PHASE CONVERTERS

A. General 455-1. Scope. This article covers the installation and use of phase converters. 455-2. Definition. A phase converter is an electrical device that converts single-phase power to 3-phase electrical power. Phase converters are of two types: static and rotary. (FPN): Phase converters have characteristics that modify the starting torque and locked-rotor current of motors served, and consideration is required in selecting a phase converter for a specific load. 455-3. Other Articles. All requirements of this Code shall apply to phase converters except as amended by this article. 455-4. Marking. Each phase converter shall be provided with a permanent nameplate indicating (1) manufacturer's name; (2) rated input and output voltages; (3) frequency; (4) rated single-phase input full-load amperes; (5) rated minimum and maximum single load in kVA or horsepower; and (6) maximum total load in kVA or horsepower. 455-5. Equipment Grounding Connection. A means for attachment of an equipment grounding conductor termination in accordance with Section 250-113 shall be provided. 455-6. Conductor Ampacity. The ampacity of the single-phase supply conductors shall not be less than 125 percent of the phase converter nameplate single-phase input full-load amperes. Exception: Where the phase converter supplies specific fixed loads, the conductors shall have an ampacity not less than 250 percent of the sum of the full-load, 3-phase current rating of the motors and other loads served where the input and output voltages of the phase converter are identical. Where the input and output voltages of the phase converter are different, the current as determined by this section shall be multiplied by the ratio of output to input voltage. (FPN): Single-phase conductors sized to prevent a voltage drop not exceding 3 percent from the source of supply to the phase converter will help ensure proper starting and operation of motor loads.