By Eileen Harvey
Industrial Ethernet has undeniably become the backbone of Industry 4.0, playing a crucial role in the transformation of traditional manufacturing into smart factories characterized by advanced robotics and high-speed communication. Among the various protocols that facilitate this technological evolution, PROFINET has emerged as a leader. It is particularly valued for its ability to provide real-time data exchange and maintain robust performance under demanding conditions.
One of the more pressing questions that engineers and system integrators often face is whether shielding is always necessary for PROFINET cables, a question that has significant implications for both performance and reliability.
When considering the need for shielding, the answer is nuanced. In many industrial environments, particularly those with high electromagnetic interference (EMI) from machinery, power lines or radio frequency sources, using shielded cables is highly recommended. Shielding protects the integrity of the data transmitted, ensuring that signals remain clear and that communication is reliable. This becomes especially critical in applications involving safety systems or real-time monitoring, where even minor disruptions can lead to significant operational challenges.
What Is Shielding in PROFINET Cables?
Cable shielding is a protective layer—made of foil, braid or both—wrapped around the conductors. Its role is to block electromagnetic interference (EMI) from external sources and prevent data corruption.
Let’s examine three of the most popular types of shielding used in PROFINET cables. Foil shielding (F/UTP) is thin, lightweight and cost-effective, but less durable. Braided shielding (S/UTP) provides strong EMI protection, especially against low-frequency noise. Combination (SF/UTP) uses both foil and braid for maximum shielding. In essence, shielding acts as a barrier between your cable’s data signals and the “noise” of the industrial world.
Sources of EMI in Industrial Environments
Industrial automation settings are hotspots for EMI. Below are some of the common culprits.
Power lines and cables are high-voltage transmission that generates strong electromagnetic fields. Motors and drives that emit electrical noise include AC/DC drives, welding systems and conveyors. Wireless devices include Wi-Fi, Bluetooth and radio-frequency sources. And finally, harsh outdoor environments that can worsen EMI effects encompass UV, moisture and weather.
Without shielding, PROFINET cables risk data loss, downtime or complete system failures.
Shielded vs. Unshielded PROFINET Cables
Shielded PROFINET cables provide protection against electromagnetic interference, ensuring stable data transmission and supporting longer cable runs. They are ideal for harsh industrial environments where electrical noise is common. Typical applications include areas near motors, drives or welding stations, as well as automotive, chemical and food processing plants. These cables are also recommended for outdoor installations where added durability and shielding are essential.
Unshielded PROFINET cables offer a lower-cost alternative that is easier to install, lighter and more flexible than shielded versions. They are best suited for offices, laboratories or clean production areas where EMI is minimal. These cables perform well in low-EMI environments and are appropriate for short cable runs where shielding is not required.
Industry Standards and Requirements
PROFINET follows IEC 61158 and ISO/IEC 11801 Ethernet cabling standards. While unshielded cables are technically allowed, most PROFINET specifications recommend shielding for reliable industrial performance. For mission-critical industries automotive, oil and gas, and pharmaceuticals shielding isn’t just a recommendation, it’s a requirement. These standards serve as the foundation for ensuring reliable and efficient communication over industrial networks.
While it is technically permissible to use unshielded cables in PROFINET applications, most specifications strongly advocate for the use of shielded cabling to enhance performance, particularly in challenging industrial environments. The shielding acts as a barrier against external EMI, which can be prevalent in factories full of machinery, wireless devices and other electronic equipment. By utilizing shielded cables, users can significantly reduce the risk of data loss or corruption, thereby maintaining the integrity of their communication networks.
When Shielding Is Absolutely Necessary
- Proximity to power lines or high-voltage equipment
- Gigabit PROFINET communication (Cat6/Cat7 requirements)
- Cable runs beyond 100 meters with repeaters/switches
- Mission-critical applications like robotics or process automation
When Unshielded Cables May Be Acceptable
- Clean office or laboratory settings.
- Short runs under 20 to 30 meters.
- Controlled test environments.
- Temporary setups with low EMI.
More than 85% of industrial PROFINET installations use shielded cables, highlighting their necessity in real-world environments.
Best Practices for Shielding Effectiveness
To maintain strong shielding performance, PROFINET cables should always be kept at least 20 centimeters away from power cables to reduce interference. Proper grounding is essential, as poor grounding can cancel out the benefits of shielding. Using shielded connectors such as RJ45 plugs with metal shells ensures electrical continuity throughout the connection. It is also important to avoid breaks in the shielding by ensuring proper termination without any gaps. Following bend radius guidelines prevents mechanical stress that can damage the shielding layers and compromise cable performance.
Tips for Choosing the Right Cable
When selecting a PROFINET cable, begin by evaluating the level of EMI in the environment. Factories with motors or heavy machinery require shielded cables for dependable data transmission. For outdoor installations, choose jacket materials such as PUR or UV-resistant PVC to withstand environmental exposure. Balance cost and reliability carefully; although shielded cables may be more expensive, they help prevent costly downtime. To future-proof a network that may scale to Gigabit PROFINET, it is wise to invest in Cat6 or Cat7 shielded cables.
Recommendations
In most industrial environments, shielded cables should be the default choice for optimal protection and stability. Unshielded cables are suitable only in clean and controlled settings where interference is minimal. Always review manufacturer datasheets to confirm compatibility with system requirements, and invest in reputable brands such as L-com and TKD Kabel for consistent performance and proven reliability.
So, do you always need shielding for PROFINET cables?
Not always—but in most industrial automation environments, shielding is critical for reliable communication, uptime and safety. The small cost difference between shielded and unshielded options pales in comparison to the risks of downtime or data errors.
Explore the full range of TKD Kabel through L-com. We’ll fill your orders fast, with same-day shipping on all qualified, in stock, online orders received Monday through Friday before 5 p.m. EST. For TKD-related inquiries, connect with our U.S-based TKD expert Eileen Harvey at eharvey@infiniteelectronics.com.
