Automation Canada - Cables & Connectors Issue - 32

To make it more complicated, the governing body for cable, Underwriters Laboratories (UL) didn't have any standards at
the time for operating voltages between 600 and 1000 V in the US which the new VFD motors were running at. So, as new
products came to market from cable manufacturers, UL responded by developing industry standards for the cables.
The main regulations that govern VFD cable design for 2020 in the US are UL, CSA and National Electric Code (NEC),
Standards under these regulations include:
* UL Standard 1277 - The standard for electrical power and control cables in trays allowing manufacturers with
UL-approved tray cable to market their product as 600 V/1 kV rated. To be dual rated, products must use a recognized
1 kV rated conductor.
* UL Standard 2277 - Similar to 1277 this standard
is for Flexible Motor Supply Cable (Flexible VFD Servo Cable) and Wind Turbine Tray Cable (WTTC) is intended to be
installed in cable trays or raceways within a wind turbine generator and VFD motors with 1000 or 2000 V ratings.
Furthermore, these cables are intended for use
in accordance with the applicable parts of the National Electrical Code (NEC), NFPA 70.
* UL Exposed Run (ER) - Additional crush and impact
test requirements to UL 1277 and 2277. There are three types: TC (tray cables), ITC (instrumentation tray cables), and PLTC
(power-limited tray cables). If these cable types meet certain mechanical requirements, UL permits the manufacturer to add
an " -ER " suffix to the basic listing printed on the cable, i.e. " TC-ER " , " ITC-ER " or " PLTC-ER " . Cables must be secured at
intervals not exceeding 6 feet
(1.8 meters).
* (NEC) NFPA 79 (2018) Chapter 4 - Currently, the general interpretation of the 2018 NFPA for wiring amongst cable
manufacturers is that Chapter 4, Article 4.4.2.8 is intended for inside the panel where the wiring is contained between the
drives and protection equipment (of the panels) that may experience unusual overload and/or a fault condition. The reason
behind this belief is because the requirement is not included in the section that applies to cable for external wiring.
* (NEC) NFPA 79 (2018) Chapter 12 - Conductors, Cables and Flexible Cords, where THHN and TFFN insulation are still
approved.

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Automation Canada - Cables & Connectors Issue

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