New certification service and product category for power conversion equipment

This new certification service covers the evaluation of power conversion equipment (commonly referred to as motor drives) for compliance with UL 1604, The Standard for Safety of Electrical Equipment for Use in Class I and Class II, Division 2, and Class III Hazardous (Classified) Locations.

The equipment is evaluated to ensure there is no electrical/electronic circuitry capable, under normal operating conditions, of causing ignition of a specified gas-, vapor-, or dust-air mixture due to arcing or thermal means. This investigation can, in most cases, be coordinated with an ordinary locations (risk of fire and electrical shock) evaluation to UL 508C, Power Conversion Equipment.

The new category covers open or enclosed equipment that supplies power to control a motor or motors operating at a frequency or voltage different than the input supply voltage. This category also includes power-supply modules, input and output modules, SCR or transistor output modules, dynamic braking modules, and input/output accessory kits for power conversion equipment. This equipment is intended for use in Hazardous (Classified) Locations in accordance with Article 500 of the National Electrical Code.

The first US certification of a motor drive for use in a Division 2 area was issued by UL on April 12, 1999. Additional evaluations are underway.