In our This vs. That series, we're comparing (and contrasting) two seemingly similar products. A lot of products seem the same at first glance but can greatly affect the outcome of your next application. Today, we're discussing the difference shielded and unshielded tray cables can bring to your next application.
Tray cable has many applications in different industries. Individual users seem to think that tray cable is exactly what they are looking for, but oftentimes more information is needed to determine which tray cable would work best. There are many applications that require different types of tray cable, and each has its own specifications that are needed to extend the life of the cable as much as possible.
Tray Cable Basics
Since the industries that use them are usually in extreme environments, tray cable is built to endure conditions like extreme heat, weathering, moisture, and sunlight. Usually, these are used as cables for power and instrumentation. Copper is the material commonly used in conductors for underground applications because it's a versatile choice for power and signal transmission to keep interference at a minimum. It is usually utilized for the connection in wire ways, furrows, channels, trays, trenches, gutters, conduits, and racks.
Tray cables come with two, three, four, or even five-conductor cables. The two, three, and four-conductor cables are color-coded, while the five-conductor cables are coded using alphanumeric labels. These cables meet bend tests, cold impact examinations, and flame tests, and are certified safe for hazardous applications and resistant to sunlight. Tray cable proves to be very reliable for industrial applications.
The following are the most common categories of tray cable: Power and Control Tray Cables (Type TC), Instrumentation Tray Cables (ITC), Power Limited Tray Cables (PLTC), Fire Alarm Cables, Communication Cable, Optical Fiber Cable, and Wind Turbine Tray Cables (WTTC). Each type has a different set of features that may be advantageous for particular applications.
Shielded vs. Unshielded
There is a difference in cost and effectiveness between shielded and unshielded tray cables; paying for a shield when you don’t need one is a waste of money. However, not getting a shield when you need one will cause many problems. Imagine a ring of vibration or force field that hovers outside of a cable due to the electrical current running through it. That’s called electromagnetic interference (EMI) that could interfere with other cables' EMI or other equipment.
Shielding for tray cables is, generally, longitudinal or helically wrapped polyester tapes backed with aluminum or copper. The protective shield around the cable helps to minimize or eliminate the impact of EMI around drives, motors, instrumentation, and radio equipment. For heavier industrial and utility use, 0.005-inch annealed copper tapes applied helically or corrugated longitudinally are used.
For most power applications, cables can be unshielded, reducing costs. Unshielded tray cables are typically used when they won’t interfere with any other cables or equipment. These cables are flame-retardant and lead-free, so they can be applied safely in a wide variety of uses. Since tray cables are used in locations such as chemical plants, generating stations, and commercial office buildings, their ability to remain safe no matter the surroundings is vital.
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For more information on Tray Cable in general, check out our Tray Cable FAQs page that goes through general features and benefits, the most common insulation and jacket materials, the different types of Tray Cable, hazardous conditions class designations, and standards and guidelines for tray cable ratings.