Shielding is the most efficient way to stop any kind of physical damage against electrical wires. It’s possible to have a 15-ton truck park on it overnight (wouldn’t that be nice). Shielding although it sounds like it may protect from physical abuse, it is quite the opposite. Shielding wire is done for the sake of combating EMI or Electromagnetic Interference, “this is when the radio frequency spectrum, has a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction” (Wikipedia). https://en.wikipedia.org/wiki/Electromagnetic_interference
Sycor Technology Inc. is a well-renowned Multi-Conductor and Multi-Paired distributor. Sycor's Multi-Conductor and Multi-Paired cables are designated for control, communication and computer applications. Shielding enables Multi-Conductor and the Multi-Paired cables to perform without EMI (Electromagnetic interference) affecting it. With multiple forms of shields protecting against magnetic noise, common noise, static noise and most importantly crosstalk, Sycor's able to supply Multi-Conductor or Multi-Paired cables for even the most difficult applications while offering in house cable assembly for any custom requirements.
The classifications of noise that affect Multi-Conductor and Multi-Paired cable performance:
High Noise – Created typically by heavy motors, generators, power lines, induction heating, relay control and electrolytic processes. The high-level noise is commonly in locations like heavy processing plant, mills and steel foundries.
Medium Noise – Wiring near motors and transformer relay control, which are typically used in the average manufacturing plant.
Low Noise – The wiring source is often located from power lines, motors, and control or power relays. This low noise level can often be found in offices, storage areas and in medical or other forms of laboratories.
When it comes to shielding for Multi-Conductor or Multi-Paired cables there are 4 types of standard shielding options, each of which has its own unique attributes that make them a better fit than the others in specific applications:
Braid: The Multi-conductor braid shield has good flexibility and has the material of the shield interwoven into a tubular structure or a rectangular cross-section. The braided Multi-conductor shield is also the oldest form of shielding that is still currently used. These braids come in many different material types like steel, aluminum, copper, tinned copper, silver plated copper & bare copper, while occasionally using fiberglass for the additional strength it offers. The braids only have 55% to 95% coverage. This type of shielding is still used, but the braider (the machine that creates the braid) takes a long period of time and the braid is commonly more expensive than the other alternatives.
- Core size: .012" and larger
- Frequency range: Low to mid frequencies (Up to 100 MHz)
- Flexibility Good
One of Sycor's popular Multi-Conductor Braid Shield products:
Spiral: The Multi-Conductor or Multi-Paired spiral shields often are created out of bare, tinned or silver plated copper strands, while other metals such as steel may be used for additional physical protection. Spiral braids have the highest flexibility and can be easily manufactured with 95% coverage, with less weight than the other shields. The Spiral shields have the wiring material wrapped around a core with 95% to 98% coverage. The spiral shields are effective in applications involving audio frequency and within other audio wiring applications like a microphone or audio applications.
- Core size: .004" - .450”
- Frequency range: Low frequencies (Up to about 1 MHz)
- Flexibility Very Good
Foil: Multi-Conductor and Multi-Paired foil shielding appears in the shape of a foil gum wrapper and is almost always constructed with tape being either Mylar or Aluminum. Being typically constructed with drain wire while still providing 100% shielding, allows for effective higher frequencies. Adding an additional drain wire allows for easy termination and it must be in contact with the metallic part of the shield. With the foil shield, the drain wire must additionally be 1 size smaller than that of the conductor it is terminating. The foil shield is also not recommended for continuous flexing applications, while the termination options are often limited. This specific option is also not strong at withstanding continuous flexing applications.
- Core size: .025" and Larger
- Frequency range: High frequencies (Greater than 100MHz)
- Flexibility Poor
Some of Sycor's popular Multi-Conductor and Multi-Paired Foil Shield products:
- Multi-Paired Individually Foil Shielded Computer Cable
- Multi-Paired Individually Foil Shielded (Low Capacitance) Computer Cable
- Multi-Paired Overall Foil Shielded Computer Cable
- Multi-Paired Overall Foil Shielded (Low Capacitance) Computer Cable
- Multi-Conductor Overall Foil Shield
Combination Shields: Sycor's Multi-Conductor and Multi-Paired cables are created from 2 or more shields that are simultaneously put into a single cable. The most common type of Multi-conductor cable to combine is the braid over foil or braid over braid. The combination shield is typically used for its 100% foil coverage, mechanical strength, its physical protection, the low DC resistance and flexibility. Combination shielding often comes in a tri-shield or quad shield that adds additional protection to the outer braid. The combination shielding also isolates conductors thereby decreasing the chance of EMI and crosstalk between conductors, which increases the Multi-Conductor and Multi-Paired cable performance.
One of Sycor's popular Multi-Conductor combination shielded products:
Additional EMI blocking methods
Being an important part of major telecommunication industries other forms of EMI blockers have been developed and refined. Although these new developments are still not as efficient as shielding, they do offer additional protection where signal reliability is essential. One of the most popular developments in this field is known as “ferrite Beads”. These beads are not a shield, but they do reproduce the effect of shielding and can be used after non-shielded wire has been installed. These beads are placed around each wire and stop any unwanted energy by grounding any electricity.
Shielding is an important part of a cables make up, especially in the communication industry. Each type of shield has pros and cons that work better and worse in different environments. Choosing the right wire can depend on many factors like the type of environment, grounded or ungrounded, amount of flex required and frequency range. Sycor offers all of these shields and has an expert sales team to help guide and answer any questions you may have.
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