wireless devices. Conducted EMI travels through conductors such as cables and power lines.
If left unchecked, EMI can cause several issues, including disruption of data transmission in communication systems, generation of false signals in control mechanisms, increased risk of equipment malfunctions or failures, and noncompliance with regulatory standards such as those set by the FCC and CE. To mitigate these risks, shielded cables are commonly utilized in environments where sensitivity to interference is critical. But how exactly does a shield keep that interference out?
How Shielded Cables Reduce EMI
Shielded cables are designed with a protective layer that surrounds the inner conductors. This shield acts as a barrier, either reflecting or grounding external noise while also containing internal emissions. As devices become more sophisticated and densely packed, the susceptibility to EMI—originating from both natural sources and manufactured electronics—has escalated, leading to potential disruptions in communication, data integrity and overall functionality. To combat these challenges, shielded cables have emerged as a pivotal solution in the design and implementation of electronic systems.
These specialized cables incorporate conductive shields that encase the core conductors, effectively absorbing and reflecting electromagnetic radiation. By minimizing the impact of external interference and preventing the escape of signals, shielded cables enhance signal integrity and contribute to compliance with regulatory standards governing electromagnetic emissions. Not every shielded cable suits every application, however, so selection matters.
Choosing the Right Shielded Cable
When selecting a shielded cable for EMI reduction, consider four factors. First is conductor size and count. Applications with multiple signals may require 2, 3, 4, or even 25 conductors. An example of this cable type is TKD Kaweflex 6110 Flexible Power Control Cable – 25 Conductor, 21 AWG , an unshielded option for lower-EMI areas.
A second factor is shielding type. Choose a foil shield for lightweight, high-frequency interference. Opt for a braid shield for durability and low-frequency noise. Choose a combination shield for maximum EMI protection. One example is Kaweflex 6210 Shielded 4-Conductor, 18 AWG.
A third consideration is flexibility requirements. For drag chains and moving machinery, flexible shielded cables are essential. An example of this is Kaweflex 6110 Flexible 3-Conductor, 18 AWG, which is unshielded; the Kaweflex 6210 series offers the same flexibility with shielding. Flexible cables also need the right bend radius to last; see our guide to proper bending radius and flex-life in continuous-motion applications.
A fourth factor is voltage rating and compliance. Look for UL, CSA, VW-1 and FT1 certifications to ensure the voltage rating meets your system needs (600V typical). VW-1 and FT1 are flame tests; learn more about what they mean in our article on cable flammability ratings.
With those factors in mind, here are some cables that fit the bill.
Recommended Shielded Cable Options
Here are three reliable TKD shielded cable options from L-com: Kaweflex 6210 Shielded Flexible Cable, 4 Conductor, 21 AWG, Kaweflex 6210 Shielded Cable, 5 Conductor, 18 AWG and Kaweflex 6210 Shielded Cable, 4 Conductor, 16 AWG.
For unshielded but flexible control options (for low-EMI areas), a good choice is Kaweflex 6110 Flexible 12-Conductor, 16 AWG.
Choosing the right cable is only half the job. How you install it matters just as much.
Practical Tips for Reducing EMI
- Use shielded connectors with shielded cables. Otherwise, EMI can leak at termination points.
- Route power and signal cables separately to avoid cross-interference.
- Maintain proper grounding. Floating shields don’t work.
- Avoid unnecessary cable length. Longer runs increase EMI susceptibility.
- Choose flexible shielded cables for robotics, drag chains and moving equipment. The jacket matters here too; compare options in our guide to cable jacket materials: PVC vs. PUR vs. TPE.
Still have questions? Here are the ones we hear most often.
FAQs (Frequently Asked Questions)
Q1: Do shielded cables eliminate EMI?
A: No, but they greatly reduce EMI and improve system performance. Total elimination often requires multiple strategies (shielding, grounding, filtering).
Q2: Can unshielded cables be used in industrial environments?
A: They can, but it’s risky. In heavy EMI zones (motors, drives, automation), shielded cables are strongly recommended.
Q3: Where can I buy shielded flexible cables?
A: High-quality shielded cables, such as the Kaweflex 6210 series, along with the unshielded Kaweflex 6110 series for low-EMI areas, are available at L-com.
Q4: What is the difference between foil and braided shielding?
A: Foil shielding is a thin layer of aluminum that provides 100% coverage and is most effective against high-frequency interference, while keeping cables lightweight. Braided shielding is a woven mesh of copper wires that offers less than full coverage but greater durability, flexibility and protection against low-frequency noise. Combination shields use both for maximum protection.
Q5: Should a cable shield be grounded at one end or both ends?
A: It depends on the interference. For low-frequency noise, grounding the shield at one end helps avoid ground loops. For high-frequency interference, grounding at both ends is usually more effective. In every case, the shield should be properly terminated, since a floating shield provides little protection.
Conclusion
Electromagnetic interference can cause serious disruptions in today’s technology-driven world. The simplest and most effective defense is selecting the right shielded cable for your application. Whether you need foil, braid or combination shielding, proper cable selection ensures signal integrity, compliance and equipment reliability.
Explore L-com’s range of TKD industrial-grade cables, with same-day shipping on all qualified, in-stock, online orders received Monday through Friday before 5 p.m. EST.