Webinar Question and Answer Results
Q.
How would you specify cable flexibility? Are there certain tests or standards that define this flexibility?
A.
We're not aware of any industry wide tests or standards used to define flexibility. However, Northwire has implemented a sample program, which ensures we understand our customer's definition of flexibility. This helps us determine what our customer's needs and helps us work to design a cable for their application.
Q.
There is armored cabled. Is there a good polymer cable cover, close to armored—as functionally protective as armored?
A.
Cables with the TC-ER (tray cable exposed run) or ITC-/PLTC-ER (instrument tray cable/power-limited tray cable exposed run) listings meet exactly the same crush and impact tests as metal clad cables, but without the metal. For many applications, ER cables are ideal as they keep the cost and size much lower than armored cables. There are additives to cable jackets that will deter rodents if that's a concern. If you need other mechanical protection or cut through protection, there may not be a polymer option. However, there are many armor types, which could be cost-effective options.
Q.
I believe you told me, Northwire does not make armored cable.
A.
Northwire does offer armored cables. We make the cables, outsource the aluminum-interlocked armor and then we put the final jacket on. In addition to aluminum interlock, we provide braid armors, which is completed in-house.
Q.
Where do you find more information on the "green" cable material options?
A.
Material Science Periodicals, Society of Plastics Engineers (SPE), R & D Magazine, PD&D Magazine, IDES and compounding companies are some good sources.
Q.
What percentage of the market is now RoHS compliant?
A.
This is a broad question as the markets and geographic locations are not defined. Our estimation would be between 40 to 50 percent for the world market. China and India have several exemptions that would cause us to estimate this low.
Q.
Do you see all cable going to RoHS?
A.
"All" is a strong term. However, Northwire believes most cable will be RoHS compliant in the next few years. RoHS has created a powerful initiative to reduce potentially hazardous substances within the cable industry. Many of the larger compounding companies that provide materials for wire and cable have eliminated lead from their facilities. And many are working to eliminate the rest of the substances covered in both RoHS and WEEE. The RoHS initiative has exemptions like equipment or large scale stationary tools in fixed industrial plants, monitoring and control instruments and medical devices. However, WEEE will reduce many of those exemptions.
Q.
What jacket materials will not get brittle when in contact with human skin, oils, sweat, etc.?
A.
Certain grades of TPEs, TPUs, PVCs, Polypropylene and Fluoropolymers will maintain their flexibility when in contact with human skin for long periods of time.
Q.
How do you measure shielding coverage?
A.
Shielding coverage is a ratio of area of the conductor that is covered with a shield versus the area not covered.
Q.
What considerations do you need to make to ensure your cable is flexible?
A.
There is flex life and flexibility. Flex life: Special high flex stranding and a design that reduces friction among core components are a few considerations. Flexibility: The stranding type, materials used and jacketing process are key factors in designing a cable that is "flexible" to the touch.
Q.
Do you provide engineering support with regards to the terminations of the cables into connectors (i.e. crimping or soldering recommendations)?
A.
Yes.
Q.
You mentioned using PUR jacketed cable for contractor grade power cords. Is there a UL-listed cable with TPU jacket?
A.
While UL doesn't specifically recognize polyurethane for power cords, there is a category for TPEs. As discussed in the Cable Basics webinar, TPE is a very broad term. Northwire has UL 62 SEOW and SJEOW listings with a TPE jacket that is polyurethane based.
Q.
It seems difficult to find a stock or standard cable to exactly match an application's requirements. What minimum order quantity and lead-time might be expected for a 12- to 15-conductor (1/3 as 12V power) medical device application?
A.
Northwire offers custom designs with no minimums. You can expect shipment in three to four weeks depending on shielding requirements.
Q.
Is PVC use in cables acceptable by the European community? I thought the use of PVC has been prohibited.
A.
PVC cables are still used in Europe and are still manufactured in Europe.
Q.
Can you talk about thermocouple wire braided vs. foil shielding?
A.
The shielding scheme depends on the EMI environment the device will operate in. Foil, braid or a combination of the two could be used.
Q.
What is the typical standard attenuation for your twisted pair? (Magnetic shielding) Your shielded pair? (Capacitive coupled) At what frequency should you ground the shield at both ends?
A.
The attenuation of a twisted pair varies with conductor material, conductor size, dielectric material and frequency. There isn't a standard attenuation. As a rule, radio frequency (RF) is typically the range in which it becomes important that the shield be terminated at both ends of the cable. Another rule is that if the cable exceeds 1/8 the wavelength of the incoming waves.
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