For environments where reliable connections are crucial, a special type of cable saves the day. Shielded cables are like the electrical cables we know, but with an additional outer layer that is made of conductive material and is connected to earth. Though shielded cables are grounded, they cannot substitute for equipment grounding conductors (EGC) as they cannot handle high fault currents. Read on to understand a shielded cable’s composition, its function, and its applications.
How do shielded cables work?
The purpose of a cable’s shield layer is to protect its internal conductors from electromagnetic interference (EMI). EMIs can be understood as unwanted “noise” coming from signals that distort the transmission within electrical components, circuits, and systems. These distortions result in poor operations, malfunctions, and even failures. A cable is likely to pick up noise when exposed to the electromagnetic fields of nearby devices or natural phenomena. Some common sources of EMI are wireless devices (such as smartphones), radio stations, electric motors, high-voltage power lines, and even fluorescent lights.
In the case of a shielded cable, the shield layer prevents EMIs from disrupting its transmission. In comparison with a cable’s insulation, jacket, or armor, which defends the conductor/s from mechanical and chemical damage, the primary function of a cable’s shield is to protect it from electromagnetic interruptions. There are several types of shielding for cables: braid shields, foil shields, spiral shields, and tape shields.
Shielded cables vs. unshielded cables
The additional shield layer and its specialized design place shielded cables at a higher price point than ordinary unshielded cables. Shielded cables are also typically thicker, more rigid, and less flexible than their unshielded counterparts. As such, working with them requires extra care.
[PHOTO | LABEL: Phelps Dodge High Voltage Cable]
Unlike unshielded cables, shielded cables must be grounded to do their job. Ultimately, a properly installed, high-quality shielded cable can reduce EMIs, minimize technical issues, and offer better network connectivity—unique advantages that cannot be expected from unshielded cables.
Where are shielded cables used?
Though a special kind of cable, shielded cables are far from rare. In fact, they are essential to many key systems and industries that we benefit from in daily life, such as airports, railways, and radio stations. Basically, shielded cables are must-haves in installations where EMIs are likely and it is absolutely necessary to prevent them. Such installations can be found in critical infrastructure where reliable signal transmission is essential. Examples of these applications include:
- Avionics systems, or systems involving aircraft
- Data centers
- Security network systems
- Industrial settings
The settings listed above are considered “noisy” or harsh environments due to the presence of varying electromagnetic fields and electrical noise generated by nearby electrical and electronic equipment. Phelps Dodge’s VFD cable is expertly designed to reduce EMI emissions from variable frequency drives (VFDs) in an expansive range of challenging environments, such as in manufacturing, oil and gas, and even mining. With excellent durability, proven flame retardancy, and superior temperature tolerance, our VFD cable is a dependable choice for all manner of applications, like elevators and escalators, renewable energy systems, and pumping stations. Other shielded solutions in our extensive product line include our space aerial cables, instrumentation cables, medium-voltage cables, and high-voltage cables.
Conclusion
The world of electricity is more fascinating than many might be aware of—with invisible processes at work at all times, requiring the use of specially designed components such as shielded cables to ensure working connections and smooth operations. Phelps Dodge is the Philippines’ leading manufacturer of high-quality wires and cables, with solutions that suit diverse applications. Browse our world-trusted catalog and send us an inquiry to find the right one for your needs!
