Why is Shielding Needed in Cable Assemblies?

shielded coaxial cable

Shielded cable assemblies are the right solution required when the environment is doing everything it can to degrade power, signal, and data transfer through an electrical system. In today’s LiveWire cable deep dive, we will explore all the in’s and out’s of shielded cable assemblies, highlighting how these unique support features can absolutely make or break a custom cable assembly. 

What Exactly is a Shielded Cable Assembly?

As a shielded cable manufacturer, our cable engineers have to figure out the exact requirements needed in order to design the perfect shielding plan for the assembly. Too little shielding and the system won’t have adequate protection, too much and you likely have overruns in cost and time. 

So why is shielding so important in cable assemblies? A few key facts to remember:

  • Shielding acts as a buffer for the cables and wires within a cable assembly from disruptive external forces that are constantly bombarding the system. 
  • Cable shielding comes in many different sizes, materials, and manufacturing methods in order to produce the best fit for the project at hand. 
  • One of the most common externalities that requires mitigation in our cable shielding designs is for electromagnetic interference (EMI). 

Shielded cable assemblies are a great way to protect your system from the disruptive effects of EMI. We’ll look at why EMI can be so harmful to the functionality of your electrical system next.

EMI Makes Shielded Cable Connectors Crucial

Whenever a cable harness assembly is sending off data signals, it will need some sort of consideration from any sort of EMI being subjected to the system. EMI comes from an external source and can disrupt the flow of data. EMI can cause ripple effects where the signal is degraded or even fails altogether. EMI is produced by a wide array of processes including both natural and mechanical occurrences. 

In an electrical system with cable assemblies, the source for EMI can be as simple as nearby machines or an electrical circuit. Cable assemblies can wind up in all sorts of situations like industrial control systems in a bottling plant, connecting telecommunications systems in a data center, or providing data transfer in a state-of-the-art medical device. In each of these environments, there can be a variety of electrical “noises” that produce EMI. This EMI requires mitigation to ensure there are no ill effects made to the strength of the data transfer, which could in turn render the greater system inoperable. 

Shielded cable manufacturers know that insulation and jacketing are great for protecting cable assemblies from external forces like heat, moisture, and abrasion, but they do little good for protecting against EMI. That’s where cable shielding produces the greatest benefit.

How Cable Shielding Combats EMI

As we just discussed, the best way for a shielded cable manufacturer to protect against EMI is to utilize shielding in their design. Shielding provides a 360 degree zone of protection around the inner conductors of the cable assembly. Shielding has a number of ways that it protects against EMI, which can be tweaked based on the application. Shielded cable connectors can both reflect and deflect EMI wherever it is most advantageous to dissipate it away from the assembly. 

As you might expect, each and every application is unique. This requires cable engineers to account for a very specific quantity and type of shielding to be utilized. The intended environment, the types of cables, and costs all play into the decision making process for the most efficient design possible. 

Different Types of Shielding Used in Cable Assemblies

Shielded cable assemblies are predominantly found with two different types of shielding, either foil shielding or braided shielding. The type used is going to depend on the needs of the project as both have their strengths and weaknesses. 

  • Using Foil Shielding in Cable Assemblies

Foil shielding is a type that uses thin metal sheets like copper, aluminum, and others, that are attached to different materials such as polyester in order to provide greater resiliency. Foil shields often incorporate a taping that provides great all around coverage for the cables and wires beneath. This provides an effective barrier for the internal system from external EMI. 

  • Braided Shield in Cable Assemblies

The other type of cable shielding you will likely see is braided shielding. Braided shielding incorporates metal weaves of high gauge wires, usually copper. A braid shielding is a good way to create a path that’s low-resistance when grounding and is also able to terminate rather simply, especially when crimped or soldered with a shielded cable connector. 

The only drawback to utilizing braided shields in cable assemblies is that there is never absolute coverage of the system. This can be exactly appropriate depending on the application but do expect to see coverage running below 100 percent down to even 70 percent or more Different metals have different levels of conductivity which makes them great at the job of protecting against EMI. 

Even without total coverage, a braided shield typically performs better than a tape or foil shielding. Braided cords do also incorporate more materials into the project, which means they come at a greater cost and increase scope. Engineering the best use of each type of shielding into our products is what sets apart an experienced shielded cable manufacturer from off-the-shelf products.

Integrating Shielded Cable Assemblies in Your Next Project

Remember our examples above of the bottling plant, medical device, and data center? These locations are particularly “noisy” with respect to EMI because there are so many different electrical systems in the space. Whenever a cable assembly is destined for a location that has an increased level of EMI present, it is almost always ideal to employ multiple layers of cable shielding. Utilizing both a braided shield, as well as a foil shield can offer a particularly stout level of protection. 

When cable assemblies have dozens of different cables and wires carrying out their own functions within the electrical system, sometimes it becomes important to shield even against the EMI produced from adjacent components. Foil shielding can be useful in these instances since it takes up a limited amount of space and envelopes the given shielded connector, wire, cable, or terminal.

Why Shielding Cable Assemblies is So Important

Within a cable assembly, EMI can either be reduced or eliminated altogether depending on the needs of the project. In any application, a sufficient type and amount of shielding is utilized to bring about the best benefit. There are systems which require braided shields, other foil shields, and still other applications requiring a combination of the two. 

Cable assemblies which contain flexed cables may require a different shielding method such as wrapped shielding as opposed to foil shielding which may be prone to spot-failures under such conditions. Above all, grounding is critical with whatever application is occurring. A lot of the shielded cable connectors out there will provide for a termination at the shield. When examining these shielded cable connectors for your own project, remember that each connector needs to provide an adequate level of EMI protection, at least on par with the cable assembly itself. 

These shielded cable connectors can be produced in a variety of materials such as thermoplastics and cast zinc. Whenever the pieces all come together, the different pieces of the assembly, from shielding to termination, have to be properly engineered and calibrated to provide the most efficient overall protection and functionality. 

Certifications Matter With Shielded Cable Manufacturers

Maintaining our ISO 9001 certification requires a commitment towards complete quality of our processes, including manufacturing, logistics, and even customer service. In this way, we continuously strive for improvement. Even if each experience is only marginally better than the last, we are always improving what we produce and how we do so for our clients. The end result is a dependable custom cable assembly that’s going to fit its intended system perfectly.

In addition to maintaining our 9001 certification, we are also extremely proud to be listed as a UL-authorized manufacturing facility. This means that we can help get your products certified by UL and add the coveted mark to your product. The UL symbol on a product is one that’s recognized the world over as a measure of quality, setting your products apart. On a more basic level, utilizing UL parts and products in our own designs lets our engineers use a material with tested and measured characteristics, rather than starting from scratch.

Starting a Project Utilizing Shielded Cable Assemblies

Starting a project on the right foot takes experience, capability, and commitment. After several decades as a leading shielded cable manufacturer in both the U.S. and in China, Meridian cable has developed unique expertise around cable shielding requirements. We incorporate a blend of fully-automated, semi-automated, and hand tools in our manufacturing process and have a tool crib of well over 5,000 different tools at our disposal. 

Finishing projects on-time and on-budget is what we do best. Contact our team today to get started on your own project utilizing shielded cable assemblies.