UL 347

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Medium-Voltage AC Contactors, Controllers, and Control Centers
UL 347
1.1 Scope and object

This standard is applicable to ac contactors applied at voltages in the range of 1 501V to 15kV, and metal-enclosed contactor-based controllers, control centers, and other control assemblies and associated equipment applied at voltages in the range of 751V to 15kV, designed for operation at frequencies of 50 or 60 Hz on three-phase systems. These requirements cover equipment intended for use in ordinary (non-hazardous) locations and installed in accordance with the applicable local installation codes and standards (see Annex a, Item 1). These requirements, as modified by the applicable national standards for fire pump controllers, also cover fire pump controllers (see Annex a, Item 2).This standard also includes requirements for controllers intended for service entrance applications. (See 5.204 and Annex a, Item 3.)This standard does not cover:

• a) equipment for use in classified (hazardous) locations as defined in the applicable installation codes or standards;
• b) components contained in contactors and contactor-based controllers for which individual component standards exist; and
• c) auxiliary low voltage control assemblies (see Annex a, Item 4).

This standard also includes requirements for reduced-voltage solid state controllers. It does not, however, cover equipment consisting solely of electronic or solid state devices, circuits, or systems, nor does it cover electronic variable speed motor controllers (power conversion equipment). This standard does not cover full-voltage controllers using only solid state devices in the main circuit.