8Shipboard VFD Cable Selection, Installation, and Termination

IEEE recommendations for shipboard electrical cable construction, application and installation are in IEEE‐45, IEEE‐1580, and IEEE‐45.8.

US Navy cable construction and performance specifications are in MIL Specifications, such as MIL‐C‐24643, MIL‐C‐24640, MIL‐C‐915 as applicable.

For IEC cable requirements are in IEC standards such as 60092‐350 series.

8.1 Shipboard Cable for VFD Application

The adjustable speed drive (ASD) VFD cable should be able to withstand the operating conditions like repetitive 1,600 volt peak voltage spikes from low voltage (450 V) IGBT drives and at the same time not deteriorating the performance of other drive system components.

Peak voltages on a 460 V system can reach 1200 V to 1600 V, which may cause cable insulation failure, and rapid breakdown of motor insulation.

Refer to NEC‐2012 110.27, IEEE‐1580, and IEEE‐45.8.

The new wording proposed is: ‘‘Cable installation should be designed to limit the shield voltage to less than 50 VAC at the maximum ampacity for the specific installation. If the voltage is greater than or equal to 50 VAC, then exposed shields shall be considered as live parts (in accordance with NEC‐2012 110.27) and will require guarding or insulating for personnel protection and the cable manufacturer shall be consulted to determine the suitability of the cable construction to sustain excessive shield voltages.”

8.2 Cable Shielding Guide per IEEE‐1143

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