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Frequently Asked Questions from TANO CABLE

Faq
FAQ
Q
What makes one shield better than another?
A
To be most effective the cable shield is tied to a ground—usually a metal amplifier or mixer chassis that is in turn grounded to the AC power line. Cable shielding effectiveness against high-frequency interference fields is accomplished by minimizing the transfer impedance of the shield. At frequencies below 100 kHz, the transfer impedance is equal to the DC resistance—hence, more copper equals better shielding. Above 100 kHz the skin effect previously referred to comes into play and increases the transfer impedance, reducing the shielding effectiveness. Another important parameter to consider is the optical coverage of the shield, which is simply a percentage expressing how complete the coverage of the center conductor by the shield is.
Q
What can tray cable be used for?
A
Tray cable is made for use in petrochemical refineries, industrial control systems, intercom systems, traffic controls relay, power extensions, and for many other high power functions. The cable is recognized for use in Class 1 and 2, Division 2 hazardous locations and for installation in trays, wireways, troughs, ducts, conduit and channels.
Power Limited Tray Cable may be used for burglar alarms, petrochemical refineries, business machines, power limited circuits, intercom systems, cash registers, and industrial control systems.
Q
What types of wire can be installed in Cable Tray systems?
A
Industrial Cable
Industrial Cable from TANO Cable is supplied to a variety of industries. Industrial Cable is used in tough, demanding applications. This type of cable works in high temperature environments as well as high-voltage uses.
It can withstand harsh treatment such as abrasion and contact with flames.
TANO Cable stocks many types of Industrial Cable, including Multi-Conductor Control and Power Cable, Armored Power and Control Cable, and more. These are all available on our website.
Instrumentation Cable
Instrumentation Cables possess excellent electrical, thermal, and physical properties. This type of cable is designed to be able to withstand harsh treatment such as surface abrasion and even contact with flames,
although it can be used in normal conditions as well. The specific types of Instrumentation Cables listed above are made to be used in circuits up to 600 volts.
TANO CABLE also carries another very popular option, 300 Volt Instrumentation Cables, which is suitable for use in lower-voltage applications.
Control Cables
TANO CABLE's selection of high quality Control Cables includes flexible control cables and flexible automation cables. These cables are supplied to a variety of industries and applications, including robotics, manufacturing, construction, power and distribution, and more. They are common in both commercial and industrial markets.
Q
What features does tray cable possess?
A
TANO Cable's tray cable have an abundance of superior features that make them excellent for the aforementioned applications. Our Type TC Tray Cable conforms to specified articles of the National Electrical Code, UL guidelines, and flame tests. The cable is sunlight, heat and moisture resistant.
Q
What's the difference between Type PLTC Tray Cable and Type TC Tray Cable?
A
Type PLTC is Power Limited Tray Cable, rated to only 300 volts, while Type TC is rated to 600 volts.
Q
What are the characteristics of the three basic types of cable shields? Which is best?
A
A braided shield is applied by braiding bunches of copper strands called picks around the insulated, electrostatically shielded center conductor. The braided shield offers a number of advantages. Its coverage can be varied from less than 50% to nearly 97% by changing the angle, the number of picks and the rate at which they are applied. It is very consistent in its coverage, and remains so as the cable is flexed and bent. This can be crucial in shielding the signal from interference caused by radio-frequency sources, which have very short wavelengths that can enter very small “holes” in the shield. This RF-shielding superiority is further enhanced by very low inductance, causing the braid to present a very low transfer impedance to high frequencies. This is very important when the shield is supposed to be conducting interference harmlessly to ground. Drawbacks of the braid shield include restricted flexibility, high manufacturing costs because of the relatively slow speed at which the shield-braiding machinery works, and the laborious “picking and pigtailing” operations required during termination.

     A serve shield, also known as a spiral-wrapped shield, is applied by wrapping a flat layer of copper strands around the center in a single direction (either clockwise or counter-clockwise). The serve shield is very flexible, providing very little restriction to the “bendability” of the cable. Although its tensile strength is much less than that of braid, the serve’s superior flexibility often makes it more reliable in “real-world” instrument applications. Tightly braided shields can be literally shredded by being kinked and pulled, as often happens in performance situations, while a spiral-wrapped serve shield will simply stretch without breaking down. Of course, such treatment opens up gaps in the shield which can allow interference to enter. The inductance of the serve shield is also a liability when RFI is a problem; because it literally is a coil of wire, it has a transfer impendance that rises with frequency and is not as effective in shunting interference to ground as a braid. The serve shield is most effective at frequencies below 100 kHz. From a cost viewpoint, the serve requires less copper, is much faster and hence cheaper to manufacture, and is quicker and easier to terminate than a braided shield. It also
allows a smaller overall cable diameter, as it is only composed of a single layer of very small (typically 36 AWG) strands. these characteristics make copper serve a very common choice for audio cables.

   The foil shield is composed of a thin layer of mylar-backed aluminum foil in contact with a copper drain wire used to terminate it. The foil shield/drain wire combination is very cheap, but it severely limits flexibility and indeed breaks down under repeated flexing. The advantage of the 100% coverage offered by foil is largely compromised by its high transfer impedance (aluminum being a poorer conductor of electricity than copper), especially at low frequencies.
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