Page 7 - AutomationNOTEBOOK volume 41

FYI continued
is typically used to indicate a fixed or permanent power connections.
Automation Direct sells both Flexible Portable Cord and several types of cable intended for more permanent installations, such
as VFD Cable and Continuous Flexing Motor Supply Cable.
Why use VFD cable?
Variable Frequency Drives (VFDs) generate disruptive elec- trical noise in the environment around them. The noise emitted can affect other devices such as electronic equipment, commer- cial-grade Ethernet systems, and instrumentation wiring. Combined with proper grounding techniques, VFD cables are a key component to combat these problems with high-quality shielding, and insula- tion/cable construction rated for the extreme transient voltages that VFDs can produce.
VFD cable needs to be effectively shielded. Research suggests that shielding systems that include a combination foil & braid types are the most appropriate for VFD applications. Automation Direct VFD cables include:
- 100% coverage aluminum/mylar/
aluminum foil shield - 85% coverage tinned
copper braid shield - Tinned copper drain
wire(s)
What does "Exposed Run" mean?
An "exposed run" of tray cable is any tray cable that extends from a cable tray or raceway to a machine or other electrical device. Exposed runs of standard tray cable more than 6 feet long must be protected with conduit or additional raceway. However, there are special -ER cable
types that can save significant installation costs – as they can extend as far as 50 feet or more from the cable tray if certain conditions are met:
struts, channels or angles, and it must be secured at least once every six feet.
• Type TC-ER cables are required (by NEC) to include an equipment grounding conductor.
• Type ITC-ER cables are limited to an exposed run of 50 feet; PLTC-ER and TC-ER cable have no set length limitations.
These -ER cable types must meet additional crush and impact tests – but the ability to install them without conduit or raceway can offer significant savings: the cable itself is likely to be less expensive than an armored version of the same cable, and the cost and labor to run conduit or extend the cable tray may be eliminated.
AutomationDirect offers Flexible Control Cable with multiple ratings and approvals, including:
• Type TC-ER (eliminates need for conduit/armor)
• Type MTW (meets NFPA 79) • WTTC wind turbine tray
cable
• Class 1 Division 2
hazardous locations
• Direct burial
• Wet and dry location • Oil & sunlight resistant
What is the difference between ‘ exible’ and ‘ exing’ cable?
These terms sound similar, but they have specific meaning in terms of cable selection and
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Editor's Note
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Brain Teasers
• Grounding Configuration
and Termination -
An improper cable
connected to VFDs creates noise-related issues within
the system and improperly terminated cables can
release captured noise
current. AutomationDirect
VFD cables offer both a
ground conductor equal to
the size of the power
conductors as well as
separate drains for the
shielding. •
•
Exposed runs are only allowed in industrial environments which have qualified staff to maintain, supervise, and service the installation.
The cable should be routed along existing machine supports and must be adequately protected by
FYI
• Proper Shielding to Contain Noise -
To avoid noise problems,
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